Astronomy

Question about the relevant physical parameters to build a backyard observatory

Question about the relevant physical parameters to build a backyard observatory


We are searching data for your request:

Forums and discussions:
Manuals and reference books:
Data from registers:
Wait the end of the search in all databases.
Upon completion, a link will appear to access the found materials.

I live in a big city: São Paulo, Brazil. I would like to build a simple telescope dome to do some amateur sky obseravtions. But the whole project lies on the viability to see something interresting more than just some stars. Due to high luminosity of cities this is a good question to ask. So, which physical parameters are relevant to decide if a backyard observatory is a good holiday DIY project?


You've identified sky brightness as a potential concern for your observatory project. In that case, you should start by trying to measure it. Unihedron manufacturers sky quality meters that you can use to get scientific measurements in mag/arcsec2. This could give you a baseline for your considerations. You could roughly convert this measurement into a class on the Bortle scale. (But keep in mind that the conversion is approximate.) You could research whether the objects you might be interested in could be seen under that class of sky. More simply, you can use this site to see a map of light pollution in your area. Keep in mind that this map is generally accurate, but may be somewhat inaccurate at your specific location (as there are a huge number of factors that might affect sky brightness). You could, of course, buy a telescope and try to observe objects of interest with it. This would be the most direct way, obviously, to determine this project's feasibility in terms of what you're interested in observing.

I'm sure you realize that such an observatory should not be directly in the path of any artificial lights. It should be (obviously) on flat, sturdy land with an unobstructed view of the horizon. If you're asking specifically about building the dome itself, I have no experience with it. Someone else would have to add information form their experience.

I hope this helps.


Many astronomers are using electronic eyepieces to overcome light pollution. You may want to see what these devices can do in your area'

I use several of the Mallincam cameras in my observatory.

https://www.mallincam.net/

https://groups.io/g/MallinCam/topics

Some photos of my observatory and assistants

https://www.flickr.com/photos/[email protected]/sets/72157672437929982

More home observatory sites

http://obs.nineplanets.org/obs/obslist.html


Maragheh observatory

Maragheh observatory (Persian: رصدخانه مراغه ‎) was an astronomical observatory established in 1259 CE under the patronage of the Ilkhanid Hulagu and the directorship of Nasir al-Din al-Tusi, a Persian scientist and astronomer. Located in the heights west of Maragheh, which is today situated in the East Azerbaijan Province of Iran, it was once considered "the most advanced scientific institution in the Eurasian world". [1]

It was financed by waqf revenues, which allowed it to continue to operate even after the death of its founder, and was active for more than 50 years. It served as a model for later observatories including the 15th-century Ulugh Beg Observatory in Samarkand, the 16th-century Taqi al-Din observatory in Constantinople, and the 18th-century Jai Singh observatory in Jaipur. [2]


Ulugh Beg: The Rising Astronomer

Ulugh Beg was interested in astronomy from an early age, and when he became sultan he continued to be far more interested in the arts, culture and scholarly pursuits than in governing an empire. In fact, Ulugh Beg is best remembered as an astronomer and mathematician. Otherwise, his name would have likely been relegated to a mere footnote in the history books.

Ulugh Beg was born in 1394 in Sultaniyah, northwestern Iran. He was the eldest son of Shah Rukh, and a grandson of Timur (known also as Tamerlane), the founder of the Timurid Empire. Ulugh Beg was born during his grandfather’s Persian campaign, and was given the name Muhammad Taraghay ibn Shahrukh ibn Timur. Incidentally, “Ulugh Beg” may be roughly translated as “Great Ruler”. This was the Timurid sultan’s nickname, rather than personal name.

As a child, Ulugh Beg accompanied his grandfather on his various military campaigns, giving him the chance to travel widely. In 1398, for instance, Timur was on a campaign in northern India, capturing the city of Delhi, whilst in 1402, he was in Anatolia, defeating the Ottoman sultan, Bayezid I, at the Battle of Ankara .

Since his childhood, Ulugh Beg took a greater interest in the arts and culture, rather than in wars and conquests. He was particularly passionate about astronomy, an interest which may have originated from a visit to the ruins of the Maragheh Observatory. This observatory, which dates to the 13th century, is located in northwestern Iran, not too far from Ulugh Beg’s birthplace. The Maragheh Observatory was built under the patronage of Hulagu Khan, the founder of the Ilkhanate, and a grandson of Genghis Khan . The head astronomer of the observatory was the Persian polymath Nasir al-Din Tusi.

The Maragheh Observatory fell into disuse by the beginning of the 14 th century as a result of its loss of patronage. It did however maintain its fame for centuries to come, and the fact that its plan and arrangement of instruments influenced the design of future observatories, such as the Ulugh Beg Observatory, is testament to its legacy.

Painting of Al-Tusi and his colleagues working on the Zij-i Ilkhani at the Maragheh observatory. ( Public domain )


Sanctuary: An Astronomer's Home Observatory

The dollars and cents that go into moving vary greatly depending on a number of factors.

Zillow Tools

For hobbyist Jonathan Fay, a trip to the stars awaits any time he wants to go.

Jonathan Fay lives a double life. By day, he works in software engineering, but once the sun goes down, he opens a window to the heavens — right in his own backyard.

The amateur astronomer designed and built an observatory behind his Woodinville, Washington, home to house his 12-inch telescope. There, he gazes at planetary nebula and photographs galaxies. For Fay, having his own sanctuary is out of this world.

How would you describe your sanctuary?
My observatory is a place of peace where I can collect my gear and spend time with the universe. The nature of astronomy in the Pacific Northwest is challenging, but I’m able to open the dome and start observing without having to set up ahead of time and rush to cover things up when it rains.

What do you like best about the physical space?
It’s separate from the activity of my home, and it’s quiet. I don’t disturb anyone else, and they don’t disturb me.

What’s your home like? Is your sanctuary an extension or departure from your home?
Our home is a two-story wood and brick home. The observatory blends nicely with the house and barn in style, but the dome clearly sets it apart.

Did you have your sanctuary in mind when you chose your home?
No. A few years after I moved in, I realized I needed a more permanent place than a second-floor porch off the bedroom to set up my new telescope.

What was the tipping point that made you decide to create a sanctuary?
When I would do astrophotography imaging runs on the second-floor porch, people would turn on lights or walk around, and the light and vibration would ruin the image. My wife didn’t like having to shut down her life for my hobby.

How did you build your sanctuary?
I designed and built the observatory. I had some occasional help from friends when I needed lifting or a second pair of hands. I also had help from my kids handing me screws and nails while I worked.

What was the biggest challenge in creating your sanctuary?
Round stuff is hard. Especially when it has to rotate and be level. The dome was a hemisphere, so it was round in more than two dimensions. Woodworking tools are not optimized for round things.

Has your sanctuary always looked the same, or has it changed over time?
We recently added wood floors from carpet. And we put on a new roof when we re-roofed the rest of the buildings on the property.

How much time do you typically spend in your sanctuary?
Sometimes many hours for several days in a row. Sometimes I go weeks without going inside. It depends on the ebb and flow of life — and how bad I need it.

How did you get into astronomy in the first place?
My aunt gave me a telescope when I was about 12. Since then I have loved space and astronomy, but when I could put a computer-controlled camera on a telescope, that made me want my own Hubble in my backyard.

Does your hobby influence what you do professionally or vice versa?
Building my observatory, writing all the software for it, and doing astronomical imaging helped me create the WorldWide Telescope project with two of my co-workers. Now millions of people can visit space on their computer or planetarium because of it.

Do you share your sanctuary with anyone? What about your home?
I will share the observatory with just about anyone who asks, and sometimes I invite people to join me. I share my home with my wife and five active kids. So sometimes a getaway is in order!

If you had a do-over, would you change anything about your sanctuary?
While I love the look of the dome, I would make the shutters open wider to accommodate a bigger telescope.

Do you wish you had found your sanctuary sooner?
It came at the right time for me, and I returned to update it when that time was right.

What advice would you share with those who dream of having a sanctuary someday?
You’re not getting any younger. Just go for it, even if you don’t use it as much as you think you need to to justify the cost. It will always be a great story to share.


By Mike Simmons

A few primitive mountaintop cabins set among tall pine trees, hikers exploring the rugged wilderness on foot and horseback, a commanding view of the orchards or a pioneer community in the valley a mile below — this was the unlikely setting for a revolution in the making, a revolution in science that could alter our understanding of the sun and stars and our place among them. Many fundamental questions would be answered as Mount Wilson developed into the center of the astronomical world in the first decades of the twentieth century. Imagination, innovation, and a rare collection of scientific genius would become hallmarks of the Mount Wilson Observatory, a tradition established at the very beginning by its founder.George Ellery Hale was born into a wealthy Chicago family on June 29, 1868. In the post-Civil War period the study of astronomy consisted mostly of the measurement of star positions, brightness and motions. The days of the spectroscopic study of the sun and stars’ composition, and the consequent need for very large telescopes, lay far in the future. the world’s largest telescope (excluding the relatively poor quality speculum metal reflectors, such as Lord Rosse’s “Levithan of Parsontown”) was the 18 1/2-inch Clark reflector of Chicago’s Dearborn Observatory.

Four years before Hale’s birth, in 1864, Benjamin Wilson had built a trail to the top of a broad mountain, later known as Wilson’s Peak, in Southern California’s Sierra Madre range. The lumber he sought for use on his ranch in the valley below did not prove suitable, and the trail lay abandoned. The town of Pasadena at the base of the mountain range would not be established for another five years, and the broad expanses of the San Gabriel Valley were broken only by the fences of the great ranchos.

In 1873, a group of families from Indiana started a new community at the base of the mountains on part of Benjamin Wilson’s old ranch. The “Indiana Colony” quickly grew into the thriving community of Pasadena, and within ten years land values had increased tenfold.

