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 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 about observation performed in the radio frequency range of the electromagnetic spectrum (between 10 MHz and 1GHz).
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Questions regarding the property of astronomical objects that determines their inertial resistance and gravitational interaction with other bodies.
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Questions regarding the phenomenon in the early universe characterized by an extreme expansion of space.
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Questions regarding an object's movement, or its distance traveled relative to the time taken.
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gravitationally linked and orbit around their barycenter.
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Questions about the dynamical processes leading to the assembling of a celestial object.
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Questions related to the physical processes involved in or to the observations of the process of forming a star.
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a measurement of the average kinetic energy of the molecules in an object or system. In simpler words: it's the degree or intensity of heat present in a substance or object that is comm…
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Questions regarding the planet Venus, the second planet from Earth's sun.
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Questions related to the evolution of stars.
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Questions regarding a degenerate star that is mainly composed of neutrons.
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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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Questions about solar system planets/moons and exoplanets that exhibit similar features to the Earth.
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Questions regarding magnetic fields.
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Questions on objects passing through the atmosphere which leave visible wakes of incandescent material.
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Questions regarding interactions between galaxies or between major parts of a galaxy.
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Questions regarding the history of astronomy, including discoveries and scientists.
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Questions regarding the universe shortly after it's formation
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a process of inspecting, cleaning, transforming, and modeling data with the goal of discovering useful information, suggesting conclusions, and supporting decision making.
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Questions regarding the as-yet-unknown energy permeating the universe that is responsible for its expansion.
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Questions regarding the cosmic microwave background, or CMB, the leftover radiation that is taken by many as proof of the Big Bang.
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Questions regarding massive planets composed of layers of gases, such as hydrogen and helium, surrounding a solid/liquid core.
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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 about photography of celestrial objects by amateur astronomers.
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Questions regarding casually watching the stars.
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Questions about Saturn, the 6th planet in Earth's solar system.
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For questions about objects or phenomena outside Earth, generally on other planets.
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Questions on celestial bodies that orbit planets.
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A collection of ionized gases and dust in interstellar space
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Questions regarding the former 9th (now dwarf) planet Pluto.
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Questions about the complete or partial blocking of the sun by the moon.