Question

Why do planets do not seems to twinkle as the stars seems to twinkle only because of the air current ?

Answer 1

Stars twinkle because they are so far away from Earth that they appear as point sources even when seen through powerful telescopes. The light rays coming from them are refracted multiple times, making them look as if they were blinking. The sun and other planets, however, are quite close to us (relative to stars), and thus appear like disks.