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 about Saturn, the sixth planet from the Sun.
95 questions
Questions regarding the Hubble Space Telescope, a visible light telescope orbiting Earth.
94 questions
Questions on objects passing through the atmosphere which leave visible wakes of incandescent material.
91 questions
Questions regarding the visible night sky during nighttime from Earth.
91 questions
Questions regarding requests to identify the described object in a photo.
87 questions
Questions related to the instruments used to perform observations in the radio frequency range.
85 questions
Questions about man-made objects orbiting astronomical objects.
85 questions
Questions regarding interactions between galaxies or between major parts of a galaxy.
84 questions
Questions regarding how bright an object appears to be.
83 questions
Questions regarding the as-yet-unknown energy permeating the universe that is responsible for its expansion.
82 questions
Questions regarding two or more stars gravitationally bound to each other
79 questions
Questions about computer programs that assist modeling and observing the dynamics of astronomy.
78 questions
Questions regarding the phenomenon in the early universe characterized by an extreme expansion of space.
77 questions
Questions regarding the bending of light by mass or energy.
76 questions
A collection of ionized gases and dust in interstellar space
76 questions
Questions about patterns formed by group of prominent stars in the night sky.
75 questions
For questions about the various phases on the Moon as observed from the Earth, also known as waxing and waning.
75 questions
Questions regarding an object's movement, or its distance traveled relative to the time taken.
74 questions
Questions regarding the emission of high energy particles or waves through a vacuum or a partice medium.
74 questions
Questions regarding gravitationally bound systems of hundreds to thousands of galaxies as well as interactions between such systems.
74 questions
Questions regarding an object orbiting around another object due to the force of gravity.
73 questions
Questions about the influences of Earth's atmosphere on astronomical observations.
73 questions
Questions regarding neutron stars which emit regular pulses of electromagnetic radiation.
71 questions
Questions regarding the cosmic microwave background, or CMB, the leftover radiation that is taken by many as proof of the Big Bang.
70 questions
Questions about electron degenerate stellar remnants.
69 questions
Questions about Mercury, the first planet from Earth's sun. Also the smallest major planet in the Solar System.
67 questions
Questions about the gas that lays between stars in galaxies.
65 questions
Questions on the ratio of an object's mass with its volume.
64 questions
Questions regarding the physical dimensions of a celestial object.
64 questions
For questions about transits of planets in front of the Sun, as seen from another, more distant planet; for example, the transits of Mercury and Venus which are visible from the Earth.
64 questions
Questions about solar system planets/moons and exoplanets that exhibit similar features to the Earth.
62 questions
Questions regarding the brightness of objects in a defined passband.
62 questions
Questions about quasi-stellar radio sources, active galactic nuclei that are far away and quite old.
62 questions
Questions about the water molecule (composed of two atoms of hydrodgen and one atom of oxygen) and its detection in celestial objects.
59 questions
Questions regarding the former 9th (now dwarf) planet Pluto.
59 questions
Questions regarding the movement of an object at a given speed and direction, often related to the concepts of orbital velocity and escape velocity.
58 questions
1 2
4 5