This list covers 29 astronomy words, starting with “Van Allen Belt” and ending with “Viking Program.” You’ll find planets, stars, constellations, spacecraft missions, and key concepts that describe how our universe works. Students, stargazers, and curious readers use terms like these to make sense of what they read about space, from news on distant galaxies to the latest planetary missions.
Astronomy words are the specialized terms scientists and enthusiasts use to describe objects, events, and ideas in space. They range from everyday names like “Venus” to technical concepts like “velocity dispersion.” One fun example is “Vulcan,” a planet astronomers once believed orbited near Mercury until Einstein’s theory of relativity proved it didn’t exist.
Below you’ll find the table with Word, Definition, and Description.
Word: the astronomy term itself, listed alphabetically so you can quickly scan or search for the one you need.
Definition: a short, plain-language explanation that tells you exactly what the word means without extra detail.
Description: additional context that helps you understand why the word matters, including examples, history, or how it’s used in astronomy today.
Astronomy words
| Word | Definition |
|---|---|
| Van Allen Belt | A region of trapped charged particles around Earth |
| Variable Star | A star whose brightness changes noticeably over time |
| Vega | A bright star in the constellation Lyra |
| Vela | A southern constellation representing a ship’s sails |
| Vela Pulsar | A rapidly spinning neutron star in the Vela constellation |
| Velocity Dispersion | The statistical spread of speeds within a group of objects |
| Venus | The second planet from the Sun |
| Vernal Equinox | The moment when day and night are roughly equal in length |
| Very Large Array | A radio telescope observatory in New Mexico |
| Very Large Telescope | An optical telescope facility in Chile |
| Vesta | One of the largest bodies in the asteroid belt |
| Virgo | A large zodiac constellation |
| