Are there any unmanned large telescopes located on Earth?

Are there any unmanned large telescopes located on Earth?

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I just read the answers to the question "Why are all space observatories in Chile?". In addition to the reasons provided, one of the answers also mentions that

… if the telescope should be manned by humans permanently, it cannot be located to high due to the difficulty for humans to function at extremely high altitudes,…

Which leads to my question:

Are there any unmanned large telescopes located on Earth?

I realize that, even if large telescopes are unmanned, they probably need to be serviced by humans on a regular basis. But are humans needed permanently on site?

I also realize that, even though there are humans monitoring the measurements from space telescopes, space telescopes are unmanned in the sense that there are no people at the space telescopes manning them.

The largest "robotic" (i.e., unmanned) telescope I'm aware of is the 2.4-meter Automated Planet Finder. Other large robotic telescopes include the 2.0-meter Liverpool Telescope and its copies (Faulkes Telescope North and Faulkes Telescope South). You can read about the automated control system of the Liverpool telescope here.

These are all located at existing observatories (e.g., APF at Lick Observatory, Liverpool Telescope at Observatorio del Roque de los Muchachos, La Palma, Canary Islands, Spain), which means there are people on site for potential maintenance work, etc., though said staff are really devoted to working on other telescopes.

The closest thing to an isolated, automatic telescope in an uninhabitable setting might be the small (0.5-m) Antarctic Survey Telescope at Dome A in Antarctica, which I believe is serviced annually by Chinese expeditions. It can apparently be remotely controlled via Iridium satellite communications, though actually retrieving the full data sets is part of what the annual expeditions are for.

In addition to @PeterErwin's answer, there is the Himalayan Chandra Telescope (2m), located near the Indian Astronomical Observatory at Hanle at 4500m altitude but operated remotely from near Bangalore.

If you want to leave the realm of optical astronomy, the ALMA telescope array is located at 5000m altitude in the Atacama desert in Chile and operated from a nearby support facility located at an altitude of 2900m. Access to the array itself is kept minimal due to the extreme altitude.

Largest telescopes on Earth

In astronomy we never see this but the past. We see the Moon, a second later, the Sun, eight minutes after the most nearest star, four years later, the most distant galaxy 10 billion years after.
The telescopes are machines back in time.
A telescope is an optical instrument that increases the brightness of the observed object in order to magnify the image. Its role as receiver of light is often more important than the magnification. Ground-based telescopes are, by definition, located on land and are mainly used in astronomy. They are equipped with reflectors mirrors coupled with various cameras and spectrometers to narrow field for faint objects, wide field and planetary images for infrared cameras. The older generation of telescopes of 6 meters in diameter using deformable mirrors not monolithic, very thick and very heavy. Future telescopes that pave the way for a new era of modern astronomy, using the opportunity to continuously monitor the deformations of monolithic mirrors or segmented, flexible and thus deformable under the action of gravity, wind, thermal effects, etc.

The technological limit of about 8 meters in diameter for a large monolithic mirror still prevails but the segmentation allows for giant telescopes, beyond 10 meters. The first light is expected in 2018 with the EELT, European Extremely Large Telescope. The new generation of giant telescopes on the horizon is.
- The Great Magellan Telescope (UTC) US-Australian will have a mirror 21 meters.
- The Thirty Meter Telescope (TMT) built by the Americans and Canadians will include a mirror 30 meters.
- Europeans have opted for the European Extremely Large Telescope (EELT), with a mirror 39.3 meters consisting of more than a thousand segments whose construction should begin in 2015.

Image: Co-financed by the EU, the European E-ELT telescope "European Extremely Large Telescope" should have a budget of around 1 billion euros for the European Southern Observatory (ESO) to build this telescope revolutionary with a mirror 39.3 meters in diameter, which will enter service in 2024-2026.