Aside from the occasional explorer or prospector, the mountains above Pasadena attracted little attention. When John Muir climbed to a point near Wilson’s Peak in 1877, he described the range as “more rigidly inaccessible than any other I ever attempted to penetrate.”

Wilson’s old trail was soon refurbished, however, and in the 1880’s the adventuresome of Pasadena commonly made the difficult 9-mile journey. Wilson’s old half-way house served as overnight accommodations, the one-way trip taking two days on horseback.

Meanwhile, George Hale had grown into an extremely industrious and precocious teenager. Having become quite proficient with tools his father had supplied, he built his first telescope in the backyard “laboratory” he had constructed himself. In later life, Hale would build the world’s largest telescope four times, but his first telescope failed to perform well, and soon he bought expert advice. Having noticed a small box-like structure in a neighbor’s yard, he was told, “A queer man lives nights in that cheese box and tells fortunes by the stars.” The “queer man” turned out to be the great double star observer S.W. Burnham, who was still working as a court reporter during the day and making his observations as an amateur each night. Burnham told him of a used 4-inch Clark refractor that was available, and his father, recognizing the remarkable talents of the fourteen-year-old, purchased the instrument, starting him on a course of study that would last him his entire life.

Hale spent four years studying at the Massachusetts Institute of Technology, but, although he did well, he found formal course work less interesting than research. Working at Harvard College Observatory as a volunteer assistant, Hale first tested the spectroheliograph, an important instrument he had invented which would later become a valuable tool on the powerful solar telescope at Mount Wilson. After graduation, Hale’s father once again helped finance his son’s dreams by buying a 12-inch refractor with a Brashear lens and Warner and Swasey mount. This was a suitable instrument to carry the new spectrograph, and Hale now began publishing the results of original research conducted in the new Kenwood Observatory, also provided by his father, located next to the family home. He hired an assistant, Ferdinand Ellerman, who would later become the first astronomer to join Hale at the new observatory at Mount Wilson.

Potential Observatory Site
While Hale was a student, Mount Wilson began to attract attention as a potential observatory site when E.F. Spence, a banker and former mayor of Los Angeles, promised the University of Southern California $50,000 toward the construction of a 40-inch refracting telescope, which would be the world’s largest. President Bovard of USC sought advice from Edward Pickering, director of Harvard College Observatory, and suggested that Mount Wilson be considered for a Harvard Observatory station, which would share the mountain with the proposed Spence Observatory. A Harvard expedition led by William Pickering, the director’s brother, and including Alvan Clark, the great optician, tested the observing conditions on Mount Wilson in January 1889. Pickering said of Mount Wilson, “I consider this the point of all others to place the largest and finest telescope in the world.” By spring, Harvard had installed a Clark 13-inch refractor on the mountaintop. Meanwhile, Bovard, on behalf of USC, ordered the 40-inch telescope from Alvan Clark and Sons.

The Harvard Observatory station on Mount Wilson. The cylindrical metal turret housing the telescope attracted much unwanted attention from nearby campers. Photo: Carnegie/ Huntington Library

The hardships suffered by the Harvard astronomers on Mount Wilson were enormous. The winter of 1889-90 was one of the severest on record, with frequent rain and snow ruining delicate instruments. Difficulties developed with the owner of the land leased for the observatory, and the observers were so isolated they complained of being “practically excluded from the world.” Visitors to the mountaintop were no help, as observer Robert Black explained in a letter to Pickering describing encounters with tourists from nearby camps: “This morning a party of them came around the building when we were asleep — tried to pry open the door and windows — climbed the dome and hammered the tin, and climaxed the whole affair by moving the slides of the recorder down and piling them on top of each other.”

These difficulties, combined with misunderstandings with USC, led Pickering to abandon the site after just 18 months. The worsening condition of the Southern California economy caused support for the proposed Spence Observatory’s 40-inch telescope to all but disappear. Thus the mountain was abandoned to the hikers, although local interest in astronomy did not disappear on nearby Echo Mountain an observatory with a 16-inch refractor was built by Professor Thaddeus Lowe in 1894 and remained in operation for 34 years.

New Home for 40-inch
The glass for the 40-inch lens had been ordered by Alvan Clark and Sons before the plans for the telescope dissolved. Hearing that the glass was available, Hale approached President Harper of the University of Chicago with plans of his own. Together they convinced Chicago streetcar magnate Charles Yerkes to donate sufficient funds to complete the telescope and to construct a building for it on Lake Geneva, Wisconsin, near Chicago. The Mount Wilson Toll Road Company wrote to Hale suggesting that the 40-inch be placed on Mount Wilson, as originally planned. Hale replied, perhaps regretfully, that Mount Wilson was “too far away.” Remaining in Wisconsin, the 40-inch was completed in 1897.

Hale’s first telescope that was the largest in the world, the Yerkes 40-inch refractor. To this day, it is the largest telescope ever made using a lens to focus light. Photo: University of Chicago/ Yerkes Observatory

As the Yerkes Observatory’s first director, Hale collected a strong staff, the nucleus of the future Mount Wilson Observatory staff, including Ellerman, Walter Adams and George Ritchey. Adams would later succeed Hale as the director of Mount Wilson Observatory, and Ritchey, who first learned optics at Yerkes, would become famous as the maker of the Mount Wilson 60-inch and 100-inch mirrors.

In 1902, Hale learned that Andrew Carnegie had established the Carnegie Institution of Washington to support original research in all scientific fields. He immediately saw the possibilities for furthering his own lines of research, having determined that new methods were necessary in order to advance our understanding of the sun and stars. Hale felt new telescopes should be designed to suit the problems they are meant to investigate rather than the other way around. Telescopes such as the Lick 36-inch and Yerkes 40-inch refractors, great as they might be for many purposes, were not well-suited to the study of the solar spectrum. The coelostat (in which the majority of the telescope remains stationary and a single mirror tracks the sun) had obvious advantages for the study of the sun. With such an instrument, one could use much larger and more powerful spectroscopes than could be carried by even the largest moving telescopes.

Large Reflectors Needed
Hale also felt the future of stellar spectroscopy would best be served by large reflectors. Refractors had reached their practical size limit with the 40-inch, but more light was needed if the stars’ spectra were to be examined in the same detail as the sun’s. In 1896, Hale’s father had yet made another contribution to his son’s career making him a gift of a 60-inch optical glass disc for the mirror of a giant reflecting telescope. Had Hale’s father not died soon after, he might have provided funds for the mounting, but as it was, the disc lay in the Yerkes Observatory basement while Hale searched vainly for a donor to complete the telescope. He even wrote to Col. Griffith in Los Angeles, who later gave Griffith Park to that city.

Chief among Hale’s plans for the future was the furtherance of the “New Astronomy”, the combination of physics and astronomy which he termed “astrophysics.” Astronomy was still primarily involved with describing a star’s brightness and motion rather than what it was made of. Hale felt that a physical laboratory as part of an observatory would yield information on spectra that would be invaluable in the study of the physical properties of the sun and stars.

Hale was asked to serve on the Advisory Committee on Astronomy of the new Carnegie Institution, joining Edward Pickering, Simon Newcomb, Samuel Langley, and Lewis Boss. This seemed an opportunity to further his views as to how the Carnegie money should be spent, but Hale stood alone on this committee as a staunch proponent of astrophysics, and he had found difficulty in gaining support for some of this ideas. At first the institution made only small grants, but soon a committee was formed to study the establishment of a southern and a solar observatory. W.J. Hussey of the Lick Observatory was sent to investigate several sites in the Southwest United States, including Flagstaff, Mount Palomar and Mount Lowe, but Mount Wilson received the highest recommendation.

Hale decided to visit Mount Wilson himself and, with W.W. Campbell, Director of Lick Observatory, he journeyed up the mountain on June 25, 1903. Low clouds and fog covered Pasadena that morning as Hale, depressed by the gloomy skies and doubting if “Wilson’s Peak” would provide for a satisfactory site for a solar observatory, started up the trail. All of his misgivings were replaced with delight, however, when halfway up the mountain he burst out into blue sky and brilliant sunshine. Hussey had preceded them, setting up a nine-inch refractor, and with this telescope Hale made his first solar observations from the mountaintop. Ecstatic over the excellent conditions, Hale decided he must build his observatory there. Already he saw, as Harold Babcock later described in his poem, “In 1903”

A picture growing clear before his eyes
Of all that was to be in years to come
Upon that mountaintop

Soon after his return to Chicago, Hale applied to the Carnegie Institution for a great solar observatory. Not waiting for a response, he moved his family to Pasadena in December, partially because of his daughter’s worsening asthma in the harsh Wisconsin climate. Hale returned to Pasadena on December 20, 1903, one year to the day the Mount Wilson Solar Observatory would become reality, and five years to the day before the first photographs would be taken with the completed 60-inch mirror.

A limited expedition from Yerkes Observatory to Mount Wilson was mounted, funded by Yerkes and several local California philanthropists. One of these was John Hooker, a founder of the California Academy of Science. For Hale, this was the beginning of a long relationship with Hooker, culminating in Hooker’s donations of the funds for the mirror of the 100-inch telescope, named in his honor. A 15-inch coelostat with a 6-inch objective lens, originally used for eclipse observations, was brought to Mount Wilson for trials in March, 1904. Ferdinand Ellerman followed within weeks, and Adams and Ritchey migrated west two months later. When Francis Pease, who would become the chief designer of every major telescope on Mount Wilson, also left Yerkes for the West, Hale had brought almost all of the Yerkes staff to California, keeping intact the nucleus of a group that would soon make scientific history.

Mountaintop Conditions
Conditions on the mountain were still very primitive, a situation in which Ellerman reveled. Adams later described his first sight of Ellerman on his way up the mountain: “He wore a ‘ten-gallon hat’, high mountain boots, and a full cartridge belt from which hung a revolver on one side and a hunting knife on the other. I was greatly impressed and pictured a struggle for existence on the wild mountain top, which bore little resemblance to later actuality.” The mountain could be reached only by a strenuous hike or by renting a burro. Adams wrote: “Books could be written about the personal character of these sagacious beasts… One would deliberately expand his chest when the saddle was placed upon him so that the rider, after a good start, would presently find the saddle rolling beneath him at some awkward point in the trail…” Hale had the misfortune of packing a valuable diffraction grating on the back of a burro who had a tendency to lie down and roll over on the trail. Still the animals made 60 trips transporting the parts of the Snow telescope up the hill without mishap.

Confident that the Carnegie Institution would fund the Solar Observatory, on June 13, 1904, Hale signed a 99-year lease with the Mount Wilson Toll Road Company for 40 acres on the mountaintop. The land owners provided the property rent-free, anticipating the world-wide fame the Observatory would bring to Mount Wilson and the increased tourist business that would mean. Hale was to make good use of the land that summer. With a $10,000 grant from the Carnegie Institution, the Snow solar telescope was brought from Yerkes, soon to become the world’s first permanently mounted solar telescope. The massive stone piers were built before the year was out, including the 27-foot high south pier. The “monestary” (the astronomers’ living quarters) was built, a powerhouse with gasoline-driven electric generator was constructed, and a water pump, reservoir and pipe lines were installed. With the new observatory already attracting a great deal of attention, many famous scientists were visiting even before observations were begun. By the time the Carnegie Board of Trustees met in December, Hale had already spent $27,000 of his own money financing his dream. Some thought him a reckless gambler, but others saw him as a genius and visionary who simply could not accept the possibility of failure.

It was at Martin’s camp on the Mount Wilson trail, on December 20, 1904, that Hale received the news that the Carnegie Board had approved his plans for the Mount Wilson Solar Observatory (the word “Solar” was dropped with the completion of the 100-inch telescope in 1917). What the future held, only Hale could have imagined. Already, even before the Snow telescope was completed, he had discussed with Adams plans for the next solar telescope, one with a “high tower and no tube” and in his typical straightforward manner, climbed a tree with a telescope to test the seeing conditions such a telescope would enjoy. Already he was making plans for bringing the 60-inch disk from Yerkes to build the world’s greatest telescope. Before that one was done he would be performing an even larger one. One great step forward would have been enough to assure a place in history for Hale and the Observatory he founded, but he planned one scientific revolution after another on Mount Wilson. Four years after the Observatory was begun, four great telescopes, including the world’s largest solar and stellar instruments, would reside there. Many fundamental problems in astronomy — the nature of sunspots, the temperature and composition of the stars, even the structure of the universe — would gradually be addressed. Many of the world’s greatest astronomers and physicists would make the pilgrimage to Mount Wilson to add to the contributions of the first small, select group working there, about whom Babcock wrote:

How fortunate that little group of men
Whom in those next swift years he chose to be
His friends and colleagues in the appointed task
Of realizing what he had foreseen!

The author, Mike Simmons is a long-time Mount Wilson enthusiast and supporter and more recently a founder and president of Astronomers Without Borders.


Contents

Ahmad Dallal notes that, unlike the Babylonians, Greeks, and Indians, who had developed elaborate systems of mathematical astronomical study, the pre-Islamic Arabs relied entirely on empirical observations. These observations were based on the rising and setting of particular stars, and this area of astronomical study was known as anwa. Anwa continued to be developed after Islamization by the Arabs, where Islamic astronomers added mathematical methods to their empirical observations. [11]

Scripture Edit

While Abbasid era and later Muslim scholars made great contributions to astronomy, [12] early scripture of the tafsir (or exegesis) of the Quran, and hadith (records of sayings and doings of the Prophet Muhammad) indicate early Muslims concepts of the universe were based on the appearance and movement of sun, moon, stars, and planets in the sky. [13] [a] and not the ideas of some Greek philosophers of the earth being spherical, the sun much larger than the earth and much more distant than the moon, etc. [16] The Quran frequently mentions the "Earth" or "land" as "spreadout", a "bed", "carpet" [b] the heavens being a canopy or building (Q.2:22 binaa ( بِنَاء ) or binaan).

In Tafsir al-Jalalayn, Quranic scholar Jalāl al-Dīn al-Maḥallī (1389–1460 CE) writes about how scholars of Islamic law interpret verse Q.88:20 (which reads: "And the earth how it was laid out flat?" Wa-ila al-ardi kayfa sutihat, وَإِلَى ٱلۡأَرۡضِ كَیۡفَ سُطِحَتۡ):

"And the earth how it was laid out flat?" and thus infer from this the power of God exalted be He and His Oneness? The commencing with the mention of camels is because they are closer in contact with it the earth than any other animal. As for His words sutihat ‘laid out flat’ this on a literal reading suggests that the earth is flat which is the opinion of the scholars of the revealed Law ["وعليه علماء الشرع"] and not a sphere as astronomers [ahl al-hay’a, أهْل الهَيْئَة ] have it, even if this latter does not contradict any of the pillars of Islamic Law [الشَّرْع ]. [17]

Other scriptural references are also not consistent with a spherical earth. The literal meaning of Quranic verse Q.18:86: Till, when he reached the setting-place of the sun, he found it setting in a muddy spring, . ", is confirmed by Tafsir al-Tabari 18:86, where interpretations disagrees only on whether the verse means that the sun sets in a muddy (hami'ah) spring or a hot (hamiyah) spring. [c] Tafsir al-Tabari for verse 2:22 includes a couple of narrations transmitted by a chain going back to early Muslims saying ". and the sky a canopy. ", which al-Tabari (839–923 CE) interpreted to mean "The canopy of the sky over the earth is in the form of a dome, and it is a roof over the earth." [19] A sahih hadith from Sunan Abu Dawood (Hadith 4002) also talks of Muhammad telling companion Abu Dharr al-Ghifari, "Do you know where this sets? . It sets in a spring of warm water (Hamiyah)." [20]

ʿAbbāsīyah era Edit

Following the Islamic conquests, under the early caliphate, Muslim scholars began to absorb Hellenistic and Indian astronomical knowledge via translations into Arabic (in some cases via Persian).

The first astronomical texts that were translated into Arabic were of Indian [21] and Persian origin. [22] The most notable of the texts was Zij al-Sindhind, [d] an 8th-century Indian astronomical work that was translated by Muhammad ibn Ibrahim al-Fazari and Yaqub ibn Tariq after 770 CE with the assistance of Indian astronomers who visited the court of caliph Al-Mansur in 770. [21] Another text translated was the Zij al-Shah, a collection of astronomical tables (based on Indian parameters) compiled in Sasanid Persia over two centuries. Fragments of texts during this period indicate that Arabs adopted the sine function (inherited from India) in place of the chords of arc used in Greek trigonometry. [11]

According to David King, after the rise of Islam, the religious obligation to determine the qibla and prayer times inspired progress in astronomy. [23] Early Islam's history shows evidence of a productive relationship between faith and science. Specifically, Islamic scientists took an early interest in astronomy, as the concept of keeping time accurately was important for the five daily prayers central to the faith. Early Islamicate scientists constructed astronomical tables specifically to determine the exact times of prayer for specific locations around the continent, serving effectively as an early system of time zones. [24]

The House of Wisdom was an academy established in Baghdad under Abbasid caliph Al-Ma'mun in the early 9th century. Astronomical research was greatly supported by the Abbasid caliph al-Mamun through the House of Wisdom. Baghdad and Damascus became the centers of such activity.

The first major Muslim work of astronomy was Zij al-Sindhind by Persian mathematician al-Khwarizmi in 830. The work contains tables for the movements of the Sun, the Moon and the five planets known at the time. The work is significant as it introduced Ptolemaic concepts into Islamic sciences. This work also marks the turning point in Islamic astronomy. Hitherto, Muslim astronomers had adopted a primarily research approach to the field, translating works of others and learning already discovered knowledge. Al-Khwarizmi's work marked the beginning of nontraditional methods of study and calculations. [25]

Doubts on Ptolemy Edit

In 850, al-Farghani wrote Kitab fi Jawami (meaning "A compendium of the science of stars"). The book primarily gave a summary of Ptolemic cosmography. However, it also corrected Ptolemy based on findings of earlier Arab astronomers. Al-Farghani gave revised values for the obliquity of the ecliptic, the precessional movement of the apogees of the Sun and the Moon, and the circumference of the Earth. The book was widely circulated through the Muslim world, and translated into Latin. [26]

By the 10th century texts appeared regularly whose subject matter was doubts concerning Ptolemy (shukūk). [27] Several Muslim scholars questioned the Earth's apparent immobility [28] [29] and centrality within the universe. [30] From this time, independent investigation into the Ptolemaic system became possible. According to Dallal (2010), the use of parameters, sources and calculation methods from different scientific traditions made the Ptolemaic tradition "receptive right from the beginning to the possibility of observational refinement and mathematical restructuring". [31]

Egyptian astronomer Ibn Yunus found fault in Ptolemy's calculations about the planet's movements and their peculiarity in the late 10th century. Ptolemy calculated that Earth's wobble, otherwise known as precession, varied 1 degree every 100 years. Ibn Yunus contradicted this finding by calculating that it was instead 1 degree every 70 1 ⁄ 4 years.

Between 1025 and 1028, Ibn al-Haytham wrote his Al-Shukuk ala Batlamyus (meaning "Doubts on Ptolemy"). While maintaining the physical reality of the geocentric model, he criticized elements of the Ptolemic models. Many astronomers took up the challenge posed in this work, namely to develop alternate models that resolved these difficulties. In 1070, Abu Ubayd al-Juzjani published the Tarik al-Aflak where he discussed the "equant" problem of the Ptolemic model and proposed a solution. [ citation needed ] In Al-Andalus, the anonymous work al-Istidrak ala Batlamyus (meaning "Recapitulation regarding Ptolemy"), included a list of objections to the Ptolemic astronomy.

Nasir al-Din al-Tusi, the creator of the Tusi Couple, also worked heavily to expose the problems present in Ptolemy's work. In 1261, Tusi published his Tadkhira, which contained 16 fundamental problems he found with Ptolemaic astronomy, [32] and by doing this, set off a chain of Islamic scholars that would attempt to solve these problems. Scholars such as Qutb al-Din al-Shirazi, Ibn al-Shatir, and Shams al-Din al-Khafri all worked to produce new models for solving Tusi's 16 Problems, [33] and the models they worked to create would become widely adopted by astronomers for use in their own works.

Earth rotation Edit

Abu Rayhan Biruni (b. 973) discussed the possibility of whether the Earth rotated about its own axis and around the Sun, but in his Masudic Canon, he set forth the principles that the Earth is at the center of the universe and that it has no motion of its own. [34] He was aware that if the Earth rotated on its axis, this would be consistent with his astronomical parameters, [35] but he considered this a problem of natural philosophy rather than mathematics. [36] [4]

His contemporary, Abu Sa'id al-Sijzi, accepted that the Earth rotates around its axis. [37] Al-Biruni described an astrolabe invented by Sijzi based on the idea that the earth rotates:

I have seen the astrolabe called Zuraqi invented by Abu Sa'id Sijzi. I liked it very much and praised him a great deal, as it is based on the idea entertained by some to the effect that the motion we see is due to the Earth's movement and not to that of the sky. By my life, it is a problem difficult of solution and refutation. [. ] For it is the same whether you take it that the Earth is in motion or the sky. For, in both cases, it does not affect the Astronomical Science. It is just for the physicist to see if it is possible to refute it. [38]

The fact that some people did believe that the earth is moving on its own axis is further confirmed by an Arabic reference work from the 13th century which states:

According to the geometers [or engineers] (muhandisīn), the earth is in constant circular motion, and what appears to be the motion of the heavens is actually due to the motion of the earth and not the stars. [36]

At the Maragha and Samarkand observatories, the Earth's rotation was discussed by al-Kātibī (d. 1277), [39] Tusi (b. 1201) and Qushji (b. 1403). The arguments and evidence used by Tusi and Qushji resemble those used by Copernicus to support the Earth's motion. [28] [29] However, it remains a fact that the Maragha school never made the big leap to heliocentrism. [40]

Alternative geocentric systems Edit

In the 12th century, non-heliocentric alternatives to the Ptolemaic system were developed by some Islamic astronomers in al-Andalus, following a tradition established by Ibn Bajjah, Ibn Tufail, and Ibn Rushd.

A notable example is Nur ad-Din al-Bitruji, who considered the Ptolemaic model mathematical, and not physical. [41] [42] Al-Bitruji proposed a theory on planetary motion in which he wished to avoid both epicycles and eccentrics. [43] He was unsuccessful in replacing Ptolemy's planetary model, as the numerical predictions of the planetary positions in his configuration were less accurate than those of the Ptolemaic model. [44] One original aspects of al-Bitruji's system is his proposal of a physical cause of celestial motions. He contradicts the Aristotelian idea that there is a specific kind of dynamics for each world, applying instead the same dynamics to the sublunar and the celestial worlds. [45]

In the late thirteenth century, Nasir al-Din al-Tusi created the Tusi couple, as pictured above. Other notable astronomers from the later medieval period include Mu'ayyad al-Din al-'Urdi (c. 1266), Qutb al-Din al Shirazi (c. 1311), Sadr al-Sharia al-Bukhari (c. 1347), Ibn al-Shatir (c. 1375), and Ali al-Qushji (c. 1474). [46]

In the fifteenth century, the Timurid ruler Ulugh Beg of Samarkand established his court as a center of patronage for astronomy. He studied it in his youth, and in 1420 ordered the construction of Ulugh Beg Observatory, which produced a new set of astronomical tables, as well as contributing to other scientific and mathematical advances. [47]

Several major astronomical works were produced in the early 16th century, including ones by 'Abd al-Ali al-Birjandi (d. 1525 or 1526) and Shams al-Din al-Khafri (fl. 1525). However, the vast majority of works written in this and later periods in the history of Islamic sciences are yet to be studied. [29]

Europe Edit

Several works of Islamic astronomy were translated to Latin starting from the 12th century.

The work of al-Battani (d. 929), Kitāb az-Zīj ("Book of Astronomical Tables"), was frequently cited by European astronomers and received several reprints, including one with annotations by Regiomontanus. [48] Copernicus, in his book that initiated the Copernican Revolution, the De Revolutionibus Orbium Coelestium, mentioned al-Battani no fewer than 23 times, [49] and also mentions him in the Commentariolus. [50] Tycho Brahe, Riccioli, Kepler, Galileo and others frequently cited him or his observations. [51] His data is still used in geophysics. [52]

Around 1190, Al-Bitruji published an alternative geocentric system to Ptolemy's model. His system spread through most of Europe during the 13th century, with debates and refutations of his ideas continued to the 16th century. [53] In 1217, Michael Scot finished a Latin translation of al-Bitruji's Book of Cosmology (Kitāb al-Hayʾah), which became a valid alternative to Ptolemy's Almagest in scholastic circles. [45] Several European writers, including Albertus Magnus and Roger Bacon, explained it in detail and compared it with Ptolemy's. [53] Copernicus cited his system in the De revolutionibus while discussing theories of the order of the inferior planets. [53] [45]

Some historians maintain that the thought of the Maragheh observatory, in particular the mathematical devices known as the Urdi lemma and the Tusi couple, influenced Renaissance-era European astronomy and thus Copernicus. [4] [54] [55] [56] [57] Copernicus used such devices in the same planetary models as found in Arabic sources. [58] Furthermore, the exact replacement of the equant by two epicycles used by Copernicus in the Commentariolus was found in an earlier work by Ibn al-Shatir (d. c. 1375) of Damascus. [59] Copernicus' lunar and Mercury models are also identical to Ibn al-Shatir's. [60]

While the influence of the criticism of Ptolemy by Averroes on Renaissance thought is clear and explicit, the claim of direct influence of the Maragha school, postulated by Otto E. Neugebauer in 1957, remains an open question. [40] [61] [62] Since the Tusi couple was used by Copernicus in his reformulation of mathematical astronomy, there is a growing consensus that he became aware of this idea in some way. It has been suggested [63] [64] that the idea of the Tusi couple may have arrived in Europe leaving few manuscript traces, since it could have occurred without the translation of any Arabic text into Latin. One possible route of transmission may have been through Byzantine science, which translated some of al-Tusi's works from Arabic into Byzantine Greek. Several Byzantine Greek manuscripts containing the Tusi-couple are still extant in Italy. [65] Other scholars have argued that Copernicus could well have developed these ideas independently of the late Islamic tradition. [66] Copernicus explicitly references several astronomers of the "Islamic Golden Age" (10th to 12th centuries) in De Revolutionibus: Albategnius (Al-Battani), Averroes (Ibn Rushd), Thebit (Thabit Ibn Qurra), Arzachel (Al-Zarqali), and Alpetragius (Al-Bitruji), but he does not show awareness of the existence of any of the later astronomers of the Maragha school. [50]

It has been argued that Copernicus could have independently discovered the Tusi couple or took the idea from Proclus's Commentary on the First Book of Euclid, [67] which Copernicus cited. [68] Another possible source for Copernicus's knowledge of this mathematical device is the Questiones de Spera of Nicole Oresme, who described how a reciprocating linear motion of a celestial body could be produced by a combination of circular motions similar to those proposed by al-Tusi. [69]

China Edit

Islamic influence on Chinese astronomy was first recorded during the Song dynasty when a Hui Muslim astronomer named Ma Yize introduced the concept of seven days in a week and made other contributions. [70]

Islamic astronomers were brought to China in order to work on calendar making and astronomy during the Mongol Empire and the succeeding Yuan Dynasty. [71] [72] The Chinese scholar Yeh-lu Chu'tsai accompanied Genghis Khan to Persia in 1210 and studied their calendar for use in the Mongol Empire. [72] Kublai Khan brought Iranians to Beijing to construct an observatory and an institution for astronomical studies. [71]

Several Chinese astronomers worked at the Maragheh observatory, founded by Nasir al-Din al-Tusi in 1259 under the patronage of Hulagu Khan in Persia. [73] One of these Chinese astronomers was Fu Mengchi, or Fu Mezhai. [74] In 1267, the Persian astronomer Jamal ad-Din, who previously worked at Maragha observatory, presented Kublai Khan with seven Persian astronomical instruments, including a terrestrial globe and an armillary sphere, [75] as well as an astronomical almanac, which was later known in China as the Wannian Li ("Ten Thousand Year Calendar" or "Eternal Calendar"). He was known as "Zhamaluding" in China, where, in 1271, [74] he was appointed by Khan as the first director of the Islamic observatory in Beijing, [73] known as the Islamic Astronomical Bureau, which operated alongside the Chinese Astronomical Bureau for four centuries. Islamic astronomy gained a good reputation in China for its theory of planetary latitudes, which did not exist in Chinese astronomy at the time, and for its accurate prediction of eclipses. [5]

Some of the astronomical instruments constructed by the famous Chinese astronomer Guo Shoujing shortly afterwards resemble the style of instrumentation built at Maragheh. [73] In particular, the "simplified instrument" (jianyi) and the large gnomon at the Gaocheng Astronomical Observatory show traces of Islamic influence. [5] While formulating the Shoushili calendar in 1281, Shoujing's work in spherical trigonometry may have also been partially influenced by Islamic mathematics, which was largely accepted at Kublai's court. [76] These possible influences include a pseudo-geometrical method for converting between equatorial and ecliptic coordinates, the systematic use of decimals in the underlying parameters, and the application of cubic interpolation in the calculation of the irregularity in the planetary motions. [5]

Hongwu Emperor (r. 1368-1398) of the Ming Dynasty (1328–1398), in the first year of his reign (1368), conscripted Han and non-Han astrology specialists from the astronomical institutions in Beijing of the former Mongolian Yuan to Nanjing to become officials of the newly established national observatory.

That year, the Ming government summoned for the first time the astronomical officials to come south from the upper capital of Yuan. There were fourteen of them. In order to enhance accuracy in methods of observation and computation, Hongwu Emperor reinforced the adoption of parallel calendar systems, the Han and the Hui. In the following years, the Ming Court appointed several Hui astrologers to hold high positions in the Imperial Observatory. They wrote many books on Islamic astronomy and also manufactured astronomical equipment based on the Islamic system.

The translation of two important works into Chinese was completed in 1383: Zij (1366) and al-Madkhal fi Sina'at Ahkam al-Nujum, Introduction to Astrology (1004).

In 1384, a Chinese astrolabe was made for observing stars based on the instructions for making multi-purposed Islamic equipment. In 1385, the apparatus was installed on a hill in northern Nanjing.

Around 1384, during the Ming Dynasty, Hongwu Emperor ordered the Chinese translation and compilation of Islamic astronomical tables, a task that was carried out by the scholars Mashayihei, a Muslim astronomer, and Wu Bozong, a Chinese scholar-official. These tables came to be known as the Huihui Lifa (Muslim System of Calendrical Astronomy), which was published in China a number of times until the early 18th century, [77] though the Qing Dynasty had officially abandoned the tradition of Chinese-Islamic astronomy in 1659. [78] The Muslim astronomer Yang Guangxian was known for his attacks on the Jesuit's astronomical sciences.

Korea Edit

In the early Joseon period, the Islamic calendar served as a basis for calendar reform being more accurate than the existing Chinese-based calendars. [79] A Korean translation of the Huihui Lifa, a text combining Chinese astronomy with Islamic astronomy works of Jamal ad-Din, was studied in Korea under the Joseon Dynasty during the time of Sejong in the fifteenth century. [80] The tradition of Chinese-Islamic astronomy survived in Korea up until the early nineteenth century. [78]

The first systematic observations in Islam are reported to have taken place under the patronage of al-Mamun. Here, and in many other private observatories from Damascus to Baghdad, meridian degree measurement were performed (al-Ma'mun's arc measurement), solar parameters were established, and detailed observations of the Sun, Moon, and planets were undertaken.

In the tenth century, the Buwayhid dynasty encouraged the undertaking of extensive works in astronomy, such as the construction of a large-scale instrument with which observations were made in the year 950. We know of this by recordings made in the zij of astronomers such as Ibn al-Alam. The great astronomer Abd Al-Rahman Al Sufi was patronised by prince Adud o-dowleh, who systematically revised Ptolemy's catalogue of stars. Sharaf al-Daula also established a similar observatory in Baghdad. Reports by Ibn Yunus and al-Zarqall in Toledo and Cordoba indicate the use of sophisticated instruments for their time.

It was Malik Shah I who established the first large observatory, probably in Isfahan. It was here where Omar Khayyám with many other collaborators constructed a zij and formulated the Persian Solar Calendar a.k.a. the jalali calendar. A modern version of this calendar is still in official use in Iran today.

The most influential observatory was however founded by Hulegu Khan during the thirteenth century. Here, Nasir al-Din al-Tusi supervised its technical construction at Maragha. The facility contained resting quarters for Hulagu Khan, as well as a library and mosque. Some of the top astronomers of the day gathered there, and from their collaboration resulted important modifications to the Ptolemaic system over a period of 50 years.

In 1420, prince Ulugh Beg, himself an astronomer and mathematician, founded another large observatory in Samarkand, the remains of which were excavated in 1908 by Russian teams.

And finally, Taqi al-Din Muhammad ibn Ma'ruf founded a large observatory in Ottoman Constantinople in 1577, which was on the same scale as those in Maragha and Samarkand. The observatory was short-lived however, as opponents of the observatory and prognostication from the heavens prevailed and the observatory was destroyed in 1580. [81] While the Ottoman clergy did not object to the science of astronomy, the observatory was primarily being used for astrology, which they did oppose, and successfully sought its destruction. [82]

As observatory development continued, Islamicate scientists began to pioneer the planetarium. The major difference between a planetarium and an observatory is how the universe is projected. In an observatory, you must look up into the night sky, on the other hand, planetariums allow for universes planets and stars to project at eye-level in a room. Scientist Ibn Firnas, created a planetarium in his home that included artificial storm noises and was completely made of glass. Being the first of its kind, it very similar to what we see for planetariums today.

Our knowledge of the instruments used by Muslim astronomers primarily comes from two sources: first the remaining instruments in private and museum collections today, and second the treatises and manuscripts preserved from the Middle Ages. Muslim astronomers of the "Golden Period" made many improvements to instruments already in use before their time, such as adding new scales or details.

Celestial globes and armillary spheres Edit

Celestial globes were used primarily for solving problems in celestial astronomy. Today, 126 such instruments remain worldwide, the oldest from the 11th century. The altitude of the Sun, or the Right Ascension and Declination of stars could be calculated with these by inputting the location of the observer on the meridian ring of the globe. The initial blueprint for a portable celestial globe to measure celestial coordinates came from Spanish Muslim astronomer Jabir ibn Aflah (d. 1145). Another skillful Muslim astronomer working on celestial globes was ‘Abd al-Rahman al-Sufi(b. 903), whose treatise describes how to design the constellation images on the globe, as well as how to use the celestial globe. However, it was in Iraq in the 10th century that astronomer Al-Battani was working on celestial globes to record celestial data. This was different because up until then, the traditional use for a celestial globe was as an observational instrument. Al-Battani’s treatise describes in detail the plotting coordinates for 1,022 stars, as well as how the stars should be marked. An armillary sphere had similar applications. No early Islamic armillary spheres survive, but several treatises on "the instrument with the rings" were written. In this context there is also an Islamic development, the spherical astrolabe, of which only one complete instrument, from the 14th century, has survived.

Astrolabes Edit

Brass astrolabes were an invention of Late Antiquity. The first Islamic astronomer reported as having built an astrolabe is Muhammad al-Fazari (late 8th century). [83] Astrolabes were popular in the Islamic world during the "Golden Age", chiefly as an aid to finding the qibla. The earliest known example is dated to 927/8 (AH 315).

The device was incredibly useful, and sometime during the 10th century it was brought to Europe from the Muslim world, where it inspired Latin scholars to take up a vested interest in both math and astronomy. [84] Despite how much we know much about the tool, many of the functions of the device have become lost to history. Although it is true that there are many surviving instruction manuals, historians have come to the conclusion that there are more functions of specialized astrolabes that we do not know of. [85] One example of this is an astrolabe created by Nasir al-Din al-Tusi in Aleppo in the year 1328/29 C.E. This particular astrolabe was special and is hailed by historians as the "most sophisticated astrolabe ever made", [86] being known to have five distinct universal uses.

The largest function of the astrolabe is it serves as a portable model of space that can calculate the approximate location of any heavenly body found within the solar system at any point in time, provided the latitude of the observer is accounted for. In order to adjust for latitude, astrolabes often had a secondary plate on top of the first, which the user could swap out to account for their correct latitude. [84] One of the most useful features of the device is that the projection created allows users to calculate and solve mathematical problems graphically which could otherwise be done only by using complex spherical trigonometry, allowing for earlier access to great mathematical feats. [87] In addition to this, use of the astrolabe allowed for ships at sea to calculate their position given that the device is fixed upon a star with a known altitude. Standard astrolabes performed poorly on the ocean, as bumpy waters and aggressive winds made use difficult, so a new iteration of the device, known as a Mariner's astrolabe, was developed to counteract the difficult conditions of the sea. [88]

The instruments were used to read the time of rise of the Sun and fixed stars. al-Zarqali of Andalusia constructed one such instrument in which, unlike its predecessors, did not depend on the latitude of the observer, and could be used anywhere. This instrument became known in Europe as the Saphea.

The astrolabe was arguably the most important instrument created and used for astronomical purposes in the medieval period. Its invention in early medieval times required immense study and much trial and error in order to find the right method of which to construct it to where it would work efficiently and consistently, and its invention led to several mathematic advances which came from the problems that arose from using the instrument. [89] The astrolabe’s original purpose was to allow one to find the altitudes of the sun and many visible stars, during the day and night, respectively. [90] However, they have ultimately come to provide great contribution to the progress of mapping the globe, thus resulting in further exploration of the sea, which then resulted in a series of positive events that allowed the world we know today to come to be. [91] The astrolabe has served many purposes over time, and it has shown to be quite a key factor from medieval times to the present.

The astrolabe, as mentioned before, required the use of mathematics, and the development of the instrument incorporated azimuth circles, which opened a series of questions on further mathematical dilemmas. [89] Astrolabes served the purpose of finding the altitude of the sun, which also meant that they provided one the ability to find the direction of Muslim prayer (or the direction of Mecca). [89] Aside from these perhaps more widely known purposes, the astrolabe has led to many other advances as well. One very important advance to note is the great influence it had on navigation, specifically in the marine world. This advancement is incredibly important because the calculation of latitude being made more simple not only allowed for the increase in sea exploration, but it eventually led to the Renaissance revolution, the increase in global trade activity, even the discovery of several of the world’s continents. [91]

Mechanical calendar Edit

Abu Rayhan Biruni designed an instrument he called "Box of the Moon", which was a mechanical lunisolar calendar, employing a gear train and eight gear-wheels. [92] This was an early example of a fixed-wired knowledge processing machine. [93] This work of Al Biruni uses the same gear trains preserved in a 6th century Byzantine portable sundial. [94]

Sundials Edit

Muslims made several important improvements [ which? ] to the theory and construction of sundials, which they inherited from their Indian and Greek predecessors. Khwarizmi made tables for these instruments which considerably shortened the time needed to make specific calculations.

Sundials were frequently placed on mosques to determine the time of prayer. One of the most striking examples was built in the fourteenth century by the muwaqqit (timekeeper) of the Umayyad Mosque in Damascus, ibn al-Shatir. [96]

Quadrants Edit

Several forms of quadrants were invented by Muslims. Among them was the sine quadrant used for astronomical calculations, and various forms of the horary quadrant, used to determine time (especially the times of prayer) by observations of the Sun or stars. A center of the development of quadrants was ninth-century Baghdad. [97] Abu Bakr ibn al-Sarah al-Hamawi (d. 1329) was a Syrian astronomer that invented a quadrant called “al-muqantarat al-yusra”. He devoted his time to writing several books on his accomplishments and advancements with quadrants and geometrical problems. His works on quadrants include Treatise on Operations with the Hidden Quadrant and Rare Pearls on Operations with the Circle for Finding Sines. These instruments could measure the altitude between a celestial object and the horizon. However, as Muslim astronomers used them, they began to find other ways to use them. For example, the mural quadrant, for recording the angles of planets and celestial bodies. Or the universal quadrant, for latitude solving astronomical problems. The horary quadrant, for finding the time of day with the sun. The almucantar quadrant, which was developed from the astrolabe.

Equatoria Edit

Planetary equatoria were probably made by ancient Greeks, although no findings nor descriptions have been preserved from that period. In his comment on Ptolemy's Handy Tables, 4th century mathematician Theon of Alexandria introduced some diagrams to geometrically compute the position of the planets based on Ptolemy's epicyclical theory. The first description of the construction of a solar (as opposed to planetary) equatorium is contained in Proclus's fifth-century work Hypotyposis, [98] where he gives instructions on how to construct one in wood or bronze. [99]

The earliest known description of a planetary equatorium is contained in early 11th century treatise by Ibn al‐Samḥ, preserved only as a 13th century Castillian translation contained in the Libros del saber de astronomia (Books of the knowledge of astronomy) the same book contains also a 1080/1081 treatise on the equatorium by al-Zarqālī. [99]

There are examples of cosmological imagery throughout many forms of Islamic art, whether that be manuscripts, ornately crafted astrological tools, or palace frescoes, just to name a few. Islamic art maintains the capability to reach every class and level of society.

Within Islamic cosmological doctrines and the Islamic study of astronomy, such as the Encyclopedia of the Brethren of Purity (alternatively called The Rasa'il of the Ikhwan al-Safa) there is a heavy emphasis by medieval scholars on the importance of the study of the heavens. This study of the heavens has translated into artistic representations of the universe and astrological concepts. [100] There are many themes under which Islamic astrological art falls under, such as religious, political, and cultural contexts. [101] It is posited by scholars that there are actually three waves or traditions of cosmological imagery, Western, Byzantine, and Islamic. The Islamic world gleaned inspiration from Greek, Iranian, and Indian methods in order to procure a unique representation of the stars and the universe. [102]

Examples Edit

A place like Quasyr' Amra, which was used as a rural Umayyad palace and bath complex, coveys the way astrology and the cosmos have weaved their way into architectural design. During the time of its use, one could be resting in the bathhouse and gaze at the frescoed dome that would almost reveal a sacred and cosmic nature. Aside from the other frescoes of the complex which heavily focused on al-Walid, the bath dome was decorated in the Islamic zodiac and celestial designs. [101] It would have almost been as if the room was suspended in space. In their encyclopedia, the Ikhwan al' Safa describe the Sun to have been placed at the center of the universe by God and all other celestial bodies orbit around it in spheres. [100] As a result, it would be as if whoever was sitting underneath this fresco would have been at the center of the universe, reminded of their power and position. A place like Qusayr' Amra represents the way astrological art and images interacted with Islamic elites and those who maintained caliphal authority.

The Islamic zodiac and astrological visuals have also been present in metalwork. Ewers depicting the twelve zodiac symbols exist in order to emphasize elite craftsmanship and carry blessings such as one example now at the Metropolitan Museum of Art. [103] Coinage also carried zodiac imagery that bears the sole purpose of representing the month in which the coin was minted. [104] As a result, astrological symbols could have been used as both decoration, and a means to communicate symbolic meanings or specific information.


Thirty Years – Plus

Compiled from articles by Ron Ferdie which appeared November and December 1984 Desert Skies and an update added by Teresa Lappin in 1987 (see below).

  • TUCSON AMATEUR ASTRONOMERS (April 13, 1954 to December 2, 1959)
  • TUCSON ASTRONOMICAL AND ASTRONAUTICAL ASSOCIATION (December 2, 1959 to October 5, 1978)
  • TUCSON AMATEUR ASTRONOMY ASSOCIATION (October 5, 1978 to present)

In March 1954, a small group met at the home of the Earl Burch to talk about organizing interested astronomers into a club. They met again in April, and formed the Tucson Amateur Astronomers (TAA). The first TAA officers were: Earl C. Burch, President Captain John Vega, Vice-President Kathryn Burch, Secretary-Treasurer and Major T.H. Armistead, Executive Board Member. The other charter members where Lloyd Soth, Ed Oxner, C.A. Clemente, J.A. Degennear, N.J. Griffen, R.T. Brockus, V. Gauzeau, S.W. Hvosles, Captain V. Berry, and Prof. Harry Stewart, UA. By the end of the first year there were 46 members.

The first TAA program meeting in May 1954 featured Capt. John Vega talking on the “The Constellation Ursa Major” and T.H. Armstead discussing “Basic Ground Rules of Astronomical Terms”. The first club “star party” was in November 1954 at the home of Earl and Kathryn Burch.

In June 1955, we began the annual tradition pot luck supper and star-gazing party, the first time at Wrightstown School. In 1955 this was a “dark site”.

A telescope makers’ group was started by Earl Burch in 1955 with about fifteen members, and the tradition continues today (ed. 1984) with Duane Niehaus, current TAAA Vice President, for those interested in making mirrors and telescopes.

As a result of the interest of Dr. Edwin F. Carpenter, head of the UA Department of Astronomy, TAA was able to get both his support and University sponsorship of our organization. This included use of the Steward Observatory building for many of our meetings in these early years, and the use of the 36-inch telescope and the smaller telescopes when we did not interfere with the normal scheduled programs. Dr. Carpenter helped the club in many ways, and was a professional inspiration. He was elected an honorary Life Member in 1956, and assisted our club in a number of projects, including Moonwatch for early man-made earth satellites. He passed away in 1962.

A club library was founded from a donation by an anonymous donor in February 1956. Carl Clemente was appointed first Librarian. He and other members presented short book and publication reviews at meetings. The library grew of the years and is now located at the home of Duane Niehaus. Members are invited to inquire on contents and loans.

At this time a committee was formed for club pins and headed by Mrs. Hazel MacCready. The TAA membership selected a design out of a series of designs by Carl Clemente. The first pins were distributed at the September 1956 meeting. When the club changed our name to the Tucson Astronomical and Astronautical Association in November 1959, the pins were redesigned. TAA/TAAA member James Christy, later discoverer of Pluto’s moon Charon in 1978, proudly showed them off when he lectured with Clyde Tombaugh, discoverer of Pluto, at a special meeting in 1983.

Jim, now living in Tucson, also was the club’s first newsletter editor. The first issue of the TAA Star Observer appeared in February 1959. Since then, there have been a number of newsletter formats and editors. In more recent years newsletter editors have included: Gary Hall, Mike Zachary, Rick and Dolores Hill (with the Desert Skies) and now Jim Oliver.

Don Strittmatter was elected club President in 1958, after serving as Vice President to TAA’s second President Earl Sydow. Don held the position of TAA/TAAA president for 19 years, guiding the club through projects, and retiring himself from the job in May 1976. Don Strittmatter and Jim Christy appear to be the earliest members still around (about 28-29 years), along with Ewen Whitaker (about 25 years).

The TAA set up a group for observing artificial earth satellites for the Smithsonian Astrophysical Observatory at the September 1956 meeting. Earl Sydow was the first chairman of the group, originally comprised of approximately 50 members, and eventually organized into several teams. Initial funds for thirteen wide field telescopes and other equipment were made by Hughes Aircraft.

The Tucson Satellite Observing Station (TSOS) was comprised of both TAA/TAAA members and UA astronomy students, and assigned Station Code Number 003-0320111. Leon Campbell, Jr., coordinated efforts with the Tucson station and all other satellite observing stations around the world as Director, Moonwatch Program. The Tucson station was located just south of Steward Observatory. If it looks like a small space now, it shows you how Tucson locale has changed.

The importance of Moonwatch cannot be exaggerated. It helped hone the fledgling science of space flight mechanics before there were sophisticated ground link stations there are today. The TAA/TAAA station achieved a top Prime A national rating, and was considered among the top three stations in the country. By the end of the Moonwatch era there were 160 stations in the U.S., and 280 throughout the world.

The Tucson station began performing more and more complex tasks, including satellite photography. Among special accomplishments were 405 hours of observation by 25 team members from April 9 – 14, 1959, in the reentry death watch” of satellites Beta (Russian Sputnik launched in 1957). At least one member Hal Cozzens, accepted a position to assist the Baker-Nun satellite camera installation at Organ Mountain, Las Cruces, N.M.

In January 1959, active members of the Tucson Amateur Astronomer’s Moonwatch team, along with participating U of Arizona astronomy students, were honored by certificates of recognition from the Smithsonian Astrophysical Observatory. There were a total of 34 certificates given to people such as Don Strittmatter, Jim Christy, and Ed Van Sice. The presentations were made by Earl Sydow, former TAA president and founder of the Moonwatch station, at a meeting at the Steward Observatory near the station.

