A galaxy is a system of stars, stellar remnants, interstellar gas, dust, dark matter, bound together by gravity. Galaxies, averaging an...

A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called...

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

Venus is the second planet from the Sun and is named after the Roman goddess of love and beauty. As the brightest natural object in...

The International Space Station (ISS) is the largest modularspace station currently in low Earth orbit. It is a multinational...

Astronomers combine mathematical models with observations to develop workable theories of how the Universe came to be. The mathematical...

The James Webb Space Telescope (JWST) is a space telescope designed primarily to conduct infrared astronomy. As the largest optical...

In celestial mechanics, an orbit is the curved trajectory of an object, such as the trajectory of a planet around a star, or of a natural...

The Voyager program is an American scientific program that employs two robotic interstellar probes, Voyager 1 and Voyager 2. They were...

Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, being larger than only Mercury. In English,...

In the early days of the space age, the Apollo astronauts took part in a visionary plan: Bring samples of the lunar surface material,...

The Moon is Earth's only natural satellite. At about one-quarter the diameter of Earth (comparable to the width of Australia), it is the...

Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found...

An astronaut is a person trained, equipped, and deployed by a human spaceflight program to serve as a commander or crew member aboard a...

The National Aeronautics and Space Administration (NASA) is an independent agency of the US federal government responsible for the civil...