Astronomy

Why is the sunset at different times at the same longitude at equinox?

Why is the sunset at different times at the same longitude at equinox?


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I happen to live in two places that are literally at the same longitude but several thousand kilometers apart from each other (~47°N and ~68°N). It's just a few days until equinox - and I assumed that the sun would set at the very same time in both places. Equinox is supposed to be at September 22, 13:31 UTC. Using suncalc.org I calculated sunset for the northern location at 19:00h while the sun is supposed to set at 18:55 at the southern location.

Can someone please explain why this is?

I can't think of any effects due to refraction of the light as the angle is the same. The only idea I have that it might be due to the definition of sunset. If it is not calculated using the center of the sun, it might be off as sunsets take much longer in polar regions. Still, I'd be surprised if it was 5 minutes.

Also, I do understand that equinox is at 13:31 UTC which does not necessarily align with the sunset (in fact sunset is 3.5h after equinox). But to make things even more strange, even the next day the sun sets later in the north than it does in the south - I'd expect it the other way round. It is actually another day later, September 24, that the sun will set at exactly the same time in both places - (more than) two days after equinox.

PS: Not an astronomer myself, I'm just curious - please bear with me…


The only idea I have that it might be due to the definition of sunset.

The instance of sunrise occurs when the first bit of the Sun becomes visible at the horizon, while the instance of sunset occurs when the last bit of the Sun disappears below the horizon. This means the actual position of the center of the Sun is about 50 arc minutes below the horizon at sunrise / sunset.

At sunrise and sunset on the days of the equinoxes, the angle between the Sun's path and the horizon is roughly equal to 90° minus the absolute value of an observer's latitude. The Sun's path is much more oblique at your more northern location.

It takes the Sun about 200 seconds (3.333 minutes) to traverse those 50 arc minutes at the equator on the equinoxes. At some latitude $lambda$, it takes about $200 sec(lambda)$ seconds for the Sun to go from 50 arc minutes below the horizon to the horizon on the days of the equinoxes. That's 4.89 minutes at 47° latitude and 8.90 minutes at 68° latitude, a difference of four minutes.

The remaining minute could easily be due to rounding. Web sites typically publish sunrise and sunset times rounded to the minute because the difference between actual and predicted times varies by over a minute due to due to variations in the atmospheric state.


Why Isn't the Year's Earliest Sunset on the Winter Solstice?

The winter solstice occurs around December 21 in the Northern Hemisphere and June 21 in the Southern Hemisphere.

Apparent solar time is also called sundial time.

Winter solstice is the shortest day of the year in terms of daylight, but it does not have the latest sunrise nor the earliest sunset of the year.

This is because of a discrepancy between our modern-day timekeeping methods and how time is measured using the Sun known as the equation of time.


Why is the sunset at different times at the same longitude at equinox? - Astronomy

The shortest day of the year is the day of the winter solstice, which in 2020 is December 20 or 21 depending on time zone. It seems reasonable that the latest sunrise and earliest sunset would both occur on the shortest day. But it's not so the earliest sunset is a couple of weeks earlier and the latest sunrise is a couple of weeks later. [Note 1] (The notes contain additional explanation that can be skipped on first reading.)

What explains this peculiarity? Why don't the earliest sunset and latest sunrise both fall on the shortest day?

The time of day when the sun reaches its highest point in the sky is called solar noon. The length of time from one solar noon to the next is called the solar day. That is, one solar day is the time it takes for the sun to return to its highest point in the sky.

The length of the solar day varies during the year: Near the winter and summer solstices the solar day is more than 24 hours long, and near the spring and fall equinoxes it's less than 24 hours long. (Why so? We'll see shortly.) Therefore: near the solstices, solar noon occurs at a slightly later clock time each day because the solar day is more than 24 hours and the clock day is always exactly 24 hours.

Next: Since solar noon is a little later each day, sunset is also a little later each day. (This is true because the time from solar noon to sunset doesn't change very much near the winter solstice [Note 2].) But if sunset is a little later each day, that means the earliest sunset has already happened! By the same reasoning, later solar noons at the solstice imply later sunrises, hence sunrise is getting later and the latest sunrise is yet to occur. [Notes 3, 4]

So now we see why a longer-than-average solar day causes both earliest sunset and latest sunrise to not fall on the solstice. The next step is to understand why the length of the solar day varies, and in particular why it is longer at the solstices.

There are two factors that change the length of the solar day. The first is that the earth's axis is tilted with respect to its orbit around the sun, and the second is that the earth's orbit is not a circle but an ellipse. The first of these factors, called the obliquity of the axis, has the larger effect and is the only one we examine here [Note 5]. So let's study the length of the solar day assuming that the tilted earth orbits the sun in a perfect circle.

At any instant, there is exactly one point on the earth's surface where the sun is directly overhead. To find it, draw a line from the center of the sun to the center of the earth and stand on the point where the line touches the earth's surface. At that point, and no other, the sun is exactly overhead. It is solar noon at that point and also everywhere else at the same longitude.

If the earth were motionless with respect to the sun, the sun-directly-overhead point would always be in the same spot. But the point moves, both because of the rotation of the earth on its axis and because of the revolution of the earth around the sun. When the point moves once around the earth, one solar day has passed. When we say "once around the earth" we care only about the east-west motion of the point&mdashsolar noon recurs when the point traverses 360 degrees of longitude. The north-south motion of the point doesn't matter to us since it doesn't count in determining whether solar noon has arrived.

First let's examine the effect of the earth's rotation. Imagine an untilted earth not revolving around the sun, just rotating, and it's obvious that the sun-directly-overhead point moves along the equator, once around per day. Now mentally tilt the earth's axis and you'll see that the point follows some other parallel of latitude, still once around per day. [Note 6] Since the point moves along a parallel of latitude, it moves in a purely east-west direction, in fact due west. If we measure speed in degrees of longitude per hour (not in miles per hour!) we realize that the speed of the point is constant, no matter what latitude it's at it goes once around, 360 degrees, each day.

The bottom line is that the rotation of the earth causes the sun-directly-overhead point to move directly west, crossing lines of longitude at a constant rate. If this were the only factor to consider, the length of the solar day would be constant regardless of any tilt.

Now we have to add the effect of the earth's revolution around the sun. Again, start by imagining the earth with untilted axis, this time not rotating but just revolving around the sun. You'll see the sun-directly-overhead point moving once around the earth each year. And (take my word for this) the point moves eastward, so its motion is contrary to the motion from the rotation&mdashwhen added in, this motion makes each solar day a little longer than it would be from the rotation alone. (But just a very little, since the motion from the revolution is so much slower.) If the earth were not tilted, the motion due to revolution would be due east at constant rate, and would lengthen each day equally throughout the year.

But the earth is tilted! So the earth's revolution around the sun doesn't move the sun-directly-overhead point along the equator, but rather around a great circle that's tilted with respect to the equator. Here's the path that the sun-directly-overhead point would follow if only revolution around the sun was a factor (and also the constant-latitude path that the sun-directly-overhead point would follow if we only take into account the earth's rotation):

Now the crux of the matter: As the sun-directly-overhead point moves around this great-circle path, it is not moving directly east. It moves generally east, but sometimes it's travelling a little northeast and sometimes a little southeast. It moves due east only at its most northerly and southerly extent, which happens at the solstices.

So even though the overall speed of the point is constant, the eastward component of the speed is not constant, and that's what we care about: it's fastest when the point is moving due east (at the solstices), and is smaller when the point is moving north or south as well as east. The eastward speed is slowest when the point has the largest northerly or southerly motion, that is, at the equinoxes, when the point crosses the equator. [Note 7]

Hence this once-around-per-year motion of the point, which makes each day a little longer, has a different effect at different times of the year. At the solstices the motion is due east, so its eastward motion is fastest and lengthens the solar day more. That is, at the solstices, the solar day is longer than its average length. At the equinoxes, the point is moving northeast or southeast as much as it ever does, so the eastward component of its speed is at its slowest and has the least effect at making the day longer. That is, at the equinoxes, the solar day is a little shorter than average. And we're done.

One last comment: If you take a picture of the sun each day when your clock says noon (not at local solar noon) the sun is not always in the same place in the sky. It moves east and west because of the variation in the length of the solar day, and it moves north and south with the change of the seasons. The combination of these motions traces out a figure-eight shape called the analemma which you can see pictured on some globes.

Notes:

[1] The actual dates of earliest sunset and latest sunrise depend on latitude&mdashnear the equator, the earliest sunset occurs in November! Solstices and equinoxes happen at the same instant worldwide. back

[2] You might object to this: "The time between solar noon and sunset isn't constant!" I hear you cry. "It gets shorter in December and longer in July, making more or less daylight!" Yes it does, but that change happens very slowly near the solstices and can be ignored.

Think of it this way: There are two factors that change the time of sunset. The first is the change in the number of hours of daylight&mdashwe get fewer hours of daylight as we move towards December, which is reflected in earlier sunsets. The second factor is the difference between solar time and clock time, which we're explaining in this website (see Note 4). The first factor is the dominating factor through most of the year. Near the summer and winter solstices, though, the amount of daylight in the day is essentially constant, changing only a tiny amount from day to day, and the second factor comes into play. back

[3] We can apply the same reasoning to the summer solstice to conclude that the latest sunset must follow the summer solstice, and the earliest sunrise must precede the summer solstice. Just remember that at either solstice, both sunrise and sunset are getting later and you can always tell where the earliest/latest sunrise/sunset occur. back

[4] Here's another way to look at it: We don't tell time using the solar day, because we want all days to have exactly the same length. So we use clocks that run at a constant rate independent of the sun, ticking off exactly 24 hours each day. These clocks average out the variations in the solar day, making all days the same length, and so don't agree with the solar day. But when we ask about "earliest" sunset, of course we mean earliest according to the constantly-running clocks! The difference between clock time and true solar time creates the phenomenon we're investigating&mdashif we used only sundials to tell time, the earliest sunset and latest sunrise would coincide with the winter solstice. back

[5] The second factor that changes the length of the solar day is called the eccentricity of the earth's orbit. Not only does it have smaller effect than the obliquity, it works the other way in summer&mdashby itself, it would make the solar day shorter than 24 hours at the summer solstice. At the winter solstice, the obliquity and eccentricity work together to lengthen the solar day at the summer solstice, they oppose each other. Since the effect of the obliquity is greater, the solar day is still longer at the summer solstice. But because the total effect is less, there are a couple of weeks between the earliest sunset and the winter solstice, but only several days between the latest sunset and the summer solstice. Go here to see the individual contribution of each factor to the length of the solar day. (The equation of time, the thing being graphed, is just the difference between solar noon and clock noon. Note that it's the slope of the equation of time, not its value, that's important to this discussion.)

By the way, it's much easier to understand why the eccentricity changes the length of the solar day. You can find an explanation at any number of websites where the eccentricity is incorrectly trotted forward as the sole reason that the earliest sunset isn't the same day as the solstice! back

[6] It's too bad that I don't have more visuals on this site a picture is worth a thousand words and all that. If you'd like to help by creating graphics or animations to improve this page's explanations, winning undying honor and fame, please contact me. back

[7] The point doesn't move around the tilted circle at a truly constant speed, because the earth's orbit is not a perfect circle. The point moves slightly faster near perihelion (January) and slightly slower near aphelion (July). But the effect of this non-constant speed is less than the effect of the fact that the easterly speed varies depending on whether the point is going due east or northeast. In particular, the easterly component of the motion is at a near-maximum in July, because the fact that it is moving due east is more important than the fact that it's going a bit slower than usual. back

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Last modified 12/16/2019
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Happy September equinox! So what exactly does that mean, anyway?

This morning, at 07:50 UTC (03:50 Eastern US time), the center of the Sun crossed the celestial equator in the sky, marking the exact moment of the September equinox * .

This means several things. On this date, the Sun rises due east and sets due west. Some people like to think it's the start of the fall season (spring in the south), though I disagree. It's also commonly thought to be the day when we get 12 hours of day and 12 hours of night, but that turns out not to be the case due to some technical details.

One aspect of it that most people don't talk about much — but which ironically actually has an impact on your daily life — is that at this time, the length of daytime is changing the fastest (from here on out, for simplicity, I’ll just call this "day" as in "day and night"). You know that in summer the days are long, and in winter that's reversed. That means the length of the day changes, but the amount it changes every day isn't constant.

The longest day is on the June solstice (though, weirdly, that's not the date of the earliest sunrise and latest sunset due to Earth's orbit being an ellipse and its axis being tilted). On the next calendar day the length of daylight is slightly less, and even less the next day, and so on until the December solstice, when the Sun is up for the shortest length of time all year. Then that trend reverses.

But if you measure how long each day is (that is, how long the Sun is up), that number changes very little at the solstices, but it changes very rapidly at the equinoctes!

A diagram showing the Earth’s tilt over the course of the year. The axis stays pointed in the same direction in the sky, but dips toward the Sun in the summer and away in the winter. Credit: Colivine / wikipedia

An example should help. I looked up the time of sunset for Boulder, CO (using the SkySafari app) for the week centered on today's equinox (the time of sunset changes with latitude and longitude, and I live near Boulder, so there you go). Here they are:

Fri Sep 20 19:01:09
Sat Sep 21 18:59:29
Sun Sep 22 18:57:49
Mon Sep 23 18:56:09
Tue Sep 24 18:54:30

As you can see, the Sun is setting earlier every day that's been true since June. But note how much earlier it sets: by about 1m 40s every day.

Now let's look at the times of sunset around the December solstice coming up on December 22:

Fri Dec 20 16:37:14
Sat Dec 21 16:37:42
Sun Dec 22 16:38:13
Mon Dec 23 16:38:46
Tue Dec 24 16:39:20

The Sun sets a little later every day, but look how slowly it changes, only by about 30 seconds every day. That’s much less than it's changing right now, in September.

See? The length of daylight is changing fastest at the equinox, and slowest at the solstice.

All of this is analogous to how high the Sun is off the horizon at noon, too. In the winter the Sun is low in the sky at noon, and in the summer it's much higher. The amount it changes every day is fastest at the equinoctes, and slowest at the solstices! You can check this for yourself: Go to the timeanddate.com site and enter your location. Again, I use Boulder. Then go to September of this year — here's the page for Boulder. The last column is the time for solar noon, when the Sun is highest in the sky. The number in parentheses after it is the height of the Sun off the horizon in degrees (so today on the September equinox for me it’s 49.8°). That number changes by very roughly 0.3–0.4° per day. But if I look at December around the solstice it barely changes at all!

So the question is, why is this happening this way? It's because the Earth is tilted: The axis of its rotation is tipped by 23.5° from being vertical relative to the plane of Earth's orbit. You've seen this a zillion times globes have the Earth titled this way, for example. As the Earth orbits the Sun the axis stays fixed in space, with the North Pole pointing very close in the sky to the star Polaris. The June solstice is when the North Pole is tipped toward the Sun, and the December solstice is when it's tipped away. The equinoctes are when the axis is pointed 90° away from the Sun (which, maddeningly, is not halfway in time between the solstices, because the Earth's orbit is an ellipse and it moves at different speeds around the Sun at different times of the year).

I know, the geometry can be confusing. But the upshot of all this is that when the Earth's northern axis is tipped toward the Sun, the Sun gets higher in the sky at noon. When it's tipped away six months later, the Sun is at its lowest point in the sky at noon. If you think about it, that difference should be twice the Earth's tilt, or about 47° (the sum of the angles between when the axis is pointed away from the Sun and when it's pointed toward it: 2 x 23.5°). If I go back to the timeanddate site and look at the Sun's altitude over the horizon at noon on the June solstice (on the 21st earlier this year), its height was 73.4°. On the December solstice it was 26.6°. Subtract them: 73.4 – 26.6 = 46.8°.

Four views of Earth from the DSCOVR satellite 1.5 million km from Earth toward the Sun — this is the view you’d have facing the Earth with the Sun at your back. From left to right: Sep 23, 2018, Dec. 21 2018, Mar. 20 2019, and Jun 21, 2019. Note how the Earth’s north axis tips away from the Sun from September to December, then starts to tip back through March, June, and September again. Credit: NASA/NOAA

[OK, I'm about to describe some math. If that fills you with terror, I get it, and you can safely skip it … but it does explain everything I've been talking about. Fairly warned be thee, says I.]

The way the math works here, the change in the Sun's height over the horizon changes as a trigonometric sine wave during the year, with an amplitude of the crest (which occurs on the June solstice) of 23.5° above average, and 23.5° below average for the trough (on the December solstice). The rate of change of a function is called its derivative, and the derivative of a sine wave is a cosine wave. When the sine is at its most extreme values (highest and lowest values: its crest and trough), the cosine is 0. So that means at the solstices, when the Sun is highest and lowest at noon, the change in its height every day is very low. When the sine is at 0 (the Sun is at the midpoint between max and min height, so the equinoctes) the cosine is at an extreme (either its max or min value), which means the Sun's height is changing the most rapidly day to day. See?

Representation of the height of the Sun over the horizon at noon over the year. The y-axis is arbitrary, just meant to represent the variation in height the x-axis is again representative (not literal) and goes from Sep to Sep. Different times of the year are marked. The height of the Sun goes as the trigonometric sine, and the rate of change in its height as the cosine. Credit: Wolfram Alpha/Phil Plait

It's the same with the time of sunset, too. Right now, the Sun is setting earlier every day, and the amount it sets earlier is at its most rapid.

There's one more thing (because of course there is). On the equinox the Sun sets due west. If you go back to timeanddate.com and look at the time of sunset for today (the second column), the number in the parentheses is the azimuth, the number of degrees from north clockwise around the horizon where the Sun sets. North is 0°, east is 90°, south is 180°, and west is 270°. And see? The number listed for today is in fact 270°, due west.

If you poke around you'll also see it sets at an azimuth of 240° at the December solstice (so, 30° south of west), and at 302° (32° north of west) at the June solstice (again, I believe it's the Earth's elliptical orbit throwing those numbers off from being symmetric around 270). So in the summer it sets north of west, then moves south every day, little by little at first, then gaining speed, setting due west on the September equinox, then starting to slow after that while still heading south. At the December solstice it gradually slows to a stop, then turns around and starts heading north again.

And hey: The word solstice comes from the Latin solstitium, which literally means "the Sun stands still." Hopefully now that word makes sense to you!

But this brings up a final thought. We like to think of the Universe as orderly, neat, like gears turning in a great machine. And in a way it does! The Earth spins, it goes around the Sun, we have seasons and days. But those gears aren't exactly round, and don't exactly fit together at a 90° angle, so the details of how all the parts mesh together gets complicated fast.

But it affects us, every day. Many times the change is slow, but other times it's fast. As I said earlier, one of the biggest impacts of this is that the Sun sets noticeably earlier every day right now. I live a little east of the Rocky Mountains, which provide a stable foreground for sunsets, and this time of year you can see the Sun setting behind different mountains every night! It's really obvious.

Moreover, we have to put the goats to bed in their shed at sunset (Colorado has coyotes, and goats are tasty), and that time changes with the seasons. Right now it's right around the time we have dinner, so we always wind up having to change our schedule this time of year for when we eat, when we take care of the animals, and other chores.

Even with nearly a fifth of the 21st century under our belts, we still are beholden to the Sun, the Earth, and the angles they make between them. It's cool to be able to understand them.


How Latitude Affects the Time of Sunset and Sunrise

If you live between the Tropic of Cancer and the Tropic of Capricorn, the amount of daylight you get each day doesn’t vary much. If you live near the equator, it’s pretty much thirteen-hour days and eleven-hour nights year round, with sunrise around 7:30 am and sunset around 8:30 pm. (You get a bonus hour of daylight because the sun’s rays are refracted above the horizon for a short time before the sun rises and after the sun sets.) However, if you live farther north or south, you’ll find that your days are a lot longer in summer and a lot shorter in winter. That’s because latitude affects the time of sunset and sunrise.

Earth is tilted on its axis, by about 23 degrees or so. That’s why the parts of the Earth that are nearest the sun aren’t always the same.

The tilt always stays the same direction, so the North Pole always points towards Polaris, the North Star. That’s why Polaris is always the North Star. (Well, except for precession, but that takes thousands of years and isn’t important right now.)

At the same time, two other things are happening.

Earth’s spinning on its axis. That’s what causes day and night. Each part of the Earth experiences day when it’s pointed towards the Sun, and night when it’s pointed away from the Sun. It takes about twenty-four hours to make one complete revolution.

Sunrise happens when a place on the Earth reaches the sunlight as the Earth revolves. Sunset happens when a place on the Earth leaves the sunlight and enters the shadow cast by the Earth itself.

Earth’s also going around the Sun in its orbit. It takes about one year to make a complete orbit. The orbit means that the Earth’s axis isn’t always going to be pointed the same way relative to the Sun. Sometimes the daylight side of the northern hemisphere is closer to the Sun, and sometimes the daylight side of the southern hemisphere is closer to the Sun.

The combination of all these things means that at every time of year, some parts of the Earth get earlier sunrises and later sunsets than other parts. How much more daylight they see depends on their latitude.

June in the northern hemisphere

In June, the North Pole is at its closest to the Sun, and it’s pointing inwards, towards the Sun at an angle. When that happens, the whole northern hemisphere reaches the sunlight earlier and leaves it later as the Earth spins in space. When you’re looking at it from the surface of the Earth, the Sun rises earlier, and sets later.

That’s why every part of the northern hemisphere gets longer days and shorter nights, all summer long. The angle of the Earth’s axis means that sunrise is earlier as you go farther north, and sunset’s later. The longest day of the year is called the summer solstice. It’s usually around June 21.

It’s pretty extreme too. By the time you’re north of 45, you’ll get sunrises that are as early as 5:30 am, and sunsets around 9:30 pm or so. Once you get north of 60, the daylight’s nearly round the clock.

When you go farther north than that, things start to get really strange. By the time you reach the Arctic Circle, the days are around the clock, but it’s usually just for the summer solstice. If you go farther north, you’ll get more and more days that are round the clock sunlight in summer. At the North Pole, you’ll get six solid months of daylight!

June in the southern hemisphere

In the southern hemisphere, the opposite’s happening. The South Pole’s at its farthest from the Sun, so it’s winter down there. It gets stuck with six months of darkness, three months on each side of the winter solstice. Sunrise won’t happen until September.

That’s why the whole southern hemisphere reaches the sunlight later and leaves it earlier as the Earth spins in space. The angle of the Earth’s axis means that sunrise is later in the southern hemisphere in June, and sunset’s earlier. The shortest day of the year is called the winter solstice.

Polar nights are long, but they get shorter as you go farther north. You don’t get a ray of daylight on the winter solstice until you get north of the Antarctic Circle.

When you’re in the southern hemisphere in June, the Sun rises earlier as you go farther north. The Sun also sets later as you go farther north, right up until you reach the equator.

As you get closer to the equator, the winter days get longer and longer. Actually, it feels less and less like winter. By the time you reach the equator, the days are just about the same length as the nights. It varies a bit with the seasons, but not so you’d notice unless you’re paying really close attention.

In December, the South Pole’s at its closest to the Sun, so the southern hemisphere’s experiencing summer. At the same time, the North Pole’s farthest away, so it’s experiencing winter. It’s basically the exact opposite of what was happening in June.

The turnaround times between the northern and southern hemisphere are called the equinoxes, because that’s the time of year when the duration of days and nights are the closest to being the same. During these times, the North Pole and South Pole are about the same distance away from the Sun.

One equinox is around March 21. In the northern hemisphere, it’s called the spring equinox. The other equinox falls is around September 21. In the northern hemisphere, that’s the fall equinox.


Why does sun rise and set at different times in different places

Axial tilt! When the Earth rotates (spins), it does not stand up on its poles (with respect to the Sun). Instead it's rotating on an angle, about 23.4°. If it wasn't tilted, the Sun would set at the same time and place every day. However, as the E.. The Variation in Sunrise and Sunset Times Because of the Earth's tilton its axis, the path of the Sun across the sky varies, and therefore, the rising and setting time changes. At different locations on Earth, the rising and setting times vary because the portion of the celestial spher How different they are. If we consider three towns say Chennai, Bengaluru and Mangalore - the sun rise and sun set timings are different. This can be simply explained by the fact that earth rotates. The earth may be rectangular, round or oblate - this answer still holds good The sun appears to rise on the eastern horizon and sets on the western horizon. How much does the location of the sun rising and setting change throughout the year and depending upon where your viewpoint is, i.e., true East, true West, etc Things would be different if: (1) Earth orbited the Sun in a perfect circle and (2) Earth's axis was perpendicular to the plane of its orbit (straight up and down). If that were the case, the Sun would rise and set at the same times every day. It would also take the same path across the sky every day of the year

As a result, at some points in the orbit of Earth, the north pole is tilted towards the Sun, and at other points it is tilted away from the Sun. In the first case, the Sun is north of the equator, and in the second case the Sun is south of the equator , the higher your location is, the earlier the Sun will rise, and the later it will set, compared to when it would for the same location if it were at sea level

Areas in red see the sun rise and set late in the day areas in green see it early. Obviously, the regions which are white sit centrally in the time zone in which they're located—the best. . It doesn't rise and set. But it appears to rise and set because of the Earth's rotation on its axis. It makes one complete turn every 24 hours

. Web sites typically publish sunrise and sunset times rounded to the minute because the difference between actual and predicted times varies by over a minute due to due to variations in the atmospheric state The topic - does the sun rise or set - is a question most of my students could answer. However, not a single one could give a reasoning as to why they know other than they were told that is was true. This gave all of my students concrete understanding of how the Earth moves and an understanding of how its movements cause night and day

Why does the Sun set at different times and places? - Quor

  • The sun rises and sets in different places because the axis of rotation of the Earth is tilted with respect to the plane of the ecliptic. Since the Earth is rotating about its axis at the same time..
  • As Earth rotates, different parts of Earth receive sunlight or darkness, giving us day and night. As your location on Earth rotates into sunlight, you see the sun rise. When your location rotates out of sunlight, you see the sun set. Imagine if the entire Earth had a single time zone
  • Answer: The Sun, the Moon, the planets, and the stars all rise in the east and set in the west. And that's because Earth spins -- toward the east. For a moment, let us ignore Earth's orbit around the Sun (as well as the Sun's and solar system's revolution around the center of the Galaxy, and even the Galaxy's journey through the universe)
  • When you're looking at it from the surface of the Earth, the Sun rises earlier, and sets later. That's why every part of the northern hemisphere gets longer days and shorter nights, all summer long. The angle of the Earth's axis means that sunrise is earlier as you go farther north, and sunset's later

Variation in Sunrise and Sunset Time

  • If the axis of earth does not have a tilt as it is now and if it were to be perpendicular to the plane of revolution of the earth around the sun,the day time and night time will be equal in all the places throughout the year.In that case the sun rise time and sun set time will also be the same thoughout the year in all places of the earth
  • The sun appears to move along with the celestial sphere on any given day, but follows different circles at different times of the year: most northerly at the June solstice and most southerly at the December solstice. At the equinoxes, the sun's path follows the celestial equator
  • The first major contributor to the Sun's apparent motion is the fact that Earth orbits the Sun while tilted on its axis. The Earth's axial tilt of approximately 23.5° ensures that observers at..
  • g of the sunrise is affected by the altitude, time zone, longitude, and latitude of the viewer
  • So, where does the Sun actually rise and set? Though it does rise from an easterly direction, it's also slightly more north or south in the sky day by day. That means we actually see the sunrises and sunsets in a slightly different place along the horizon every single day
  • When does the Sun rise and set? On the other days of the year, the Sun rises either north or south of due east. It will also set either north or south of due west. The rising points as well as the setting points change slightly every day. This is one of the reasons why the Sun rises on different times each day in a particular place
  • Earth's Orbit Around the Sun: With an average orbital velocity of 107,200 km/h (66,600 mph), the Earth takes approximately 365.256 days - aka. a sidereal year - to complete a single orbit of.

The sun rises and sets at different time in different

  • utes of daylight than Rafsanjan does, and the north pole has 24 more hours of daylight than the south pole does
  • 1) the time of year 2) your latitude The sun's movement along your horizon - at sunrise or sunset - is most perceptible around the equinoxes and least perceptible around the solstices
  • And it gets to its highest point in the sky at a different time each day. Advertisement. We see the Sun rise in the east and set in the west once every 24 hours or so. But that east-to-west.

How does the location of sunrise and sunset change

  • This time is somewhat different from the more specific definition which is called the geometric rise or set. The geometric rise or set of a celestial body is when the center of the object, such as a star, passes the horizon and there is no atmospheric refraction. Please see the next few questions
  • The angular difference between the direction of sunrise and due east, and the direction of sunset and due west is called the sun's amplitude. The sun's maximum amplitude is seen on each June and December solstice. The exact maximum amplitude depends on your latitude
  • Sunrise, sunset and moon phases in over 1030 locations all across United States today

Why Does the Sun Rise and Set at Different Times Each Day

  1. Answer to Why does the sun rise and set at different times around the world? Explain. Skip Navigation. Chegg home. Books. Study. Textbook Solutions Expert Q&A Study Pack Practice Learn. Question: Why Does The Sun Rise And Set At Different Times Around The World? Explain. This problem has been solved! See the answer
  2. utes.
  3. But why does the Sun rise in the east and set in the west? In fact, you will always see the Sun rising in the east because the Earth rotates on its axis from west to east. In other words, it spins toward the east, making it look like the Sun is moving west
  4. Daylight hours: Understanding sunrise & sunset times. Daylight hours represent the amount of time from sunrise to sunset - not to be confused with sunshine hours, which shows how much bright sunshine you can expect at your chosen destination in every month of the year.. Understanding how daylight hours are measured, plus where, when and why places see more or less daylight throughout the year.
  5. Does the sun set at different times in different places in the same timezone? I noticed that according to the timezone maps, Chicago and Cancun are in the same - for lack of a better term - vertical zone. Both cities also have the same time. But what I wonder is, in the summer the sun takes longer to set in Chicago - maybe around 8pm

Why does the location of sunrise change? (Intermediate

  • The Sun does rise and set at a different time each day, but the daily difference is small. Since the December solstice, the days have been getting longer in the northern hemisphere and shorter in the southern hemisphere. After the June solstice, this will reverse. The moon moves from West to East across the sky
  • Buy AumSum Merchandise: http://bit.ly/3srNDiGWebsite: https://www.aumsum.comOur earth rotates on its own axis. Due to this rotation, different parts of the e..
  • Sunsets on other planets appear different because of differences in the distance of the planet from the Sun and non-existent or differing atmospheric compositions
  • Today in precalculus, we looked at some data that follow a sinusoidal pattern and calculated a regression function to model it. Here's how we did it: The hours of daylight over a year increase, then decrease in a regular, periodic fashion - just the kind of data that result in a nice sine curve. Th
  • utes later each day in our skies, which may come as a surprisingly large daily change, particularly if you're used to the much more gradual changes of.

Tonight at sunset I went to one of my local spots to take some photographs and noticed that the sun was not setting in the same place as last year on the exact same date. ( I checked a sunset photograph from the 2nd June 2010) .Taking a clock face to empahasise what I mean, The sun set at 12 last year, yet tonight it set at the 3.00 o,clock point The earth circles the sun in an elliptical orbit whose speed varies over the course of a year. As a result, the sun not only appears to move north and south in the sky, but the rate of its west-to-east progression appears to vary with the seasons: if you were to record the sun's position in the sky once every (fixed-length) synodic day it would appear to move in a lopsided figure-8 called an. The times of Sun rise and set for other places in New Zealand can mostly be estimated within about 5 minutes from the times in the tables. Note that for places with the same latitude, a difference of 1° in longitude makes a difference of 4 minutes. Times are earlier for places to the east and later for places to the west Because of Earth's tilt, the sun doesn't rise or set along a vertical line, but at an angle. When viewed from all latitudes north of the Tropic of Cancer (23.5 degrees north latitude), the sun..

why does the sun rise in the east and set in the est from earth's perspective? The earth's rotation. Does the moon emit light of its own? no. The rotation of the sun causes us to see different stars at different times of the year. why determines the different seasons on earth Sunrise and Sunset are defined as the exact moment the upper edge of the Sun's disk touches the eastern and the western horizon, respectively. The time it takes for the Sun to fully set, which can be several minutes, makes the day just a bit longer than the night on the equinoxes. Approx. date of Equal Day & Nigh And that's why this phenomenon is called the Midnight Sun. Strand took that photo from just inside the Arctic Circle (24° south of the north pole), in Gällivare, Sweden, at just about. The Sun never sets or rises, it stays the same distance over the Earth throughout it's daily/annual journeys around. The appearance of rising and setting is all based on the law of perspective on plane surfaces. The Sun and Moon spotlights are perpetually hovering over and parallel to the surface of the Earth Q: Why is the rise or set time off by 1 hour? I found a sunrise, sunset or moon time on another web site, the TV or the newspaper and it is different from the one here by an hour. What is the difference and which one is correct? A: It is probably because one of the times is not being adjusted to daylight saving time (DST) properly

the moon and the time sequence that you determined. 6. Explain that the Moon rises and sets at different times depending on what phase it is in, meaning where the Moon is located relative to the Sun and Earth. In fact, for some phases the Moon can be seen in the day time! Each unique phase rises/sets at a different time and Hence this once-around-per-year motion of the point, which makes each day a little longer, has a different effect at different times of the year. At the solstices the motion is due east, so its eastward motion is fastest and lengthens the solar day more. That is, at the solstices, the solar day is longer than its average length Every day, the Earth spins once around its axis, making sunrises and sunsets a daily feature of life on the planet. It has done so since it formed 4.6 billion years ago, and it will continue to do. The Sun City Page provides Sun times, angles, and more for any date. You can access it by clicking on the Sunrise & Sunset tab. Click on a row in the table to see the Today's Sun Position graph for the selected date. The same applies to the Moon City Page, where you can find detailed Moon info for any date. Click on the Moonrise & Moonset tab.

Sunrise and Sunset Times around the World. America. New York San Francisco Denver Toronto Vancouver Hawaii Chicago Dallas Sao Paulo Mexico City Bogota Lima Santiago Beunos Aires Rio de Janeir April 2021 - Time, Illinois - Sunrise and sunset calendar. Sunrise and sunset times, civil twilight start and end times as well as solar noon, and day length for every day of April in Time. In Time, Illinois, the first day of April is 12 hours, 42 minutes long The Moon rises and sets every day, like the Sun. But the Sun always rises in the morning and sets in the evening the Moon does it at a different time every day. At New Moon, the Moon lies in the same direction as the Sun. But the Moon is orbiting around the Earth every day, it moves eastwards (further left from the Sun) by about 12 degrees.