In addition, 17 TAA members and UofA students were awarded special Moonwatch emblem pins by Convair. Receiving these distinctive pins were: Linda Hearn, Jim Christy, Don Strittmatter, Ed Strittmatter, Dave Odom, Rodger Scherrer, John Mayo, Calvin Harris, Clarence Doubek, Raul Lynn, Carl Clemente, Wayne Sanders, Les Hearn, Earl Sydow, Harold Gass, and Ed Van Sice. An honorary pin was awarded to Dr. Ed Carpenter, then head of UA’s astronomy department and Director to Steward Observatory.

Tucson Amateur Astronomers participated in the International Geophysical Year, and were awarded a certificate later that year. About the same time the club changed their name to the Tucson Astronomical and Astronautical Association because of their current activities. Some believe the name change also came about because the TAA became well enough publicized to cause some confusion with the Tucson Airport Authority.

In 1969, after a series of moves–from the Steward Observatory basement to the 7th Street Optical Shop to a 22nd Street Annex, the TAAA settled in with its equipment and supplies at the newly built UA Optical Sciences Center. The Optical Sciences Center provided space to work in and the pitches, grinding compounds, and barrels. Dr. Meinel, Dr, Noble (then an active TAAA member), Don Loomis, Jim Bailey, and T.S. Byingtion were instrumental in helping the association make its several moves to acquire supplies.

Optician Dick Sumner was instructor at Friday night mirror making sessions along with TAAA president Don Strittmatter. Approximately 40 members participated at this time.

Besides the Friday night telescope making sessions, the TAAA held regular monthly meetings on first Wednesdays at the Steward Observatory Auditorium. TAAA was now 18 years old with 110 dues paying members.

In 1969, some 30 members were involved in the observation of grazing occultations of stars at the edge of the moon’s line of sight. The average graze lasts only a minute or two, and timing accuracies were achieved within one second using WWV. The data from such observations were used to correct parameters of the moon’s orbit and obtain lunar mountain heights. The calculations to determine where the observations were to be made (within fifty feet) were made by Daniel Harris, UA astronomy graduate student. Harris reduced the observations from the tape recordings to usable data and sent them to the Naval Observatory, Washington, D.C., and to H.M. Nautical Almanac Office, Sussex, England.

Today TAAA member Derald Nye–also a member of IOTA–aids in coordinating observations of grazing occultations of stars by the moon’s limb and asteroid occultations of stars which aides in determining size and shape. Derald coordinates with other IOTA members in nearby astronomical clubs for maximum effectiveness. Interested TAAA members may contact him however, he prefers more experienced observers for lunar grazing occultations.

In 1975, the TAAA moved their operations to the newly opened Flandrau Planetarium. The TAAA office and mirror grinding classes occupied a small section of the basement area. Don Strittmatter, Tom Caudell, and others continued to aid people in building their own telescopes. However, the University kept growing, and LPL next gradually got our club’s space. We moved out our remaining furniture this year.

Still, the TAAA has kept its commitment to assist members in grinding tier own mirrors and assembling telescopes through the diligence of Duane Niehuas, our current Vice=President, who has continued to offer this service at his home. Interested members should explore the possibility of making their own telescope by contacting Duane. Duane has now provided this service a number of years now, and TAAA members like Teresa Lappin, Scott Henning, Ray Wallace, Walter Wegrzyn, and many others can attest to the fine assistance and consultation he has provided our club.

It is no wonder, then, that when the Bart And Priscilla Bok Award for proficiency in Tucson area amateur astronomy was inaugurated a few years ago, that Duane was first recipient by Dr. Bok, expert on the Milky Way Galaxy and a close friend of our club. Other recipients of the Bok Award have been Pierre Schwaar and David Levy. Dr. Bok passed away last year.

Returning back to 1975, then President Don Strittmatter obtained an indefinite loan of a 16-inch mirror from PL for the TAAA. Don, Tom Caudell, Gary Hall, and others worked on the project a number of hears. Caudell obtained much of the mounting which was recently reassembled for a new home in an observatory building of Derald Nye’s. It was originally supposed to be a portable to star parties on a trailer mount, but was only taken out a few times.

Space is running out for this short article on our history, but not the history itself–that we are all participants of. The TAAA–your club–is now considering a 30-inch lightweight mirror project Michael Sweetman just won the LOGO contest Mike Smith has just started a TAAA column in the Sunday Arizona Star Tim Hunter, Dan Knauss, and others getting us officially registered as a non-profit organization Rick Hill as ALPO Solar Section Recorder coordinating a world-wide network of solar activity reports David Levy just discovered his first comet Levy-Rudenko and …


Contents

In 1913, the chemist Lawrence Joseph Henderson (1878–1942) wrote The Fitness of the Environment, one of the first books to explore concepts of fine tuning in the universe. Henderson discusses the importance of water and the environment with respect to living things, pointing out that life depends entirely on the very specific environmental conditions on earth, especially with regard to the prevalence and properties of water. [7]

In 1961, physicist Robert H. Dicke claimed that certain forces in physics, such as gravity and electromagnetism, must be perfectly fine-tuned for life to exist in the universe. [8] [9] Fred Hoyle also argued for a fine-tuned universe in his 1984 book The Intelligent Universe. "The list of anthropic properties, apparent accidents of a non-biological nature without which carbon-based and hence human life could not exist, is large and impressive", Hoyle wrote. [10]

Belief in the fine-tuned universe led to the expectation that the Large Hadron Collider (LHC) would produce evidence of physics beyond the Standard Model, such as supersymmetry, [6] but by 2012 results from the LHC had not produced evidence for supersymmetry at the energy scales it was able to probe. [11]

Physicist Paul Davies has said, "There is now broad agreement among physicists and cosmologists that the Universe is in several respects ‘fine-tuned' for life". However, he continued, "the conclusion is not so much that the Universe is fine-tuned for life rather it is fine-tuned for the building blocks and environments that life requires." He has also said that " 'anthropic' reasoning fails to distinguish between minimally biophilic universes, in which life is permitted, but only marginally possible, and optimally biophilic universes, in which life flourishes because biogenesis occurs frequently". [12] Among scientists who find the evidence persuasive, a variety of natural explanations have been proposed, such as the existence of multiple universes introducing a survivorship bias under the anthropic principle. [1]

The premise of the fine-tuned universe assertion is that a small change in several of the physical constants would make the universe radically different. As Stephen Hawking has noted, "The laws of science, as we know them at present, contain many fundamental numbers, like the size of the electric charge of the electron and the ratio of the masses of the proton and the electron. . The remarkable fact is that the values of these numbers seem to have been very finely adjusted to make possible the development of life." [5]

If, for example, the strong nuclear force were 2% stronger than it is (i.e. if the coupling constant representing its strength were 2% larger) while the other constants were left unchanged, diprotons would be stable according to Davies, hydrogen would fuse into them instead of deuterium and helium. [13] This would drastically alter the physics of stars, and presumably preclude the existence of life similar to what we observe on Earth. The diproton's existence would short-circuit the slow fusion of hydrogen into deuterium. Hydrogen would fuse so easily that it is likely that all the universe's hydrogen would be consumed in the first few minutes after the Big Bang. [13] This "diproton argument" is disputed by other physicists, who calculate that as long as the increase in strength is less than 50%, stellar fusion could occur despite the existence of stable diprotons. [14]

The precise formulation of the idea is made difficult by the fact that we do not yet know how many independent physical constants there are. The standard model of particle physics has 25 freely adjustable parameters and general relativity has one more, the cosmological constant, which is known to be nonzero but profoundly small in value. But because physicists have not developed an empirically successful theory of quantum gravity, there is no known way to combine quantum mechanics, on which the standard model depends, and general relativity. Without knowledge of this more complete theory suspected to underlie the standard model, it is impossible to definitively count the number of truly independent physical constants. In some candidate theories, the number of independent physical constants may be as small as one. For example, the cosmological constant may be a fundamental constant, but attempts have also been made to calculate it from other constants, and according to the author of one such calculation, "the small value of the cosmological constant is telling us that a remarkably precise and totally unexpected relation exists among all the parameters of the Standard Model of particle physics, the bare cosmological constant and unknown physics." [15]

Martin Rees formulates the fine-tuning of the universe in terms of the following six dimensionless physical constants. [2] [16]

  • N, the ratio of the electromagnetic force to the gravitational force between a pair of protons, is approximately 10 36 . According to Rees, if it were significantly smaller, only a small and short-lived universe could exist. [16]
  • Epsilon (ε), a measure of the nuclear efficiency of fusion from hydrogen to helium, is 0.007: when four nucleons fuse into helium, 0.007 (0.7%) of their mass is converted to energy. The value of ε is in part determined by the strength of the strong nuclear force. [17] If ε were 0.006, only hydrogen could exist, and complex chemistry would be impossible. According to Rees, if it were above 0.008, no hydrogen would exist, as all the hydrogen would have been fused shortly after the Big Bang. Other physicists disagree, calculating that substantial hydrogen remains as long as the strong force coupling constant increases by less than about 50%. [14][16]
  • Omega (Ω), commonly known as the density parameter, is the relative importance of gravity and expansion energy in the universe. It is the ratio of the mass density of the universe to the "critical density" and is approximately 1. If gravity were too strong compared with dark energy and the initial metric expansion, the universe would have collapsed before life could have evolved. If gravity were too weak, no stars would have formed. [16][18]
  • Lambda (Λ), commonly known as the cosmological constant, describes the ratio of the density of dark energy to the critical energy density of the universe, given certain reasonable assumptions such as that dark energy density is a constant. In terms of Planck units, and as a natural dimensionless value, Λ is on the order of 10 −122 . [19] This is so small that it has no significant effect on cosmic structures that are smaller than a billion light-years across. A slightly larger value of the cosmological constant would have caused space to expand rapidly enough that stars and other astronomical structures would not be able to form. [16][20]
  • Q, the ratio of the gravitational energy required to pull a large galaxy apart to the energy equivalent of its mass, is around 10 −5 . If it is too small, no stars can form. If it is too large, no stars can survive because the universe is too violent, according to Rees. [16]
  • D, the number of spatial dimensions in spacetime, is 3. Rees claims that life could not exist if there were 2 or 4 dimensions of spacetime nor if the number of time dimensions in spacetime were anything other than 1. [16] Rees argues this does not preclude the existence of ten-dimensional strings. [2]

