why do stars twinkle at night wikipedia
The twinkling of stars in our night sky is down to the EarthБs atmosphere. As light from the stars travels towards Earth it can easily move in a straight line, but once it starts travelling through the EarthБs atmosphere it gets bounced around in different directions by the particles in the air. For astronomers this twinkling can be a huge problem, especially when theyБre trying to accurately image a particular star. The more the star twinkles, the blurrier the image will be. If telescopes are launched into space then all images can be taken without EarthБs atmosphere in the way, but this is expensive. It is possible to use a system called Бadaptive opticsБ, when tiny motors alter the surface of the telescopeБs mirror to correct for this blur caused by the air. Answered by Megan Whewell, Education Team Presenter for the National Space Centre. Image courtesy of NASA Keep up to date with theб latest бreviews in All About Space Бб available бeveryбmonthбfor just бе4. 99. Alternativelyбyou canбsubscribeб
б for aб fractionб of theб price! Tags:, Stars twinkle because they are so far away from Earth that they appear as point sources even when seen through powerful telescopes. The light rays coming from them are refracted multiple times, making them look as if they were blinking. The sun and other planets, however, are quite close to us (relative to stars), and thus appear like disks.
Twinkle twinkle, little star, how I wonder what you are! Some rhyme, huh? Everyone must be familiar with that famous rhyme from Jane Taylor s poem The Star. It was a big part of childhood for many people. Well, it s not just a song for children; it s actually referring to a particular scientific phenomenon that has fascinated observers on Earth for thousands of years. AsPwe grew up, we were taughtPthat stars may not be like diamonds, but they do twinkle, right? They certainly appear to do so, but what about our closest star? The Sun is a star, the heart ofPour solar system, but we don t see the sun twinkling. PWhy do all the other stars in the night sky appear to twinkle, but our Sun never does? Why do stars twinkle, but the sun and planets do not? Short answer: Stars twinkle because they re so far away from Earth that when light from the stars passes through the atmosphere, it is bent countless times due to refraction, making it look like as if they were blinking. The sun doesn t twinkle because it s too close to Earth compared to other stars. Astronomers have provided a scientific name for the twinkling of stars: astronomical scintillation. The other stars that we see in the sky are located very far away from Earth. The Sun is definitely the closest star to Earth, sitting approximatelyP (0. 0000158 light years) away.
The next closest star, however, is located about from Earth, so that gives you some impression of how far awayPthose other stars truly are from Earth. The reason the Sun doesn t twinkle is because it s too close to the Earth, as compared to other stars. Due to this, unlike stars, the sun appears much bigger than a small point in the sky, and therefore, doesn t seem to twinkle. You see, Earth s atmosphere is so turbulent that images of all objects in the sky tend to swim. Consequently, a tiny point in space gets mapped to 2 or more points in space, which imparts that blinking effect to the point source. ( In other words, stars appear so small (thanks to their distance from us) that due to atmospheric refraction, it appears as if they are at more than one place, which, in turn, makes them look like as if they were blinking. The sun, however, is quite close and therefore looks more like a disk as opposed to a tiny point in the vastness of space. That s why atmospheric refraction doesn t play that big a role in how we perceive it from Earth, and hence, doesn t appear to blink. Why Do Other Stars Twinkle? Light from other stars crosses a very long distance to reach us and also passes through pockets of Earth s atmosphere, whichPvary in temperature and density. Our atmosphere is very turbulent, with streams and eddies forming, churning around, and dispersing all the time.
Every layer of Earth s atmosphere has air moving in different directions atPdifferent intensities. When light from stars passes through the atmosphere, it is bent due to refraction, which is why stars seem to twinkle when we stare at them. If viewed from outer space, you would not see the stars twinkling. This process is similar to watching a coin appear toPdance at the bottom of the swimming pool. This optical illusion occurs because the water in the pool bends the path of light emanating from the coin. Planets, just like the Sun, do not twinkle. Planets are also closer to the Earth than those distantPstars, so planets appear larger in comparison. Due to the planets closeness to Earth, the light coming from these celestial bodies does not bend much due to Earth s atmosphere. Therefore, the light coming from our solar system s planets does not appear to twinkle like stars. We should be very thankful to the Earth s atmosphere; aside from protecting us from harmful UV rays that could fry us in an instant, the atmosphere is why that sky full of stars appears to twinkle at night. Thankfully, this means that we can continue teaching that famous rhyme from Jane Taylor to future generations. It s a good poem it would be a shame to waste it!
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