Largest radio telescopes in the world

Largest radio telescopes in the world are used by professional radio astronomers, and often you can also visit them. Radio telescopes are extraordinary instruments, equipped with giant parabolic antennas or other, designed to work as single instruments or as interferometers. They are used to study objects in the Universe in radio waves frequencies but often are also used for satellite communication or studies of Earth’s atmosphere. Here you have a list with some of the largest radio telescopes in the world and a brief description for each instrument.

Very Large Array – VLA (USA)
Probably one of the most famous radio telescopes in the world thanks to films like “Contact”, it uses 27 Cassegrain antennas each 25 meters diameter that can be moved along a Y shaped rail system.

Largest radio telescopes: VLA (Credit: Alex Savello)

Arecibo (Puerto Rico)
Up to 2016, it was the largest parabolic antenna in the world, thanks to its 305 meters diameter. The antenna was placed on a natural depression in the ground and it has no mount: the radio telescope can point different sky regions moving the central feedhorn.

Largest radio telescopes: Arecibo (Credit: Arecibo Observatory)

The Robert C. Byrd Green Bank radio telescope has a parabolic antenna with asymmetric surface and an off-axis illumination. In Green Bank there are also other large radio telescopes such as the 43-meter diameter one with equatorial mount.

Largest radio telescopes: GBT (Credit: NRAO/AUI/NSF)

Atacama Large Millimeter/submillimeter Array – ALMA (Chile)
The ALMA radio telescope includes many 7 and 12 meters diameter parabolic antennas that have been installed in Atacama desert in Chile, about 5000 meters above sea level. Thus, it will study also the high radio frequencies usually blocked by the atmosphere.

Largest radio telescopes: ALMA (Credit: NRAO/AUI/NSF)

FAST (China)
The Five-hundred-meter Aperture Spherical radio Telescope (FAST)) is a radio telescope located in southwest China. It consists of a fixed 500 m diameter dish constructed in a natural depression in the landscape and it is the world’s largest filled-aperture radio telescope.

Largest radio telescopes: FAST (Credit LIU XU)

Effelsberg (Germany)
Thanks to the huge 100 meters diameter parabolic antenna, this is one of the largest radio telescopes in the world. This radio telescope weighs 3200 tons and it takes 12 minutes to make a complete 360 degrees rotation.

Largest radio telescopes: Effelsberg (Photo by CEphoto, Uwe Aranas)

Medicina (Italy)
Near Bologna there are two radio telescopes: the “Northern Cross” that consists of an array of antennas in two perpendicular arms and a 32 meters diameter parabolic antenna which is also used in interferometric observations.

Largest radio telescopes: Medicina (Credits: Filippo Bradaschia)

Sardinia Radio Telescope (Italy)
This radio telescope, built 35 kilometers away from Cagliari, uses a 64 meters diameter parabolic antenna designed with high accuracy (among the best of several radio telescopes in the world) in order to allow recording at high frequencies (up to 100 GHz).

Largest radio telescopes: SRT (Credits: INAF)

Lovell Radio telescope (England)
With its 76 meters diameter antenna, this instrument is one of the largest radio telescopes in the world with movable reflector. It is located in Jodrell Bank (England) and it’s part of English MERLIN interferometer system.

Largest radio telescopes: Lovell (Credits: Mike Peel Jodrell Bank Centre for Astrophysics, University of Manchester)

Parkes (Australia)
Parkes Observatory is located in the south-eastern Australia and it uses a great 64 meters diameter parabolic antenna. In addition to radio astronomy, it was also used to collect the Apollo 11 transmissions coming from the Moon.

Largest radio telescopes: Parkes (Credits: Stephen West)

Square Kilometer Array – SKA
Currently under study, it uses a network of thousands of antennas installed both in Australia and in South Africa. Combining the recorded signals, it will be possible to obtain a collecting area equivalent to the one of 1 square kilometer parabolic antenna.


Significantly predating the current observatories there is evidence of active astronomy on Mauna Kea in the 1901 Land Office Map of the Island of Hawaii showing the "Hawaii Astronomy Station" near the Mauna Kea summit.

After studying photos for NASA's Apollo program that contained greater detail than any ground-based telescope, Gerard Kuiper began seeking an arid site for infrared studies. [3] [4] While he first began looking in Chile, he also made the decision to perform tests in the Hawaiian Islands. Tests on Maui's Haleakalā were promising, but the mountain was too low in the inversion layer and often covered by clouds. On the "Big Island" of Hawaiʻi, Mauna Kea is considered the highest island mountain in the world. While the summit is often covered with snow, the air is extremely dry. [3] Kuiper began looking into the possibility of an observatory on Mauna Kea. After testing, he discovered the low humidity was perfect for infrared signals. He persuaded Hawaiʻi Governor John A. Burns to bulldoze a dirt road to the summit where he built a small telescope on Puʻu Poliʻahu, a cinder cone peak. [3] [5] [6] The peak was the second highest on the mountain with the highest peak being holy ground, so Kuiper avoided it. [7] : 25 Next, Kuiper tried enlisting NASA to fund a larger facility with a large telescope, housing and other needed structures. NASA, in turn decided to make the project open to competition. Professor of physics, John Jefferies of the University of Hawaii placed a bid on behalf of the university. [3] [8] [9] Jefferies had gained his reputation through observations at Sacramento Peak Observatory. The proposal was for a two-meter telescope to serve both the needs of NASA and the university. While large telescopes are not ordinarily awarded to universities without well-established astronomers, Jefferies and UH were awarded the NASA contract, infuriating Kuiper, who felt that "his mountain" had been "stolen" from him. [3] [10] Kuiper would abandon his site (the very first telescope on Mauna Kea) over the competition and begin work in Arizona on a different NASA project. After considerable testing by Jefferies' team, the best locations were determined to be near the summit at the top of the cinder cones. Testing also determined Mauna Kea to be superb for nighttime viewing due to many factors, including the thin air, constant trade winds and being surrounded by sea. Jefferies would build a 2.24 meter telescope with the State of Hawaiʻi agreeing to build a reliable, all weather roadway to the summit. Building began in 1967 and first light was seen in 1970. [3]

Other groups began requesting subleases on the newly accessible mountaintop. By 1970, two 24 in (0.6 m) telescopes had been constructed by the United States Air Force and Lowell Observatory. In 1973, Canada and France agreed to build the 3.6 m CFHT on Mauna Kea. [11] However, local organizations started to raise concerns about the environmental impact of the observatory. This led the Department of Land and Natural Resources to prepare an initial management plan, drafted in 1977 and supplemented in 1980. In January 1982, the University of Hawaiʻi Board of Regents approved a plan to support the continued development of scientific facilities at the site. [12] In 1998, 2,033 acres (823 ha) were transferred from the observatory lease to supplement the Mauna Kea Ice Age Reserve. The 1982 plan was replaced in 2000 by an extension designed to serve until 2020: it instituted an Office of Mauna Kea Management, [13] designated 525 acres (212 ha) for astronomy, and shifted the remaining 10,763 acres (4,356 ha) to "natural and cultural preservation". This plan was further revised to address concern expressed in the Hawaiian community that a lack of respect was being shown toward the cultural value the mountain embodied to the region's indigenous people. [12]

As of 2012 [update] , the Mauna Kea Science Reserve has 13 observation facilities, each funded by as many as 11 countries. It is one of the world's premier observatories for optical, infrared, and submillimeter astronomy, and in 2009 was the largest measured by light gathering power. [14] There are nine telescopes working in the visible and infrared spectrum, three in the submillimeter spectrum, and one in the radio spectrum, with mirrors or dishes ranging from 0.9 to 25 m (3 to 82 ft). [15] In comparison, the Hubble Space Telescope has a 2.4 m (7.9 ft) mirror, similar in size to the UH88, now the second smallest telescope on the mountain. [15]

