Look at the sky on a clear night in a dark area and the stars seem to twinkle. But what is the science behind this phenomenon? What makes the stars twinkle?

The answer to the question of why stars shine is that they don’t. The twinkling we see has nothing to do with the stars themselves. Rather, it is 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 long way to reach our eyes on a clear night,” said Ryan French, a solar physicist at University College London in the UK. After our own star, the Sun – whose average distance from Earth is 150 million kilometers – the nearest star to us is Proxima Centauri, which is more than 4 light-years from Earth.

Why do some stars twinkle more than others?

On its 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 wobbly air before it reaches our eyes, causing it to twinkle,” French said.

So it is the Earth’s atmosphere that makes the stars appear to twinkle. In space, high above the atmosphere, the stars do not twinkle at all. Many factors affect how much a star appears to twinkle. One of the variables is where the star occupies in our field of view.

“Stars will shine brighter if their starlight travels through more air before reaching our eyes,” French said, so stars near the horizon appear brighter because their light has to travel through more atmosphere. to reach us.

Weather also plays a role. “Wet nights will also make the air thicker,” which makes the stars appear to twinkle more, French said, according to Live Science.

The twinkling we see has nothing to do with the stars themselves

These aspects guide astronomers when deciding where to locate the world’s biggest and best telescopes. “Observatories are placed in high, dry places to remove as much air as possible between the star and the telescope,” French said.

Ideal locations include the Atacama Desert in Chile, as well as the volcanic peaks of Hawaii and the Spanish Canary Islands. When looking at the night sky, you may also notice that some stars seem to change between different colors as they twinkle.

“Starlight is refracted a bit by the atmosphere, which can cause it to change color,” French said. This effect is more visible in brighter stars.

You may also notice a few stars that don’t twinkle at all. That’s because these are actually planets. “Unlike stars, planets are not point sources in the sky, they are wide,” French said. “This is because they are much closer to us.” In other words, they are too large in the night sky for the atmosphere to make them appear to twinkle.

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