Question

Planets do not twinkle as stars, because

• A. planets are much closer to Earth than stars.
• B. planets are smaller in size than stars.
• C. a planet is not surrounded by gaseous atmosphere.
• D. a star is not surrounded by gaseous atmosphere.

Answer 1

The correct option is A planets are much closer to Earth than stars.

As the light from a star enters the atmosphere, it hits gas molecules and scatters (reflection and interference). Since, the star is so far away, we only see a tiny beam of light from it.
This beam gets scattered away from our eyes and then back into them almost like it is blinking on and off. It happens so fast that it just looks like it is twinkling.
Planets, on the other hand, are closer to us and send more light; if some of the light beams are scattered away, others still get through to us, so planets don't usually twinkle.