Controversies Edit

Planned new telescopes, including the Thirty Meter Telescope, have attracted controversy due to their potential cultural and ecological impact. [16] [17] The multi-telescope "outrigger" extension to the Keck telescopes, which required new sites, was eventually canceled. [18] Three or four of the mountain's 13 existing telescopes must be dismantled over the next decade with the TMT proposal to be the last area on Mauna Kea on which any telescope would ever be built. [19]

The Reserve was established in 1968, and is leased by the State of Hawaiʻi's Department of Land and Natural Resources (DLNR). [20] The University of Hawaiʻi manages the site [20] and leases land to several multi-national facilities, which have invested more than $2 billion in science and technology. [1] The lease expires in 2033 and after that 40 of 45 square kilometers (25 of 28 square miles) revert to the state of Hawaii. [19]

The altitude and isolation in the middle of the Pacific Ocean makes Mauna Kea one of the best locations on earth for ground-based astronomy. It is an ideal location for submillimeter, infrared and optical observations. The seeing statistics show that Mauna Kea is the best site in terms of optical and infrared image quality for example, the CFHT site has a median seeing of 0.43 arcseconds.

Accommodations for research astronomers are located at the Onizuka Center for International Astronomy (often called Hale Pōhaku), 7 miles (11 km) by unpaved steep road from the summit at 9,300 feet (2,800 m) above sea level.

An adjacent visitor information station is located at 9,200 feet (2,800 m). The summit of Mauna Kea is so high that tourists are advised to stop at the visitor station for at least 30 minutes to acclimate to atmospheric conditions before continuing to the summit, and scientists often stay at Hale Pōhaku for eight hours or more before spending a full night at observatories on the summit, with some telescopes requiring observers to spend one full night at Hale Pōhaku before working at the summit.

Inside the Gran Telescopio Canarias. Photograph: Image Professionals GmbH/Alamy

Located 2,267 metres (7,438ft) above sea level in La Palma, Canary Islands, the Gran Telescopio Canarias is currently the world’s largest single aperture telescope. In 2016, it obtained an image of a galaxy 500 million light years away, 10 times deeper into space than any other telescope could have observed from the ground.

List of largest optical refracting telescopes

Refracting telescopes use a lens to focus light. The largest practical functioning refracting telescope is the Swedish 1-m Solar Telescope, which is used today for solar observations. Second is the Yerkes Observatory 40 inch (102 cm) refractor, used for astronomical and scientific observation for over a century, and the next biggest is the James Lick telescope, and the Meudon Great Refractor. [1]

Most are classical great refractors, which used achromatic doublets on an equatorial mount. However, other large refractors include a 21st-century solar telescope which is not directly comparable because it uses a single element non-achromatic lens, and the short-lived Great Paris Exhibition Telescope of 1900. It used a 78-inch (200 cm) Focault siderostat for aiming light into the Image-forming optical system part of the telescope, which had a 125 cm diameter lens. Using a siderostat incurs a reflective loss. Larger meniscus lenses have been used in later catadioptric telescopes which mix refractors and reflectors in the image-forming part of the telescope. As with reflecting telescopes, there was an ongoing struggle to balance cost with size, quality, and usefulness.

This list includes some additional examples, such as the Great Paris telescope, which also used a mirror, and some solar telescopes which may have more complicated optical configurations. The SST has an optical aperture of 98 cm (39.37"), although the lens itself is 110 cm (43.31"). It is a single element lens whereas most of this list are doublets, with a crown and flint lens elements.

Chile And Telescopes Are A Match Made In Heaven

On July 2, the path of a total solar eclipse took it over the Cerro Tololo Inter-American Observatory. Even though that observatory is designed to study the night sky, it nonetheless made an idea spot to watch the Moon's shadow sweep east across the nearby Pacific Ocean.

While in Chile to cover the eclipse, I decided to visit some of the many other observatories that have made their home in the Chilean mountains. I picked three. Here's a snapshot of what they do and what makes them so valuable to the worlds of astronomy and astrophysics.

The Atacama Large Millimeter Array (ALMA)

The ALMA telescopes look like large steerable satellite dishes. The dishes aren't all packed together. Any two of them can be as much as 10 miles apart.

They're in a part of the Atacama Desert that's about 16,000 feet above sea level. The thin air there makes it hard for humans to work, so ALMA's main control room is at a lower altitude, a mere 9,500 feet above sea level.

"In the control room what we do is to operate the telescope the Alma Observatory" says ALMA astronomer Ignacio Toledo. Operating the telescope means deciding what the dishes are pointing at and monitoring atmospheric conditions, especially the amount of water vapor.

ALMA can see radiation coming from things like dust and gas, but water vapor acts like a cloud blocking the signal.

Toledo says more astronomers want to use ALMA than the facility can accommodate each year.

"In total, they were requesting around 16,000 hours, and we can only give 4,000," he says. "So they do a selection based on the scientific merits of the project."

The day I was there, David Principe, an astronomer at the MIT Kavli Institute for Astrophysics and Space Research, was the lucky winner.

Principe had ALMA point to a bright young star because he studies star formation.

In those early stages, the star is surrounded by a thick ring of dust, something that ALMA is particularly good at seeing.

"This ring is ultimately where planets are forming," Principe says. You can't actually see the planet, but you can see a gap in the ring where the planet's gravity has cleared away the material.

Like almost all of ALMA's users, Principe didn't travel to the observatory when his measurements were being made. At some point, he'll receive a large data file containing his results that he can study on a computer in his office.

ALMA astronomer Ignacio Toledo says this remote capability takes some of the magic out of observing with a telescope.

"It's less romantic, yes," Toledo says. "But at least for me and I think for most of the people here, they work in this feeling that what we're doing is something awesome."

The Cosmology Large Angular Scale Surveyor (CLASS)

CLASS is located on top of Cerro Toco in the Atacama Desert, one of the driest places on Earth. And at roughly 17,000 feet above sea level, it's one of the highest telescopes in the world.

"The No. 1 science goal of CLASS is to detect evidence for these quantum gravitational waves," says Tobias Marriage, an astronomer at Johns Hopkins University and one of the principal scientists on CLASS.

I interviewed Jullianna Couto (right), site manager for the Cosmology Large Angular Scale Surveyor, on top of Cerro Toco in the Atacama Desert. Tobias Marriage/Tobias Marriage/Johns Hopkins University hide caption

Earth-hunter telescope prepared for launch

NASA unveiled a modest telescope on Friday with a sweeping mission — to discover if there are any Earth-type planets orbiting distant stars.

Though astronomers have found more than 330 planets circling stars in other solar systems, none has the size and location that is believed to be key to supporting life.

"A null result is as important as finding planets," Michael Bicay, director of science at NASA's Ames Research Center in California, told reporters in Titusville, Florida, where the Kepler telescope is being prepared for launch.

Named after the 17th century astronomer who figured out the motions of planets, Kepler is scheduled for liftoff on March 5 aboard an unmanned Delta 2 rocket from the Cape Canaveral Air Force Station.

Once in position trailing Earth in orbit, Kepler will spend at least 3 1/2 years focused on a star-rich patch of sky between the constellations Cygnus and Lyra.

Equipped with a 95 megapixel camera -- the largest ever flown in space -- Kepler will attempt to find Earth-sized planets flying across the face of their parent stars.

Scientists say it will be a bit like trying to spot a gnat in the glare of a floodlight.

To an outside observer, a planet as large as Jupiter temporarily blots out about 1 percent of visible light from the sun as it makes its transit. Passage of Earth-like worlds produce a change in brightness of about 84 parts in a million.

February 25th: Where’s the Best Place for the Biggest Telescopes?

Title: Where’s the Best Place for the Biggest Telescopes?