Why does the sun rise in the east and set in the west. The truth, however, is that the sun does not rise in the east or set in the west. It is a visual illusion that we all experience. The earth has two different movements. It is continuously rotating around its own axis. To complete one rotation around its axis, the earth takes 24 hours As a result of earth's axial tilt, the sun does not set in the Arctic circle region during the summer solstice and at the North Pole, the Sun does not set for 6 months. Similarly, it does not set in the Antarctic circle region during the winter solstice and at the South Pole, it does not set for six months

Not All Sunrises are Created Equal - Farmers' Almana

On the Summer Solstice, which occurs on June 21, the Sun is at its highest path through the sky and the day is the longest. Because the day is so long the Sun does not rise exactly in the east, but rises to the north of east and sets to the north of west allowing it to be in the sky for a longer period of time Bing Places for Business is a Bing portal that enables local business owners add a listing for their business on Bing. Using Bing Places for Business, local business owners can verify their existing listing on Bing, edit or update the listing information, add photos, videos, services and other information that shows their business in the best possible way Even robots can't tear their eyes from a beautiful sunset. NASA's Mars Curiosity rover pointed its high resolution mast camera at the setting Sun to capture this 4-image sequence on April 15. The March 2021 equinox happens on March 20, 2021, at 09:37 Universal Time. That's early morning, March 20 at 4:37 a.m. Central Daylight Time for us in the central U.S. Translate to your time zone

Peter, this is easy to estimate using the website time and date.Enter your location and navigate to the 'Sunrise & Sunset' page. There you will find tabulated the 'daylength'.For your location - and as an example for anyone else to follow - the daylength on Jan 15 2020 was 8:15:12 [h:m:s] and on December 21 2019 daylength was 7:44:01 NASA's Viking 1 lander first showed humans what a sunset looked like on Mars in 1976. Several more Red Planet robots have since sent back a variety of views of Martian sunrises and sunsets. Some color-corrected, blue-hued images preview what human Mars explorers might one day see while relaxing after a hard day's work on the fourth planet

Re: Sunrise/sunset on the equator « Reply #7 on: August 19, 2008, 03:18:35 PM » If the sun rises in the east and sets in the west, then someone please explain why an observer on the equator on the day of the equinox must look north east to watch the sun rise and north west to watch the sun set on the FE A number of other variables play into the time difference. The Moon's orbital speed is not constant, so its motion relative to the stars can be up to 12 percent faster or slower than the average. 4.1 Question: It seems impractical to find the time for Asr based on object's length plus shadow at Zawaal time for Shafi'i, or twice the object's length plus shadow at Zawaal time for Hanafi. How, an individual is supposed to know what is the shadow at Zawaal time. It appears to me that both Shafi'i and Hanafi Fiqh are not practical for this Oxygen and Nitrogen (the main components of our atmosphere) scatter violet and blue light due to their small size. This is why the sky appears to be blue in the day time, especially at midday when the Sun is closest to us. During sunrise and sunset the distance that the light has to travel from the Sun to an observer is at its greatest Twilight is the period of time in between day and night, and is caused by refraction and the suns rays scattering from the atmosphere. What most people don't know is that there are three different phases of twilight, each with very distinct and unique features that open up different worlds of opportunities for your images

With watchOS 7, your Apple Watch can automatically change which face it shows, swapping you from an evening wear one, to a complications-laden work face, depending on the time of day — or where. Beginner's guide How to set up multiple time zone clocks on Windows 10 Windows 10 lets you view up to three different time zone clocks — here's how to set up and keep track of even more

You can change your Home Network four times in 12 months. YouTube TV however, will let you watch from multiple locations, however, the account has to be streamed on a TV device from your home Zip Code at least once every three months. AT&T TV NOW allows you to watch on two TV devices form different locations at the same time. However, AT&T TV. Some of those are set in Shakespeare's own time, some in Medieval Europe and some in ancient Europe. The Greek and Roman Empires feature in many of the history plays, with action taking place in North Africa (Lybia and Egypt) and what we now refer to as the Middle East (Lebanon, Syria & Turkey)

So calendars could be made, so people could plant their crops at the best time of the year. An important feature is that the moon always keeps the same face towards the earth. If different parts were visible at different times, the moon's brightness would depend on which part was pointing towards the earth At the same time, you can do the pointing activity in the second demonstration to notice how the stationary Sun seems to be at different places relative to the map-person. See the link below for a wrap around map. This activity is adapted from Eye on the Sky: lesson 5 of Our Star the Sun. See links below for th 1. People's different perceptions of places and regions are influenced by their life experiences. Therefore, the student is able to: A. Describe examples of how perceptions of places and regions are based on direct experiences (e.g., living in a place, travel) and indirect experiences (e.g., media, books, family, and friends), as exemplified by being able t You may be surprised to learn that, more often that not, the Moon rises in the east and sets in the west however, depending on the phase of the Moon and the time of the year, the rising might actually occur in the east-northeast or east-southeast, and the setting might take place in the west-northwest or west-southwest It seems that, at times, high places were set up in a spot that had been artificially elevated 2 Kings 16:4 seems to differentiate the high places from the hills. The Israelites, forever turning away from God, practiced Molech worship and built high places for Baal (Jeremiah 32:35)

How the Time of Sunrise and Sunset Varies Around the Wrol

  1. Obviously, the perception of this state would be different at various points around the world, and the sun would appear to be at its highest point at a different time of day in Europe than it would appear to be front and center in the United States. Setting time zones helps to accommodate this desire
  2. ates the whole hemisphere of the earth which is turned toward it, from pole to pole
  3. But inside the cylinder, matters are radically different. The time direction - the one-way direction - now corresponds to the radial direction, while the axis direction is just another unrestricted space direction. In a way, space and time have changed places! This has remarkable consequences for the way that objects move as time passes
  4. Sunset Symbolism in Different Cultures Many cultures and religions across the world respect and appreciate the sun — and associate its rising and setting with something much larger . In cultures the world over, the sun has long been a symbol of power, growth, and the cycle of life
  5. Earth rotates on its axis, leading to sun rise and sun set in different parts of the world. The part of the earth which receives sunlight, experience day whereas the part in the darkness experience night. In other words, different parts of the earth receive daylight at different times
  6. Without the sun shining during the day, we would be able to see the winter constellations during the daytime in the summer (and vice versa). Because the Earth changes position around the sun throughout the year, we get a different view of the stars in the Milky Way Galaxy during different times of the year

Oxygen and Nitrogen (the main components of our atmosphere) scatter violet and blue light due to their small size. This is why the sky appears to be blue in the day time, especially at midday when the Sun is closest to us. During sunrise and sunset the distance that the light has to travel from the Sun to an observer is at its greatest Supernatural does film at a many different places but for the most part they are all contained to Vancouver. Despite the fact that Jensen Ackles and Jared Padalecki are both Texas boys, they have to relocate all the way to the cold of Canada to film their show every year The probable explanation is that it is due to the rounding to the nearest minute in the calculation of sunrise and set times. If they were calculated to the nearest second then the curves calculated from them would be smoother

