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 regarding large spheres of plasma undergoing fusion.
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Questions regarding the closest star to Earth, at the centre of the Solar System.
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Questions regarding points of extremely high mass density, which creates an extremely strong gravitational field from which light cannot escape.
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Questions regarding an object 'falling around' another object, due to a combination of gravity and momentum.
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Questions on astronomical objects orbiting a star massive enough to be rounded, not massive enough to cause fusion, and which have cleared its orbit of planetesimals.
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Questions regarding Earth's only natural satellite.
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Questions about the techniques and practice of observing the night sky.
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Questions regarding systems of large numbers of stars held together by gravity.
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Questions regarding the attractive force which exists between any two bodies of matter.
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Questions regarding the Sun and objects orbiting it.
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Questions related to the physical instruments for astronomical observations.
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Questions regarding the planet on which humans live; the third planet from the Sun.
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Questions involving the physics of the universe, especially the nature of astronomical objects, energy fields, and/or regions, rather than their positions or motions in space.
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Questions about the observation of celestial objects by non-professional astronomers.
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Questions regarding all of time and space and its contents.
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Questions about the origin, history, evolution and fate of the Universe.
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Questions regarding planets that lie outside the Solar System.
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Questions regarding electromagnetic radiation in the visible spectrum.
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Questions regarding relatively small rocky bodies in an orbit around the Sun.
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Questions regarding the amount of space between two objects, the units, or measurement thereof.
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Questions regarding the Milky Way Galaxy, the galaxy that Earth's solar system is in.
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Questions about observation performed in the radio frequency range of the electromagnetic spectrum (between 10 MHz and 1GHz).
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Questions regarding the 4-dimensional background structure of our universe.
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Questions involving reference frames, time scales, and how they are determined.
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Questions about photography of celestial objects by amateur or professional astronomers. Questions about photography of other objects are off-topic but might be asked on our sister site Photography St…
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Questions regarding a layer of gasses surrounding a celestial object.
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Questions on systems to uniquely determine position of a point or other geometric element on a manifold such as Euclidean space.
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The near-vacuum extending between the planets and stars, containing small amounts of gas and dust. Also called outer space to refer to the physical universe beyond the Earth's atmosphere.
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Questions about relativistic theory of gravity. General relativity describes gravity as a geometrical property of space and time.
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Questions regarding stars which increase suddenly in energy output due to an explosion which ejected much of its mass.
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Questions regarding the action of or an object rotating along an axis.
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Questions regarding the currently prevalent cosmological model for the origin of the universe.
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Questions about the increase with time of distance between two distant points in the Universe.
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Questions regarding Jupiter, the 5th and largest planet in the Solar System.
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Questions regarding Mars, the fourth planet from the Sun.
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Questions on celestial bodies that orbit planets.