What is the evidence that suggests planetary systems are common in the universe?

1 Answer
May 21, 2016

By detecting planets using the transit method.

Explanation:

As far as we can tell, most sun-like stars have a planetary system.

The Kepler space telescope was tasked with finding planets using the transit method - observing periodic dips in the brightness of stars caused by planets moving in front of them. These dips in brightness are about 1 part in 10000. To do this it has to keep focused on the same area of the sky for an extended period of time.

What is has observed is that the vast majority (I think 80% plus) of sun-like stars have planets orbiting close to the star.