how come planets in the sky dont twinkle and stars do?

Answer 1

Ever notice how a coin at the bottom of a swimming pool seems to wobble from side to side? This phenomenon occurs because the water in the pool bends the path of light from the coin. Similarly, stars twinkle because their light has to pass through several miles of Earth's atmosphere before it reaches the eye of an observer. It is as if we are looking up at the universe from the bottom of a swimming pool. Our atmosphere is very turbulent, with streams and eddies forming, churning around and dispersing all the time. These disturbances act like lenses and prisms that shift the incoming light from a star from side to side by minute amounts several times a second. For large objects like the moon, these deviations average out. Stars, in contrast, are so far away that they effectively act as point sources, and the light we see flickers in intensity as the incoming beams bend rapidly from side to side.

Answer 2

Our atmosphere consists of several parallel layers of varying densities with the most dense layer at the bottom and the top most layer being the least dense layer.When the light from a star passes through these layers they are continuosly refracted.So when it reaches the eye of an observer,it looks as if coming from a point which is only an apparent position(not actual position)of the star.
The parellel layers of the atmosphere is not steady.They intermingle with one another constantly thereby changing their densities.Some layers are hotter than others with the result that the star light is bent in different ways at different angles changing the apparent position of the star .
As long as the star is within the line of sight of the observer,it is visible but when the image falls ouside the line of sight,it is no longer visible.These changes in the apparent position of the star are continuosly happening, which gives rise to the "blinking " effect.
Similarly, planets apparent position also changes with the changes in the density of the layers.But planets are comparatively are close to the earth and hence the size of their apparent images are fairly larger.Because of the bigger size of the image, they never fall outside the line of sight of the obsever.Hence they do not blink like stars.

Answer 3

A Star as sen from earth is a point source, while a planet has discernible extent. Due to atmospheric turbulence a point source appears wavering or twinkling. In a source that is spread out the twinkle is evened (averaged) out to make it look steady.

Answer 4

The stars twinkle because of small atmospheric cells caused by differences in temperature that act like little lenses. Since stars are mere pinpoints, the lenses act to scatter the light all over. The planets don't twinkle because they are actually little circles that are larger than these atmospheric cells.