Podcaster: Rob Berthiaume

Description: Scientists and engineers spend millions of dollars and many years deciding what kind of telescope to build and how to build it. With such an investment, they also put a lot of thought into where they put it. In today’s podcast, Robert goes over the few key things they consider when deciding where to put their telescope in order to ensure they get the best performance out of it once it’s built.

Bio: Robert Berthiaume is a graduate student at York University in Toronto, Canada. When not working in the atomic research lab towards his MSc in Physics, you can probably find him at the university’s observatory, where he is allowed to use a telescope that the bank says he is definitely not allowed to buy.

Today’s sponsor: This episode of � Days of Astronomy” is sponsored by David Gwyn in honor of his wife Andrea’s brithday, who has given him the universe and shares and supports his love for the night sky. Learn more at Happy birthday, Andrea!

This episode of � Days of Astronomy” has also been sponsored by Tom Foster.

Hi there. I’m Robert Berthiaume bringing you the February 25th edition of the 365 Days of Astronomy Podcast. I’m coming to you from the York University Observatory in located in Toronto, Canada. Here at the dome, we get lots of visitors in the form of cub scouts, girl guides, school groups, university students, and the general public. While showing off our telescopes and the sights we can see through them, a few questions come up every time, no matter the age or background of the audience. We inevitably get asked about black holes, the moon landings, 2012, and how big the biggest telescope is and where it is? The answers: No, we won’t be able to look at a black hole this evening, no, the moon landings weren’t faked, no, the 2012 doomsday scare has no scientific or astronomical evidence supporting it, and lastly, well, that answer is a bit longer. It’s the subject of today’s podcast: where on Earth are the biggest telescopes?

The world’s largest telescopes have mirrors that are 8 to 10 meters across. They require precise optical configuration, the latest in cameras, spectrographs, and other instruments, complex dome enclosures, and more. They cost hundreds of millions of dollars and years to build, so when we build one, we think very carefully about where to put it. There are 4 big things to consider when deciding where to put our biggest telescopes.

It goes without saying that the best time to observe the stars is during the night, and obviously that’s because during the night it’s dark. So that’s our first big concern in deciding where to put our telescope. We need to make sure it’ll be dark where we’re observing. Now with the exception of being around the North or South Poles during their local summers, there’s always a night time anywhere else on the globe, so we’re guaranteed some natural darkness anywhere we put our telescopes on Earth. But in the last little while us humans have figured out how to build cities and light bulbs, and when you put the two together, you get light pollution. This is all the light that bounces up into the atmosphere from buildings, streetlights, signs, and makes the sky look brighter in the city than in the country. This makes it harder to see stars, and to collect good observations, so we’ll want to keep our telescope far away from city lights. The astronomers might have to commute a bit further to get to work, but it pays off in better observations.

The next thing that’s important to consider is the altitude of the observatory, or how high it is. We want to avoid putting the telescope at lower altitudes, like at sea level, and instead place it high up, like on the top of a mountain. You might initially think that this is so the telescope is closer to the stars so we can get a better look at them, but a change of a few thousand meters here on Earth doesn’t make a difference when we’re looking at things that are trillions of kilometers away. It actually has to do with something astronomers call ‘seeing’. You all know that there is a blanket of air surrounding Earth, called the atmosphere. And whenever you’re looking up at stars, you have to look through all that air to see them. Now if you’ve ever looked into a pool or lake, you’ll know the things at the bottom look more distorted and less clear than if there was no water there at all. The less water you look through, the clearer the view gets. The atmosphere does the same thing when looking at the stars the less we look through, the clearer our view gets. Generally speaking, the higher the elevation, the better the seeing. By putting our telescopes high up on mountains, we look through less atmosphere, and get clearer observations.

Alright… So far we’ve narrowed our choices down to locations that are far away from big cities, and that are at high elevations for clearer observations. But dark skies and high altitude won’t make for good observations if it’s raining outside. So we need to further narrow our list down to places with good weather. More specifically, places with good weather on average. No matter where we are on Earth, there will be some cloudy nights we want to be somewhere where there will be as few cloudy nights as possible. Luckily, we’ve got decades of weather records for just about every place on Earth, so we have a very good idea of what the average weather is, and how many clear nights per year there should be for a location.

