Planetesimal formation.
gas
The planets formed from a disk of gas and dust that surrounded the sun as it formed. This gas and dust clumped together to form the solar system. Two planets cannot occupy orbits that are too close together. If they do, interactions through gravity will either cause them to collide or get moved to different orbits.
Planets not orbiting a star but instead orbiting the galactic center are referred to as rogue planets, or nomadic or interstellar planets.
Astronomers.
Astronomers
There were nine planets. Then astronomers got together and decided what to do with Eris, a dwarf planet that was discovered. They decided to make a definition for what is a planet. That led to Pluto being demoted to a dwarf planet.
Pieces of rock clumped together to make big ones
Here is one lie about how planets are formed: One day Zeus took a big doodoo. All his doodoo was floating in space and they clumped together to form the planets.
gravity clumped stars together, created planets and stopped everything from moving at the speed of light
Teams of astronomers have studies all possible planets.
Astronomers use a telescope to view planets directly.
Many astronomers, historians, regular people, and scientisis know about the planets in our Solar system.
On one of the explorer's planets
astronomers
The planets formed from a disk of gas and dust that surrounded the sun as it formed. This gas and dust clumped together to form the solar system. Two planets cannot occupy orbits that are too close together. If they do, interactions through gravity will either cause them to collide or get moved to different orbits.
before the teloscope was invented what were ancient astronomers able to learn about the planets ?
Because the ancient Greek astronomers were one of the first astronomers to discover the planets. As they looked at the planets over time they moved into different places. The planets seemed o orbit the Sun so the Greek astronomers called them planets, which meant :wanderers.
Planets not orbiting a star but instead orbiting the galactic center are referred to as rogue planets, or nomadic or interstellar planets.