Question

Why are stars twinkling ?

Answer 1

Actually the stars don't twinkle.
The stars are huge balls of fire. They are too far away from us to be visible as huge. The Earth has an atmosphere due to which stars seem to be twinkling.

Answer 2

Answer:

turbulence) in the atmosphere of Earth causes the starlight to get slightly bent as it travels from the distant star through the atmosphere down to us on the ground.