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The Milky Way is the galaxy that includes the Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the...

The Sun is the star at the center of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion...

The International Space Station (ISS) is a large space station assembled and maintained in low Earth orbit by a collaboration of five space agencies and...

Venus is the second planet from the Sun. It is a terrestrial planet and is the closest in mass and size to its orbital neighbour Earth. Venus is notable...

Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter. It is a gas giant with an average radius of about nine-and-a-half...

A star is a luminous spheroid of plasma held together by self-gravity. The nearest star to Earth is the Sun. Many other stars are visible to the naked...

The zodiac is a belt-shaped region of the sky that extends approximately 8° north and south (as measured in celestial latitude) of the ecliptic, the apparent...

The Wow! signal was a strong narrowband radio signal detected on August 15, 1977, by Ohio State University's Big Ear radio telescope in the United States...

A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby obscuring the view of the Sun from a small part of Earth, totally or partially...

The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to...

The Big Bang was the initiation of the continuing expansion of the universe from a state of high density and temperature (its central singularity). It...

Titan is the largest moon of Saturn and the second-largest in the Solar System. It is the only moon known to have an atmosphere denser than the Earth's...

A constellation is an area on the celestial sphere in which a group of visible stars forms a perceived pattern or outline, typically representing an animal...

The Space Shuttle is a retired, partially reusable low Earth orbital spacecraft system operated from 1981 to 2011 by the U.S. National Aeronautics and...

Halley's Comet, Comet Halley, or sometimes simply Halley, officially designated 1P/Halley, is the only known short-period comet that is consistently visible...

In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is...

Starlink is a satellite internet constellation operated by Starlink Services, LLC, a wholly-owned subsidiary of American aerospace company SpaceX, providing...

Unsolved problem in physics: What is dark matter? How was it generated? (more unsolved problems in physics) In astronomy, dark matter is a hypothetical...

A satellite or artificial satellite is an object, typically a spacecraft, placed into orbit around a celestial body. Satellites have a variety of uses...

A meteoroid (/ˈmiːtiərɔɪd/ MEE-tee-ə-royd) is a small rocky or metallic body in outer space. Meteoroids are distinguished as objects significantly smaller...