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.
Questions regarding points of extremely high mass density, which creates an extremely strong gravitational field from which light cannot escape.
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.
671 questions
Questions regarding systems of large numbers of stars held together by gravity.
Questions related to the physical instruments for astronomical observations.
Questions regarding the Sun and objects orbiting it.
Questions regarding the attractive force which exists between any two bodies of matter.
540 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.
515 questions
Questions regarding the planet on which humans live; the third planet from the Sun.
508 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.
423 questions
Questions regarding all of time and space and its contents.
331 questions
Questions regarding electromagnetic radiation in the visible spectrum.
313 questions
Questions regarding relatively small rocky bodies in an orbit around the Sun.
302 questions
Questions about observations performed in the radio frequency range of the electromagnetic spectrum.
286 questions
The application of ballistics and celestial mechanics to the practical problems concerning the motion of rockets and other spacecraft.
Questions regarding the amount of space between two objects, the units, or measurement thereof.
276 questions
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…
Questions on systems to uniquely determine position of a point or other geometric element on a manifold such as Euclidean space.
Questions regarding the Milky Way Galaxy, the galaxy that Earth's solar system is in.
232 questions
Questions regarding the history of astronomy, including discoveries and scientists.
217 questions
Questions regarding stars which increase suddenly in energy output due to an explosion which ejected much of its mass.
214 questions
Questions regarding Mars, the fourth planet from the Sun.
213 questions
Questions regarding the action of or an object rotating along an axis.
210 questions
Questions regarding Jupiter, the 5th and largest planet in the Solar System.
209 questions
Questions about relativistic theory of gravity. General relativity describes gravity as a geometrical property of space and time.
208 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.
203 questions
Questions on celestial bodies that orbit planets.
195 questions
Questions regarding the 4-dimensional background structure of our universe.
192 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…
191 questions
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