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Sunsets have always been such marvelous sights to behold. There are some places such as the Atacama desert in Chile, the Matterhorn in Switzerland and Isle of Skye in Scotland that are famous for their exceptionally beautiful sunsets. Most of us are very fond of sunsets. However, you may want to know the science behind sunsets starting with the time it takes for the sun to set.
So, how long does it take for the sun to set? The Sun takes approximately 150 to 200 seconds (2 to 3 minutes) to fully go below the horizon (once it has already touched the horizon). However, the exact time taken by the Sun to fully set depends on various factors such as thickness of the atmosphere, time of the year and the latitude.
In this article, we will answer all the questions generally asked around the sunset:
- How long does it take for the Sun to set?
- Where does the Sun actually set?
- Is the Sun’s touching of the horizon called sunset?
- What does sunset time mean?
Let’s get started!
The Science Behind Sunsets
To understand the science behind sunsets, let us first understand what sunsets are.
Sunsets, also known as nightfall or dusk refers to the daily phenomena when the Sun disappears below the horizon; this takes place due to the rotation of the earth.
We see many changes in the color of the sky as the sunset time draws nearer. The color of the sun changes along with the color of the sky.
There is a considerable drop in the brightness of the Sun. These changes in the colors are due to Earth’s atmosphere. The sun’s light needs to pass through a denser layer of atmosphere to reach us when the sun starts to move towards the horizon.
The wavelengths of light that are bluer in comparison to the other get scattered and only the red wavelengths reach our eyes. This movement of the sun towards the horizon makes the sky appear redder as only redder wavelengths are left behind while blues, greens and oranges are left behind.
You will find the best sunsets in fall and winter or in cold places where there is comparatively less moisture in the atmosphere. The presence of clouds in the sky also results in phenomenal sunsets as these clouds become screens for the colours.
How Long Does The Sun Take To Fully Set?
The time taken by the Sun to fully set depends on various factors such as thickness of the atmosphere, time of the year and the latitude. The Sun takes about approximately 150 to 200 seconds (2 to 3 minutes) to fully go below the horizon (once it has already touched the horizon).
The sun travels across the sky at a rate of 1 per 340 seconds as the earth rotates. The latitude of the place has a crucial role to play in the time taken by the sun to set. The closer the place is to the equator, the faster the sun sets.
Also as mentioned above while explaining the science behind sunsets, the atmosphere plays a significant part. Latitude of the place and thickness of the atmosphere are directly related to each other. The farther the place is from the equator, the slower is the sunset.
Places that are close to the Antarctic Circle experience unusual sunsets.
The sun partially sets and rises again in a very short time. At the Pole, every day the sun moves in horizontal circles in the sky. There is permanent sun on the sky during summers and as winter draws nearer, the sun starts getting more and more close to the horizon and takes several days to set.
What Does Sunset Time Mean?
In astronomy, sunset time refers to the time when the last tip of the sun’s upper limb goes below the horizon.
What most of us don’t know is that the sun actually has set a few minutes before we see it. This is because the rays of the sun get bent due to the atmosphere as the sun goes down. This deflection of the rays makes the sun appear as though as it is still above the horizon even though it has already gone below it. The solstices- both summer and winter are based on sunset time.
When either of the poles of the earth is most tilted facing the sun, it is known as summer solstice or midsummer. This phenomenon occurs in each hemisphere of the earth twice a year, one time in each hemisphere.
For that particular hemisphere, when the Sun is highest in the sky, it is the day of summer solstice. That day has the longest period of daylight and the sunset takes very late.
After the summer solstice, the days start to get shorter. As the name itself suggests, summer solstice takes place during summer. It is called June solstice in the northern hemisphere and December solstice in the southern hemisphere. Every year the summer solstice falls somewhere between the 20th and 22nd of June for the northern hemisphere and the 20th and 23rd of December for the southern hemisphere.
In a very similar manner, when one of the poles of the sun is most tilted away from the atmosphere, it is known as winter solstice or midwinter. The days are shortest on the days of winter solstice and therefore the sunset time arrives quite early in the day. After the winter solstice, the days start to get longer. When there is summer solstice in northern hemisphere, there is winter solstice in southern and vice versa.
That is why the dates are the exact opposite for each hemisphere.
Where Does The Sun Set At?
We have always learnt from childhood that the sun rises in the east and sets in the west. So it doesn’t matter whether you are in the northern hemisphere or the southern hemisphere, the sun will always rise in the east and set in the west.
In fact, the stars and the moon also rise in the east and set in the west because the earth rotates in the east. Although, technically speaking, neither does it rise, nor does it set.
The Sun is the center of the solar system and stays constant in its place. It is the earth that rotates around it in a west-east motion. That is why, if you were on Venus, you would see the sun rise in the west and set in the east because Venus rotates in the east-west motion.
You’d be surprised to know that the sun appears to rise exactly in the east and set exactly in the west on only two days of the year. These two days are called the equinoxes.
When the earth’s rotation axis is tilted by exactly 23.5 with respect to its orbital plane, the earth’s surface splits into two equal halves, where one part is in the light and one part is in the dark. This alignment occurs only twice a year and these two days are called the spring and fall equinoxes.
How Is Sunset Different From Twilight?
Often people tend to mix up sunset and twilight because twilight is often used as a synonym of sunset. However, sunset and twilight are two different phenomena.
Twilight is actually the time after the sunset and before night. Twilight is divided into three stages. The first stage is called Civil twilight, the second one Nautical twilight and the third one Astronomical twilight.
The brightest stage of twilight is called Civil twilight. It starts from the instant the sun goes down the horizon and lasts until the sun is 6 below the horizon. It usually last for thirty minutes but can also be longer or shorter depending on various factors such as location and time of the year.
The stage right after the civil twilight is called Nautical twilight. It occurs when the sun is between 6 to 12 below the horizon. This stage also lasts for about thirty minutes.
The last stage of twilight is called astronomical twilight. It occurs when the sun is between 12 to 18 below the horizons and lasts for about thirty minutes.
Some More Facts About Sunsets
- Sunsets appear more colorful due to pollution: If you are wondering how bizarre it is, you’re not wrong. However, smoke particles in the air single out colors better and hence colors like pink, orange and red appear more vivid. But if there is too much pollution, the sky turns hazy and it becomes difficult to see the sunset.
- Colors of the sunset are indications of the weather: The redder hues indicate that the air is clear on the west and that the weather will be good in the morning but there will be low pressure storms on the east.
- Sunsets are prettier after storms: Sunsets look prettier after storms because the big pollutants present in the air are washed away after the rainstorms.
- Sunsets are different on other planets: The sunsets are different on other planets of the solar system. For example, if you were to see a sunset on Mars, the sun would appear two third of the size it appears on our planet. This is because Mars is at a greater distance from the sun. Mars has a thin atmosphere and hence the scattering of light is different there. Also, sunsets last longer on Mars than on earth.
I hope this article was helpful to you and answered some of your questions around sunsets.