Dear Tom,
Why do stars twinkle?
Connie Jorden

Dear Connie,
Stars twinkle because of their very great distance from the Earth. A star’s light is literally only a point in the sky and its light comes through the atmosphere to our eyes from exactly the same direction. The star’s light is bent in the same way turbulence affects air. A star will “disappear” briefly when its light is bent off course on its way to our eyes, then reappear again when its light is not bent off course.  Atmospheric turbulence consists of varying winds, different temperatures and different densities along the path a star’s light takes to our eyes. Planets in our Solar System do not twinkle because they are much closer to the Earth, appear larger and do not appear as points. Their light comes to us along many paths.