If you look up at night and see stars, they appear to twinkle, but that's only because you're standing on planet. If you were in space, they wouldn't. Here's a great article from LIVESCIENCE explaining the phenomenon... and why planets don't twinkle.
Stars don't actually twinkle
By Colin Stuart LIVE Science, June 2022
Stars don't twinkle. The twinkling we see has nothing to do with the stars themselves. Rather, it's a result of how we see them from our perspective on Earth.
Because stars are so far away, we see them as tiny points of light in the night sky.
"Starlight travels a great distance to reach our eyes on a clear night," said Ryan French, a solar physicist at University College London in the U.K. After our own star, the sun — whose average distance to Earth is 93 million miles (150 million kilometers) — the nearest star to us isProxima Centauri, which is over 4 light-years from Earth.
On the way to our eyes, this light from distant stars encounters Earth's atmosphere — the key driver behind the twinkling effect.
"As this point of light reaches the atmosphere, it passes through layers of wobbling air before reaching our eyes, causing it to twinkle," French said.
So it's Earth's wobbling atmosphere that makes stars appear to twinkle. In space, high above the atmosphere, stars don't twinkle at all. (That's one reason why the Hubble Space Telescope was sent into orbit: It could get sharper images of space without the images being distorted by atmospheric turbulence.)
Why some stars twinkle more than others Many factors affect how much a star appears to twinkle. One variable is the star's place within our field of view.
"Stars will twinkle more if their starlight travels through more air before reaching our eyes," French said, so stars near the horizon appear to twinkle more because their light has to journey through more atmosphere to get to us.
Weather also plays a role. "Humid nights will also cause the air to be thicker," making stars appear to twinkle more, French said.
When you look up at the night sky, you may also notice that some stars appear to shift between different colors as they twinkle. Sirius, the brightest star in Earth's night sky, is a classic example. "Starlight gets refracted [bent] by the atmosphere a little bit, which can cause it to change color," French said. This effect is more noticeable with brighter stars.
You may also notice a few "stars" that don't twinkle at all. That's because they are actually planets. "Unlike stars, planets are not point sources in the sky, but have width," French said. "This is because they are far closer to us." In other words, they are too big in the night sky for the atmosphere to make them appear to twinkle.
However, if you look at the planets, or even the moon, through a telescope, you'll still see them appear to shimmer, as the light you're seeing has been jostled by the atmosphere on its way to your eyes.
Original article on Live Science.
No comments:
Post a Comment