Question

looking up at the sky how can you distinguish between a planet and A Star?

Answer 1

The simplest way to distinguish between a planet and a star by just looking at the sky is to look at its brightness. The one which would be twinkling and will look bright will be the star and the somewhat dull one would be a planet..

Answer 2

planet does twinkle like a star and it comes very rarely while a star appears twinkling and could be daily seen in the night