Science has come a long way from what it used to be. Scientist come up with new technology all the time, BIG TELESCOPES!!
The galaxis are bigger than planetary nebulae, that are bigger than planetary systems.
A sun is a star that is the center of a planetary system.
The gears in a planetary gear system are the drive gear, ring gear, and planetary gear.
It would be truly astonishing if the mechanism that produced planets in our solar system had done so in only one instance in the entire universe, so no one was really surprised when they were actually found (though what was found ... "Hot Jupiters" ... was a bit of a surprise).
It makes up about 70% of all the planetary matter in the solar system.
planetary science
A system of celestial bodies grouped around a sun.
Because it is the planetary system of Sol, another name for the Sun.
ptolemaic
planetary
The sun
Retrograde Motion