Planet
A planet is a large, round body orbiting a star that has cleared its path of most other material.
A planet is a large body that orbits a star, is massive enough for gravity to pull it into a round shape, and has swept its orbital path mostly clear of other objects. Our Solar System has eight planets: Mercury, Venus, Earth and Mars, which are rocky; Jupiter and Saturn, which are gas giants; and Uranus and Neptune, which are ice giants.
The planets grew from the disc of gas and dust around the young Sun. Dust stuck together into pebbles, pebbles gathered into planetesimals and planetesimals collided and merged into planets over millions of years. Meteorites are leftovers from this process, which is why they are so valuable: they let us study the building blocks directly.
Astronomers have also found more than 5,000 planets orbiting other stars, called exoplanets. Some are rocky like Earth, and comparing them with our Solar System helps us understand how planets form.
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Level: Beginner Ages 7 and up