A tag is a keyword or label that categorizes your question with other, similar questions. Using the right tags makes it easier for others to find and answer your question.

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like stars but never achieve nuclear fusion because they are too low-mass.
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Questions about the early phases of the star formation process. A protostar is a large mass of gas that results of the contraction of a molecular cloud.
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the Andromeda Galaxy. A spiral galaxy and the largest member of the local group of galaxies. M31 is currently about 2.2 million light years from the Milky Way, but is approaching and is expecte…
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Questions about the German astronomer famous for his three laws of planetary motion. Do not use this tag for questions about the Kepler spacecraft.
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Questions regarding the process of accurately finding your location, and getting to another place by planning and following a map.
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Questions regarding a family of extremely low-mass, electrically neutral particles described in the Standard Model of particle physics.
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Questions regarding structures designed to aid in the observation of astronomical objects.
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Questions to do with how new atomic nuclei are created inside the universe.
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Questions about the apparent displacement of a celestial body with respect to its background when observed along two different lines of sight.
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Questions regarding the National Aeronautics and Space Administration, the American civilian space agency.
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Space debris (also known as "orbital debris", "space junk", or "space waste") is the collection of defunct objects in orbit around Earth and includes everything from spent rocket stages, old satellite…
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Second lightest element in the periodic table
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Questions about the chances of collisions between two objects or groups of objects, based on factors such as velocity, mass and number density.
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any minor planet in the Solar System that orbits the Sun at a greater average distance (semi-major axis) than Neptune.
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Questions regarding a theoretical 'tunnel' through spacetime which could potentially allow time travel.
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Questions about large, dense, massive collections of stars orbiting galaxies, thought to have formed in the early universe.
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Questions about Europa, a moon of Jupiter with a planet-wide ocean under a thick ice crust.
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Questions regarding the possible existence of other universes.