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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infinitely dense.
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Questions regarding the future and ultimate fate of the Universe, including the heat death, Big Freeze, Big Rip, or Big Crunch.
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about the lack of evidence for alien life, despite the growing evidence that suitable planets are reasonably plentiful.
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the larger of Mars's two moons, being 11km in diameter. It is also the nearer to the planet's surface, and orbits the planet every 7 hours 39 minutes. It is predicted that within 50 million …
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the group of galaxies that includes the Milky Way among others.
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Questions regarding the use of a reflective surface, for example in optics.
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Questions about flow regime in astrophysical gas characterized by chaotic properties.
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A map of the surface features of something.
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