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Loading contentPlain-language definitions of astronomy and astrology terms.
In-depth, individual pages in this category.
A self-gravitating sphere of plasma powered by fusion.
A round body that orbits the Sun and has cleared its orbit.
A gravitationally bound system of stars, gas, dust, and dark matter.
An interstellar cloud of gas and dust.
The explosive death of certain stars.
A region of spacetime from which not even light escapes.
The distance light travels in one year — a measure of distance.
The average Earth–Sun distance, about 149.6 million km.
The Sun's apparent yearly path across the sky.
The band of constellations along the ecliptic.
A smaller body passing across the face of a larger one.
In astrology, the zodiac sign rising on the eastern horizon at birth.
The glossary defines the terms used across the site, clearly separating scientific astronomy vocabulary from astrological and mythological terms so the two are never confused.
We continue to expand this category. Upcoming material includes: