The word planet comes from the Greek πλανήται (planḗtai) 'wanderers'. In antiquity, this word referred to the Sun, Moon, and five points of light visible to the naked eye that moved across the background of …

Mar 12, 2025 · What is a Planet? The word goes back to the ancient Greek word planēt, and it means "wanderer." A more modern definition can be found in the Merriam-Webster dictionary which defines …

By 1930, nine planets had been discovered: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. But what exactly is a planet? It seems like an easy question. After all,...

Dec 29, 2025 · Planet, broadly, any relatively large natural body that revolves in an orbit around the Sun or around some other star and that is not radiating energy from internal nuclear fusion reactions. …

In ancient Greek, the word planet simply meant “wanderer,” and could be applied to any object that appears to move against the background of fixed stars. Along with the five naked-eye planets, this …

Therefore, the word “planet” as used in planetary geology implies: a planet is a world too small to be a star (meaning it never produced nuclear fusion) and is big enough to be round due to its self-gravity.

May 21, 2024 · Scientists believe planets begin to form when a dense cloud of dust and gas, called a nebula, spins around a newly formed star. Gradually, gravity causes the bits of matter in the nebula …

Oct 18, 2023 · A quick guide to planets, including the eight in our solar system, how they form, and how many could be in the universe.

May 28, 2025 · What is a planet? The word goes back to the ancient Greek word planēt, and it means "wanderer." A more modern definition can be found in the Merriam-Webster dictionary which defines …

This definition, which applies only to the Solar System (though exoplanets had been addressed in 2003), states that a planet is a body that orbits the Sun, is massive enough for its own gravity to make it …