1. Shape: a planet has always enough mass to be spherical due to its own gravity.
2. Atmosphere: allthough some planets (Pluto, Mercury) have a very thin atmosphere; they still have, so they are considering as planets.
3.
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| The characteristics of a space object which called planet | ||||
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| First, I have to say, that there are many arguments about which space objects should considered as planets and which should not. Due to this, I will just inform you about the characteristics that all, or at least the most, astronomers agree that a space object should have, to consider as a planet. 1. Shape: a planet has always enough mass to be spherical due to its own gravity. 2. Atmosphere: allthough some planets (Pluto, Mercury) have a very thin atmosphere; they still have, so they are considering as planets. 3. |
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