The one with no moon
Earth, Venus, Mars, Io (moon of Jupiter), and Triton (moon of Neptune) are known to have volcanoes. Volcanic activity on these planets and moons can vary in type and intensity.
Mars.
Gravity
yes aliens :)
Because they "wander" through the sky....
rocks, the other planents
the gas giants and the outer planents
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.
There are in fact many planents within our Solar System that encompass a ring system, however Saturn is the most well known of these.
Its not necessarily that the closer planets are travelling faster. 1. The farther planets have a lot more mass, so they're likely to move a bit slower. 2. They are much farther away so the suns gravity is not as powerful as it would be if they were closer. 3. Its mainly about the distance they have to travel. The distance around the sun for the closer planets is much smaller so they're bound to make a full revolution much faster.