Blue light is scattered in all directions by the tiny molecules of air in Earth's atmosphere. Blue is scattered more than other colors because it travels as shorter, smaller waves. This is why we see a blue sky most of the time. Closer to the horizon, the sky fades to a lighter blue or white . However, solar noon would not change, since we define time of day based on it. #92endgroup$ - user10851 Sep 25 '12 at 8:0 Thanks to the ancient civilizations that defined and preserved the divisions of time, modern society still conceives of a day of 24 hours, an hour of 60 minutes and a minute of 60 seconds

Answer: Sunset occurs when the upper edge of the Sun - called the upper limb - sinks just under the horizon sunrise occurs when the upper limb rises just above the horizon. The same is true for the Moon Think of a clock which is set to run 25% faster than normal time: After 12 hours of normal time it has covered 15 hours, and after 24 hours of normal time it has covered 30 hours, which means that. Three consecutive storm systems over the Southern Ocean are set to produce a powerful and large swell in time for the start of the Margaret River Pro. 1d ago This mayor wants to permanently change time, but his first mission is shortening daylight savin Time of day - Your weight can fluctuate throughout the day. So for the most accurate tracking, you want to weigh at around the same time. You can weight with different scales or in different places, but track only the weight in the same settings to have a truly comparative view. June 12, 2013 6:27PM. 0

Dawn occurs before sunrise, before the top of the Sun reaches the horizon. Astronomical Dawn is the point at which it becomes possible to detect light in the sky, when the sun is 18° below the horizon. Nautical Dawn occurs at 12° below the horizon, when it becomes possible to see the horizon properly and distinguish some objects If you ask an American about the way their dates are formatted, you may get a response as defensive as 'my jumper is not on back to front, it's supposed to have the v at the back!'.. But let's. A day consists of both day time and night time. The period between the sun rise to the sun set is called the day time. The part of the earth that receives sunlight experiences the day time of the day while the part that does not receive sunlight experiences the night. Day and night changes based on the revolution of the earth on its axis The next meteor shower is the Eta Aquarids—which peak May 4-5!See details with best time to view, number per hour, point of origin, and associated comet in..

View sunrise and sunset times in any location and on any day Longest day and longest night. The longest day of the year in the Northern Hemisphere occurs at the Summer Solstice. On the same day, at the same time, in the Southern Hemisphere, the Winter Solstice brings with it the longest night of the year If any of those IP addresses are used by a scammer, or a computer thief, or a suicidal person contacting a help line, MaxMind's database places them at the same spot: 38.0000,-97.0000 . But because the moon is also doing a lap around the Earth, the moon is going to appear at different points in the sky at different times of the day and night. So sometimes the moon will be up during the day And why does the moon seem to look different - even from the same spot - over the course of a single night? EarthSky lunar calendars show the moon phase for every day this year. A few left Many people think of Alaska (and the entire Arctic region) as a place of cold, snow, and darkness. And for a portion of the year, that is true. On the winter solstice (Dec. 21), Anchorage experiences about 5 hours of daylight. Residents of Barrow say goodbye to the sun on Nov 18. They won't see the sun rise again until January 22

Why does the sun rise and set? - Journey Nort

  1. In the When calculating this workbook section, select the workbook you want, and then select the Set precision as displayed check box. Click OK. Going back to my absolute difference example, I set the number format to show four decimal places, and then I turn on Precision as displayed option. Since the display value is the actual value in the.
  2. Self-recognition of gender identity develops over time, much the same way a child's physical body does. Most children's asserted gender identity aligns with their assigned gender (sex). However, for some children, the match between their assigned gender and gender identity is not so clear
  3. The value of one pip is always different between currency pairs because of differences between the exchange rates of various currencies. A phenomenon does occur when the U.S. dollar is quoted as.
  4. Core values are what support the vision, shape the culture and reflect what a company values. They are the essence of the company's identity - the principles, beliefs or philosophy of values
  5. Why does my computer think I'm in a different city than where I actually live? I called my service provider and they didn't have an answer. Previously was on XP Professional, did fresh install of Windows 7, repartitioning HDD and thought this would fix the problem once all reloaded like a new pc

The sun - Why is the sunset at different times at the same

The time period right before night time can be defined as the twilight. Twilight starts when the sun goes beneath the horizon, meaning when the sun is setting. Some light is still visible during this time period even though it may look very dark when the sun is setting. Before it gets dark three different phases of this time period can be observed A time-lapse of the daylight cycle The daylight cycle is a 20-minute-long cycle between two main light settings. 1 Conversions 1.1 Minecraft time to real time 1.2 Real time to Minecraft time 2 24-hour Minecraft day 2.1 Daytime 2.2 Sunset/dusk 2.3 Nighttime 2.4 Sunrise/dawn 3 Clocks 4 Commands 4.1 Set time 4.2 Moon phases 5 Achievements 6 Video 7 History 8 Trivia 9 Notes 10 References In. Continued. Behind-the-ear (BTE) hearing aids sit in a hard plastic case behind your ear.A plastic ear mold fits inside the outer ear and directs sound to the ear. A different type, called a Mini. At the equator, you would get 1 minute extra sun at either end of the day per 1.5km of altitude, according to this page.. Using trigonometry, for every degree north or south you travel, the extra time the sun would stay above the horizon (per 1.5km altitude) would be (1/cos (latitude)) * 1 minute per 1.5km, giving the following values

Why does the Sun rise and set? - Mystery Scienc

Despite the fact that we live in an enormous universe with seven different continents, nearly 200 different countries, more than 7 billion people, thousands of languages, and hundreds of thousands of unique experiences, we stick to what we know. Then we wonder why we feel stuck, stale, and stagnant So, Why Isn't the Bible in Chronological Order? The books of the Bible are not listed in chronological order, as they are divided by different forms of literature. There are 66 books in the Bible that cover a time span of 1500 years the Old Testament consists of 39 books and the New Testament consists of 27 Historically, the Texas grid's independence has been violated a few times. Once was during World War II, when special provisions were made to link Texas to other grids, according to Cudahy

Why does the sun rise at different times in different

The amount of interest paid depends on the terms of the loan, worked out between the lender and the borrower. Interest represents the price you pay for taking out a loan - you still have to pay. SET — Sun. Moon — — Moon Why does the daily moonrise time vary by as much as 60 minutes, and as little as 30 minutes during the same month? Jim Wakefield, Bend, Oregon. Published: Monday. The phrase heavenly places or heavenly realms is used several times in the book of Ephesians (1:3, 20 2:6 3:10 6:12). This phrase is translated from the Greek word epouranios, meaning the sphere of spiritual activities. Heavenly realms can refer to both angelic and demonic activity.Ephesians 1:20 says that God raised Christ from the dead and seated him at his.

