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 gas undergoing fusion.
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Questions regarding Luna, Earth's moon and only natural satellite.
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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 regarding the closest star to Earth, centre of our Solar System.
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Questions regarding systems of large numbers of stars held together by gravity.
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Questions regarding the planet on which humans live, the third planet from the sun.
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Questions regarding the earthly Sun and objects orbiting it.
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Questions regarding the attractive force which exists between any two bodies of matter.
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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 celestial bodies in orbit around a star.
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Questions regarding the space in which all mass is thought to exist.
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Questions related to the physical instruments for astronomical observations.
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Questions regarding the action or process of observing a single object carefully to glean information.
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Questions about the observation of celestrial objects by non-professional astronomers.
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Questions regarding electromagnetic radiation in the visible spectrum.
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Planets that lie outside our solar system.
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Questions about the origin, history, evolution and fate of the Universe.
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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 4-dimensional background structure of our universe.
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Questions regarding the Milky Way Galaxy, the galaxy that Earth's solar system is in.
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Questions regarding the currently prevalent cosmological model for the origin of the universe.
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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 regarding the action of or an object rotating along an axis.
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Questions regarding Mars, the fourth planet from the sun.
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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 about the increase with time of distance between two distant points in the Universe.
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Questions regarding a layer of gasses surrounding a celestial object.
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Questions regarding relatively small rocky bodies in an orbit around the Sun.
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Icy bodies that usually consist of methane, water, and other materials that originate from beyond the jovian planets, and occasionally fall into the inner solar system giving off a massive tail as mat…
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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 about observation performed in the radio frequency range of the electromagnetic spectrum (between 10 MHz and 1GHz).
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Questions related to the phenomenon whereby electromagnetic radiation (such as visible light) generated by an object moving away from an observer will have increased in wavelength (i.e. shifted toward…
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Questions regarding the phenomenon in the early universe characterized by an extreme expansion of space.