sTARs

[leonardo shawon]

why do stars twinkle?

Why do the number of stars vary?

[mubtasim123]

why do stars twinkle?

"Stars twinkle because of turbulence in the atmosphere of the Earth. As the atmosphere churns, the light from the star is refracted in different directions. This causes the star's image to change slightly in brightness and position, hence "twinkle." This is one of the reasons the Hubble telescope is so successful: in space, there is no atmosphere to make the stars twinkle, allowing a much better image to be obtained.

Planets do not twinkle the way stars do. In fact, this is a good way of figuring out if a particular object you see in the sky is a planet or a star. The reason is that stars are so far away that they are essentially points of light on the sky, while planets actually have finite size. The size of a planet on the sky in a sense "averages out" the turbulent effects of the atmosphere, presenting a relatively stable image to the eye."

January 1999, Dave Kornreich (more by Dave Kornreich)
sourcehttp://curious.astro.cornell.edu/question.php?number=114

[samiul_samin]

Why do the number of stars vary?

Because we are moving and they also are moving.It also varies for their death and many other causes.