Why Do We Have Different Time Zones? Wonderopoli

Different algorithms Quadratic interpolation method. QBASIC listing References. Overview [ Top] This page describes an algorithm that will enable you to calculate the time of Moon rise and set and Sun rise and set, as well as the twilight times, for any latitude on the Earth's surface. The algorithm presented here will warn you if the Moon or. The order contains multiple items. There are a few reasons that an order with multiple items may have incorrect shipping costs: The combined dimensions of the items in the order may not fit into your chosen package preferences.Calculated shipping splits the order into multiple packages unless all items can fit into one package, which can increase shipping cost Zoning breaks up your home into different areas. Each zone has a thermostat or temperature sensor that automatically controls dampers in your ducts. You can use zoning to even out the temperature in your home or to set different temperatures for different rooms. Learn more about zoning. 2) Uninsulated or long runs of duct

Why does the Sun rise in the east and set in the west

The Moon has phases. That means it looks a little different to us each night during its one-month orbit of our planet. We describe how the Moon looks with terms such as Full Moon, First Quarter, and New Moon (which we can't really see, because the side that is lit faces away from us)


Fastest sunsets happen near the equinoxes

Here’s a natural phenomenon you might never have imagined. That is, the sun actually rises and sets faster around the time of an equinox. And the slowest sunsets (and sunrises) happen at or near the solstices. In 2021, the vernal equinox falls on March 20 at 09:37 UTC translate to your time zone.

The fastest sunsets (and sunrises) happen at or near the equinoxes. This is true whether you live in the Northern or Southern Hemisphere.

Sounds crazy, yes? But it’s true!

And, by the way, when we say sunset here, we’re talking about the actual number of minutes it takes for the body of the sun to sink below the western horizon.

Why does it happen? Keep reading.

Equinoxes and solstices, via Geosync. Top left: December solstice top right: March equinox bottom left: June solstice bottom right: September equinox.

At every equinox, the sun rises virtually due east and sets due west. That means – on the day of an equinox – the setting sun hits the horizon at its steepest possible angle. It’s that steep angle of the rising or setting sun that makes the sunrise or sunset happen faster.

How much faster? The duration of sunset varies by latitude. The sun always sets faster near Earth’s equator and more slowly at higher latitudes. But – to consider the change in the duration of sunset for just one latitude – let’s just think about the 40th parallel north (40 degrees north latitude). That’s the latitude of Denver, Colorado Philadelphia, Pennsylvania Beijing, China the Spanish island of Minorca in the Mediterranean Sea it passes just north of Ankara in Turkey and through the Sea of Japan and of course across many more places around the globe.

At the 40th parallel north, on the day of an equinox, the sun sets in about 2 3/4 minutes.

However, at that latitude, the solstice sun sets in roughly 3 1/4 minutes. At a solstice, the sun is setting farthest north or farthest south of due west. The farther the sun sets from due west along the horizon, the shallower the angle of the setting sun. That means a longer duration for sunset at the solstices.

So, wherever you are, enjoy these near-equinox sunsets, and stay focused! They’re among your fastest sunsets of the year.

The equinox is an event that takes place in Earth’s orbit around the sun.

Bottom line: The fastest sunsets of the year are happening now, around the time of the March equinox.


The Misunderstood Equinox

Can you balance an egg on the autumnal equinox? Does the Sun rise due east and set due west for all of us on Earth? Why did the date of the equinox change? How is it related to the Harvest Moon? Bob separates autumnal equinox facts from fiction.

We have an equinox coming up early in the morning on Tuesday, September 22, 2020. See all you need to know about the Autumnal Equinox.

There are a number of questions and misperceptions sent my way. Let’s clear this up, and talk a little about the reasons for the seasons.

A Moment in Time

The equinox happens at the same moment across the Earth (13:31 UTC ) which is pretty cool. It’s not an all-day event such as a birthday or holiday. The equinox is the moment the Sun crosses the celestial equator—that imaginary line in the sky above Earth’s Equator. At this instant, Earth’s rotational axis is neither tilted away from nor towards the Sun.

Of course, your “clock time” of this instant depends on your time zone (9:31 a.m. EDT , 8:31 a.m. CDT , 7:31 a.m. MDT and 6:31 a.m. PDT ).

Not Always the Same Date

And the calendar can affect the date itself as well. The Autumnal Equinox date is usually on the 22nd or 23rd. It varies slightly, since our Gregorian calendar doesn’t perfectly match up with the time it takes the Earth to orbin the Sun (365 days versus approximately 365 and ¼ days).

If you see a generic calendar stating different dates or times, it’s usually because a universal or different time zone is being used, often unwittingly. (Not true of the Almanac calendars.)

Are Days and Nights Truly Equal?

At the equinox, the Earth will angle perfectly sideways to the Sun. Neither pole will tip toward or away from it. And therefore, as the media never tire of reminding us, days and nights should theoretically be equal, right?

But this is never quite true. Our atmosphere bends the Sun’s image upward so much that it rises two or three minutes earlier and sets that much later than it would on an airless world, and those extra five minutes of daily sunshine push the true date of equality to a few days after the equinox.

Even then, it’s not strictly accurate to say day and NIGHT are equal, because of twilight. If useful daylight ends about an hour after sunset, and you add in the dawn twilight too, then most places don’t have equal day and night until around November 10. So we get more actual night than daylight for just three months, from then until mid-February.

Sunrise and Sunset on the Equinox

Never mind the day-night equality business. A more precise equinox event is that the Sun rises and sets exactly in the east and west—not southeast or northwest or anything else. It’s a time of precision, and an opportunity to correctly position your sundial. You know, that task you keep putting off.

And this happens no matter where you live on Earth, because we all see the same sky. We all see a due east and due west point on your horizon. That point marks the intersection of your horizon with the celestial equator – the imaginary line above the true equator of the Earth.

The Sun’s Winding Path

Another equinox phenomenon is that the Sun moves in a laser-straight line across the sky. A time exposure shows this nicely. By comparison, for the past six months, the Sun’s path has displayed an upward curve, concave to the north, like a giant smile. Starting right after the equinox, the Sun’s track across the sky starts to bend like a rainbow, with the concave part aimed downward.

That Harvest Moon

The full Moon closest to the September equinox is the Harvest Moon. This year, due to the timing of the equinox, it falls on Thursday, October 1, and the full Hunter’s Moon on Saturday, October 31. (That’s right—we’ll have a full Moon on Halloween night this year, and it will be a Blue Moon, too!)

At the Harvest Moon, there are shorter period between moon rises. This phenomenon occurs due to the low angle the Moon’s orbit around Earth makes with the horizon during this time of year.

  • Learn all about what makes the Harvest Moon so special here: The Harvest Moon
  • Read about both of October’s full Moons: October Full Moons

Eggs on the Equinox

As for the age-old idea that eggs are able to balance on end during the equinox but at no other time—that’s just silly! Why should the laws of gravity be repealed just because the Sun illuminates both poles equally that day? Still, it’s fun to consider, especially if it sparks conversation about the reasons for the seasons.

If you take the equinox so seriously that you have an equinox-obsessive personality, which psychologists call EOP , you’ll contemplate the idea of equality on September 22. That’s when our beloved Sun pauses momentarily, balanced and motionless, before lunging headlong toward the northern winter.


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