The last really important thing to consider is…the stars. The telescopes we’re building are going to be used by astronomers all around the world for years and years, researching everything from quasars and active galactic nuclei to exoplanets and variable stars. These different things are scattered all around in different parts of the sky, and when we build our big telescope, we don’t really know who is going to be observing with it, what they’ll observe, and when they’ll be observing it. So our best bet is to make sure our telescope has a chance of seeing every part of the sky, at some point over the course of a year. Wouldn’t it be horrible if, ten years after our biggest, best telescope was built, a really interesting and rare event like a supernova occurs in the southern sky, but our telescope is near the North Pole, and so it can’t ever look at it? Well, it would be horrible! And that’s why we typically have one last constraint on telescope location: we want it to be near the equator. A telescope placed at the equator is able to see over three quarters of the objects in the sky on any given night. On the north or south poles on the other hand, the same telescope would only ever see half of the objects in the entire sky, ever.

So we have four things that limit our choices for telescope location. We have to be far from cities, at a location that has a high altitude and good weather most of the time, and that’s close to or on the equator. What’s the final answer? Even with these restrictions, there are still a few places that are good enough to be home to 8 or 10 meter wide telescopes worth hundreds of millions of dollars. Mauna Kea, a dormant volcano in Hawaii, the foothills of the Andes mountains in Chile, the island of La Palma in the Canary Islands all have large observatories housing many of the world’s largest telescopes. They are all within 30 degrees of latitude of the equator, above 2500 meters altitude, and far away from city lights. Well over 70% of nights are clear enough to make observations, and depending on the season, there can be stretches of clear nights that span weeks.

Now these are just the best places in terms of these four limiting, albeit important, factors. There are other large telescopes around the world that trade off some of these advantages for other things. Some telescopes are located closer to cities, or in the countries that are funding them. There may be more light pollution or further from the equator, but they aren’t as remote. Some telescopes have been built near the North and South poles. They’re able to see less stars over a year, but the stars they do see can be observed for hours on end during the long, deep, polar nights during local winter.

It should also be noted that these locations are the best places on Earth to put a telescope. That doesn’t mean they’re the best places ever. You can get darker skies, better weather, look through less air, and see all the stars in the sky in other locations: Namely, in space. There are observatories like Hubble and Spitzer that orbit up in space, where none of these problems exist. However, new problems pop up, like space radiation, orbiting, and extreme remoteness, which makes them extremely expensive to design them, launch them, operate them, and heaven forbid, fix them.

So in the end, there’s no single place that’s the best location for our best telescopes. If there was, all of our telescopes would be there. This I think is a good thing. It allows people all over the world to be a part of the discoveries and excitement the telescopes in their home regions bring, it keeps all of our telescope eggs out of the proverbial basket, and creates opportunities for cooperative projects across the globe, adding some humanity to the seemingly serious and scientific task of observing the cosmos.

That brings me to the end of the podcast. I hope you learned something, and thanks for listening. Until next time, this is Robert Berthiaume wishing you all clear skies and good times.

Why are many observatories located on mountaintops?

Almost all of the world's finest ground-based observatories are located on mountains, for a variety of reasons. First and foremost, starlight appears less distorted in the thin atmosphere on mountaintops. (Space-based telescopes such as Hubble and Spitzer Space Telescope circumvent the disturbing effects of the atmosphere by flying above it.)

At high altitudes, there is less atmosphere to absorb infrared energy, which reveals details about some of the coldest objects in the universe, such as clouds of gas and dust and the disks of dust that give birth to planets.

Mountaintops also have unobstructed views of the horizon in all directions. Lastly, most cities and towns -- with their accompanying light pollution -- are situated in valleys and plains, so remote mountaintops are among the last places on Earth to find the dark skies so sought after by astronomers.