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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Questions about the "adulthood" of stars. The main sequence is a distinctive band of stars that appears in a color-magnitude plot (known as Hertzsprung-Russell diagram). Stars appear in the main seque…
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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 regarding the process of accurately finding your location, and getting to another place by planning and following a map.
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Questions about the dwarf planet, and the largest asteroid n the Solar System, comprising 1/3 of the mass of the asteroid belt. Ceres orbits between Mars and Jupiter.
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a relatively inexpensive Newtonian telescope, in which the tube assembly slips freely in the lower base.
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Questions regarding atmospheric conditions on either Earth or on other planets.
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Questions regarding a theoretical 'tunnel' through spacetime which could potentially allow time travel.
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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 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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Second lightest element in the periodic table
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Questions regarding the National Aeronautics and Space Administration, the American civilian space agency.
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Questions regarding the possible existence of other universes.
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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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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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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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