Gravity
There are in fact many planents within our Solar System that encompass a ring system, however Saturn is the most well known of these.
Mars.
The one with no moon
1.5billion years old
Gravity
yes aliens :)
Because they "wander" through the sky....
rocks, the other planents
the gas giants and the outer planents
neptune is the coldest planet as is the most far planent. pluto is not a planet.
Pluto, Ceres, Eris, Makemake. New ones are being added all the time.
orbits around planents or burn up as it gets close to the sun.
Because they emit energy themselves due to various chemical reactions on their surface or core. Planets, on other hand reflect the energy from the stars.