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.

Questions regarding large spheres of plasma undergoing fusion.
Questions about the techniques and practice of observing the night sky.
Questions regarding the closest star to Earth, at the centre of the Solar System.
766 questions
Questions regarding points of extremely high mass density, which creates an extremely strong gravitational field from which light cannot escape.
698 questions
Questions regarding an object 'falling around' another object, due to a combination of gravity and momentum.
Questions regarding Earth's only natural satellite. For questions about the natural satellites of other planets, use the tag [natural-satellite].
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.
650 questions
Questions regarding systems of large numbers of stars held together by gravity.
613 questions
Questions related to the physical instruments for astronomical observations.
Questions regarding the Sun and objects orbiting it.
577 questions
Questions regarding the attractive force which exists between any two bodies of matter.
523 questions
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.
Questions regarding the planet on which humans live; the third planet from the Sun.
494 questions
Questions about the observation of celestial objects by non-professional astronomers.
Questions regarding planets that lie outside the Solar System.
Questions about the origin, history, evolution and fate of the Universe.
Questions regarding all of time and space and its contents.
Questions regarding electromagnetic radiation in the visible spectrum.
309 questions
Questions regarding relatively small rocky bodies in an orbit around the Sun.
Questions about observations performed in the radio frequency range of the electromagnetic spectrum.
Questions regarding the amount of space between two objects, the units, or measurement thereof.
266 questions
The application of ballistics and celestial mechanics to the practical problems concerning the motion of rockets and other spacecraft.
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…
235 questions
Questions regarding the Milky Way Galaxy, the galaxy that Earth's solar system is in.
228 questions
Questions on systems to uniquely determine position of a point or other geometric element on a manifold such as Euclidean space.
219 questions
Questions regarding stars which increase suddenly in energy output due to an explosion which ejected much of its mass.
209 questions
Questions regarding Mars, the fourth planet from the Sun.
Questions regarding the history of astronomy, including discoveries and scientists.
207 questions
Questions regarding the action of or an object rotating along an axis.
206 questions
Questions regarding Jupiter, the 5th and largest planet in the Solar System.
204 questions
Questions about relativistic theory of gravity. General relativity describes gravity as a geometrical property of space and time.
200 questions
Analysis of data is a process of inspecting, cleaning, transforming, and modeling data with the goal of discovering useful information, suggesting conclusions, and supporting decision making.
Questions about the measurement of light waves whereby the wavelength is classified by its position in the electromagnetic spectrum.
196 questions
Questions on celestial bodies that orbit planets.
189 questions
Questions regarding the 4-dimensional background structure of our universe.
189 questions
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…
182 questions
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