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 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 about the techniques and practice of observing the night sky.
Questions regarding an object 'falling around' another object, due to a combination of gravity and momentum.
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.
Questions regarding Earth's only natural satellite. For questions about the natural satellites of other planets, use the tag [natural-satellite].
Questions regarding systems of large numbers of stars held together by gravity.
Questions regarding the Sun and objects orbiting it.
Questions regarding the attractive force which exists between any two bodies of matter.
431 questions
Questions related to the physical instruments for astronomical observations.
426 questions
Questions regarding the planet on which humans live; the third planet from the Sun.
418 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.
353 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.
295 questions
Questions regarding all of time and space and its contents.
284 questions
Questions regarding electromagnetic radiation in the visible spectrum.
265 questions
Questions regarding relatively small rocky bodies in an orbit around the Sun.
228 questions
Questions regarding the amount of space between two objects, the units, or measurement thereof.
Questions regarding the Milky Way Galaxy, the galaxy that Earth's solar system is in.
184 questions
Questions about observations performed in the radio frequency range of the electromagnetic spectrum.
181 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…
176 questions
Questions regarding the 4-dimensional background structure of our universe.
172 questions
Questions on systems to uniquely determine position of a point or other geometric element on a manifold such as Euclidean space.
166 questions
Questions regarding stars which increase suddenly in energy output due to an explosion which ejected much of its mass.
Questions regarding the action of or an object rotating along an axis.
155 questions
Questions involving reference frames, time scales, and how they are determined.
153 questions
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.
152 questions
Questions about relativistic theory of gravity. General relativity describes gravity as a geometrical property of space and time.
151 questions
Questions about the increase with time of distance between two distant points in the Universe.
150 questions
Questions regarding a layer of gasses surrounding a celestial object.
150 questions
Questions regarding Jupiter, the 5th and largest planet in the Solar System.
The application of ballistics and celestial mechanics to the practical problems concerning the motion of rockets and other spacecraft.
148 questions
Questions regarding Mars, the fourth planet from the Sun.
144 questions
Questions on celestial bodies that orbit planets.
143 questions
2 3 4 5