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.
planet× 411
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.
orbit× 398
Questions regarding an object 'falling around' another object, due to a combination of gravity and momentum.
black-hole× 384
Questions regarding points of extremely high mass density, which creates an extremely strong gravitational field from which light cannot escape.
gravity× 333
Questions regarding the attractive force which exists between any two bodies of matter.
amateur-observing× 220
Questions about the observation of celestial objects by non-professional astronomers.
astrophysics× 219
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.
observation× 215
Questions regarding the action or process of observing a single object carefully to glean information.
distances× 143
Questions regarding the amount of space between two objects, the units, or measurement thereof.
milky-way× 140
Questions regarding the Milky Way Galaxy, the galaxy that Earth's solar system is in.
observational-astronomy× 130
Questions about the techniques and practice of observing the night sky.
space× 119
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.
big-bang-theory× 119
Questions regarding the currently prevalent cosmological model for the origin of the universe.
photography× 118
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…
coordinate× 115
Questions on systems to uniquely determine position of a point or other geometric element on a manifold such as Euclidean space.
supernova× 106
Questions regarding stars which increase suddenly in energy output due to an explosion which ejected much of its mass.
comets× 106
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…
general-relativity× 105
Questions about relativistic theory of gravity. General relativity describes gravity as a geometrical property of space and time.
expansion× 105
Questions about the increase with time of distance between two distant points in the Universe.
radio-astronomy× 103
Questions about observation performed in the radio frequency range of the electromagnetic spectrum (between 10 MHz and 1GHz).
