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It's a simple question with a complicated answer. 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 a planet as "any of the large bodies that revolve around the Sun in the solar system."
One idea is to simply define a planet as a natural object in space that is massive enough for gravity to make it approximately spherical. But some scientists objected that this simple definition does not take into account what degree of measurable roundness is needed for an object to be considered round.
A planet is defined as a celestial body that (a) is in orbit around a star, (b) has enough mass for its gravity to create a round shape, and (c) has cleared its neighborhood of smaller objects.
21 Μαΐ 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 to clump together. Slowly, these clumps accumulate and grow. Eventually, these clumps become planets.
The planets in our solar system are shown from top to bottom: Mercury, Venus, Earth (and our moon), Mars, Jupiter, Saturn, Uranus, and Neptune. What is a Planet? Learn about Earth's...
27 Ιουν 2019 · What Is a Planet? The Short Answer: A planet must do three things: it must orbit a star, it must be big enough to have enough gravity to force a spherical shape, and it must be big enough that its gravity cleared away any objects of a similar size near its orbit. This cosmic cloud, called Sharpless 2-106, is an area where stars (and planets) form.
1 Ιαν 2007 · In short, "planet" is not an arbitrary category but an objective class of celestial bodies. Astronomers' reevaluation of the nature of planets has deep historical roots. The ancient Greeks...
