Half as many as in 1594 centimeters.
Probably, but impossible to tell as we are only just seeing planets within our own galaxy.
The number of planets is not known. The number of stars is not known either, nor if all have planetary systems. Certainly many billions of billions.
1 inch= 2.54 centimeters
18 centimeters is 18 centimeters.
15cm
Infinitely many.
All of them
All planets have gravity to some degree due to their mass. Gravity is what keeps objects, including planets, in orbit around the sun.
Neptune has only 1 sun, like all planets
No many like Mars have no atmosphere at all.
All of them.
Half as many as in 1594 centimeters.
All of them
All planets have a core.
There is 15 centimeters in 15 centimeters
There are 10 centimeters in 10 centimeters.