Depending on your location, you can see more than 6,000 stars on a clear night. Some are smaller than others and makeup constellations too. In this article, you can learn more about stars and why they appear to twinkle in the sky.
Earth’s Atmosphere
One important thing you need to know and understand about the stars is that you view them through the Earth’s atmosphere. The atmosphere consists of several different types of gases that come together to surround the planet. When astronauts travel through space, NASA will often mention that they passed through the atmosphere as they left and came back. This affects the light that we can see in space too and changes how we see the stars.
Atmosphere and Turbulence
If you ever flew on a plane before, you likely encountered turbulence. This can make the plane shimmy and shake and give you a little scare. Turbulence refers to changes in the way air moves around an object such as your airplane or a planet. Starlight refers to the light that surrounds a star. The turbulence in the atmosphere can affect a star and limit the amount of light that reaches your eye. This can make it appear as though the stars move are bright and then dim, which gives them a twinkling effect. The brightness of a star does not change in space though. It remains constant.
On the Horizon
A good way to get a look at how stars can twinkle is with a spot on the horizon. The closer you are to the horizon, the closer the stars appear to the Earth. You might notice that the stars you see here twinkle more than the ones you see at home do. This is because the stars near the horizon are farther away from the atmosphere. All those excess gases make the stars appear as if they twinkle more than they do.
Hubble Telescope
Thanks to the Hubble telescope, astronauts got a good look at the stars. This telescope sent images back to the Earth that astronomers used to pinpoint the location of stars and to determine the distance between different constellations and planets. When you look at some of the photos that Hubble took, you can see that the stars all have the same brightness and that they don’t twinkle.
Planet vs. Star
Have you ever used a telescope to view the sky and spotted something that you weren’t sure was a planet or a star? An easy way to figure out what that object is with a look at whether it twinkles. Planets are larger than stars and do not suffer the same effects from turbulence. If you see something in the sky that looks small but does not twinkle, it’s a planet. Planets also tend to look more stable than stars.
North Star
Polaris is the North Star and one of the most important parts of the Big Dipper. Explorers in the past identified and gave the star its name because they believed that it would guide them north and to their homes. Polaris is not only one of the brightest stars in the sky, but it’s also one that appears to twinkle more than those in the surrounding area do. When you trace around those stars, you’ll form the outline of a constellation that seemingly shows a dipping cup. Not far away from the Big Dipper is the Little Dipper, which is a smaller version of that constellation.
Stars Don’t Twinkle
As much as you might like the idea of stars twinkling in the sky, the only reason they look that way is because of the turbulence in the Earth’s atmosphere. That turbulence reduces the brightness of the star and can make the human eye perceive the star as twinkling or shifting between dim and bright settings. Stars remain constant, which you can see through photos taken in space.