Carbon and oxygen Edit

An older example is the Hoyle state, the third-lowest energy state of the carbon-12 nucleus, with an energy of 7.656 MeV above the ground level. [21] : 125–127 According to one calculation, if the state's energy level were lower than 7.3 or greater than 7.9 MeV, insufficient carbon would exist to support life. Furthermore, to explain the universe's abundance of carbon, the Hoyle state must be further tuned to a value between 7.596 and 7.716 MeV. A similar calculation, focusing on the underlying fundamental constants that give rise to various energy levels, concludes that the strong force must be tuned to a precision of at least 0.5%, and the electromagnetic force to a precision of at least 4%, to prevent either carbon production or oxygen production from dropping significantly. [22]

Some explanations of fine-tuning are naturalistic. [23] : 125 First, the fine-tuning might be an illusion: more fundamental physics may explain the apparent fine-tuning in physical parameters in our current understanding by constraining the values those parameters are likely to take. As Lawrence Krauss puts it, "certain quantities have seemed inexplicable and fine-tuned, and once we understand them, they don’t seem to so fine-tuned. We have to have some historical perspective." [20] Some argue it is possible that a final fundamental theory of everything will explain the underlying causes of the apparent fine-tuning in every parameter. [24] [20]

Still, as modern cosmology developed, various hypotheses not presuming hidden order have been proposed. One is a multiverse, where fundamental physical constants are postulated to have different values outside of our own universe. [25] [26] : 3–33 On this hypothesis, separate parts of reality would have wildly different characteristics. In such scenarios, the appearance of fine-tuning is explained as a consequence of the weak anthropic principle and selection bias (specifically survivor bias) only those universes with fundamental constants hospitable to life (such as ours) could contain life forms capable of observing the universe and contemplating the question of fine-tuning in the first place. [27]

Multiverse Edit

If the universe is just one of many, each with different physical constants, it would be unsurprising that we find ourselves in a universe hospitable to intelligent life (see multiverse: anthropic principle). Some versions of the multiverse hypothesis therefore provide a simple explanation for any fine-tuning. [1]

The multiverse idea has led to considerable research into the anthropic principle and has been of particular interest to particle physicists, because theories of everything do apparently generate large numbers of universes in which the physical constants vary widely. As yet, there is no evidence for the existence of a multiverse, but some versions of the theory make predictions of which some researchers studying M-theory and gravity leaks hope to see some evidence soon. [28] UNC-Chapel Hill professor Laura Mersini-Houghton claimed that the WMAP cold spot could provide testable empirical evidence for a parallel universe, [29] but this was later refuted as the WMAP cold spot was found to be nothing more than a statistical artifact. [30] Variants of this approach include Lee Smolin's notion of cosmological natural selection, the Ekpyrotic universe, and the Bubble universe theory.

Top-down cosmology Edit

Stephen Hawking and Thomas Hertog proposed that the universe's initial conditions consisted of a superposition of many possible initial conditions, only a small fraction of which contributed to the conditions we see today. [31] On their theory, it is inevitable that we find our universe's "fine-tuned" physical constants, as the current universe "selects" only those past histories that led to the present conditions. In this way, top-down cosmology provides an anthropic explanation for why we find ourselves in a universe that allows matter and life, without invoking the ontic existence of the Multiverse. [32]

Carbon chauvinism Edit

Some forms of fine-tuning arguments about the formation of life assume that only carbon-based life forms are possible, an assumption sometimes called carbon chauvinism. [33] Conceptually, alternative biochemistry or other forms of life are possible. [34]

Alien design Edit

One hypothesis is that extra-universal aliens designed the universe. Some believe this would solve the problem of how a designer or design team capable of fine-tuning the universe could come to exist. [35] Cosmologist Alan Guth believes humans will in time be able to generate new universes. [36] By implication, previous intelligent entities may have generated our universe. [37] This idea leads to the possibility that the extra-universal designer/designers are themselves the product of an evolutionary process in their own universe, which must therefore itself be able to sustain life. It also raises the question of where that universe came from, leading to an infinite regress.

John Gribbin's Designer Universe theory suggests that an advanced civilization could have deliberately made the universe in another part of the Multiverse, and that this civilization may have caused the Big Bang. [38]

Some scientists, theologians, and philosophers, as well as certain religious groups, argue that providence or creation are responsible for fine-tuning. [39] [40] [41] [42] [43]

Christian philosopher Alvin Plantinga argues that random chance, applied to a single and sole universe, only raises the question as to why this universe could be so "lucky" as to have precise conditions that support life at least at some place (the Earth) and time (within millions of years of the present).

One reaction to these apparent enormous coincidences is to see them as substantiating the theistic claim that the universe has been created by a personal God and as offering the material for a properly restrained theistic argument—hence the fine-tuning argument. It's as if there are a large number of dials that have to be tuned to within extremely narrow limits for life to be possible in our universe. It is extremely unlikely that this should happen by chance, but much more likely that this should happen, if there is such a person as God.

Philosopher and Christian apologist William Lane Craig cites this fine-tuning of the universe as evidence for the existence of God or some form of intelligence capable of manipulating (or designing) the basic physics that governs the universe. Craig argues "that the postulate of a divine Designer does not settle for us the religious question." [45]

Philosopher and theologian Richard Swinburne reaches the design conclusion using Bayesian probability. [46]

Scientist and theologian Alister McGrath has pointed out that the fine-tuning of carbon is even responsible for nature's ability to tune itself to any degree.

The entire biological evolutionary process depends upon the unusual chemistry of carbon, which allows it to bond to itself, as well as other elements, creating highly complex molecules that are stable over prevailing terrestrial temperatures, and are capable of conveying genetic information (especially DNA). […] Whereas it might be argued that nature creates its own fine-tuning, this can only be done if the primordial constituents of the universe are such that an evolutionary process can be initiated. The unique chemistry of carbon is the ultimate foundation of the capacity of nature to tune itself. [47] [48]

Theoretical physicist and Anglican priest John Polkinghorne has stated: "Anthropic fine tuning is too remarkable to be dismissed as just a happy accident." [49]


Question about the relevant physical parameters to build a backyard observatory - Astronomy

Intense geomagnetic storms are caused by coronal mass ejections (CMEs) from the Sun and their forecast is quite important in protecting space- and ground-based technological systems. The onset and strength of geomagnetic storms depend on the kinematic and magnetic properties of CMEs. Current forecast techniques mostly use solar wind in-situ measurements that provide only a short lead time. On the other hand, techniques using CME observations near the Sun have the potential to provide 1-3 days of lead time before the storm occurs. Therefore, one of the challenging issues is to forecast interplanetary magnetic field (IMF) southward components and hence geomagnetic storm strength with a lead-time on the order of 1-3 days. We are going to answer the following three questions: (1) when does a CME arrive at the Earth? (2) what is the probability that a CME can induce a geomagnetic storm? and (3) how strong is the storm? To address the first question, we forecast the arrival time and other physical parameters of CMEs at the Earth using the WSA-ENLIL model with three CME cone types. The second question is answered by examining the geoeffective and non-geoeffective CMEs depending on CME observations (speed, source location, earthward direction, magnetic field orientation, and cone-model output). The third question is addressed by examining the relationship between CME parameters and geomagnetic indices (or IMF southward component). The forecast method will be developed with a three-stage approach, which will make a prediction within four hours after the solar coronagraph data become available. We expect that this study will enable us to forecast the onset and strength of a geomagnetic storm a few days in advance using only CME parameters and the physics-based models.


Peering into space with the Morocco Oukaïmeden Observatory

Moroccan scientific production in astronomy and astrophysics has shown sustained growth since the late 1980s. This growth is largely due to the dynamism of an increasingly entrepreneurial community and to the creation of an astronomical observatory in the Moroccan Atlas Mountains.

The success of this observatory goes back to 1986 when several Moroccan astronomers decided to form a research group at the National Center of Scientific Research in Rabat, the capital of Morocco. Their efforts focused mainly on the development of an astronomical observatory for Morocco as a tool for developing astronomy research and science in general. Toward this end, they initially relied on international cooperation in the seismic study of the Sun. Helioseismology, which probes the internal structure of the Sun by means of its global vibrations, started in Morocco in the late 1970s through a collaboration with a team from the University of Nice, who successfully made the first identification of individual ‘musical’ frequencies from the Sun’s south pole. It was quickly clear that the development of this new research field needed close international collaboration to obtain continuous measurements and analysis of the solar vibrations for many years. In this context, a worldwide network of observational stations was established in the 1980s. Space observations also allow continuous observations of the Sun without interruption. A Moroccan team was associated with both of these approaches. The International Research on the Interior of the Sun (IRIS) network included a station at Oukaïmeden, and it was operated for a complete 11-year solar cycle of magnetic activity, from 1990 to 2001. A complete issue of the journal Solar Physics was devoted to IRIS in 1991 and contains a description of the Moroccan participation 3 . In parallel, the Global Oscillations at Low Frequency (GOLF) space instrument was developed and launched on the ESA/NASA SOHO space observatory in 1995. The first publication provided by this instrument had a Moroccan researcher as its first author 4 . Today, after 22 years of operation, this instrument has provided very high-quality data, which have enabled the detection of the signature of tiny vibrations located deep inside the solar core, called g-modes, through the perturbations that they produce on the Sun’s ‘musical sounds’. This recent result has already led to the measurement of the rapid rotation of the solar core 5 .