solar systems
The possessive form of the noun "planets" is "planets'."
It is highly unlikely for planets to form on another planet. Planets typically form from material surrounding a star, not from existing planets. However, moons can form around planets through processes such as accretion or capture.
planets
no
None Stars are gas Planets are solid
No. Planets form by a process called accretion, which is driven by gravity. Nobody creates planets.
No
They don't - new born stars and planets are formed together.
Out of an accretion disk leftover from the solar nebula. Small particles bump together and collect until they form planets.
MVEMJSUN
Parts of other planets
A solar system!