What distorts the light coming from a star is temperature variations in the air. As you probably know already, air temperature varies a great deal.
The temperature variations in the air bends the star light so that it seems to change in brightness and the stars appear to twinkle. People got the idea that stars have points because they twinkle. The scientific name for the twinkling of stars is stellar scintillation (or astronomical scintillation).
Most scintillation effects are caused by anomalous atmospheric refraction caused by small-scale fluctuations in air density usually related to temperature gradients.
Stars closer to the horizon appear to twinkle more than stars that are overhead. This is because the light of stars near the horizon has to travel through more air than the light of stars overhead and so is subject to more refraction.
Actually, stars are huge balls, like the sun. If we could see them from outer space, where there is no atmosphere, we would see stars shining with a steady light.
Will we ever travel to the stars? Traveling to the stars is very difficult because they are so far away. The nearest star is 25,300,000,000,000 miles (about 39,900,000,000,000 kilometres) away. It would take the fastest rockets that we have thousands of years to reach it. It is always possible that sometime in the future people may find a way to travel to the stars. But right now we just do not have the technology.
Content for this question contributed by Cindy Cholovich, resident of Pittsburgh, Pennsylvania, USA
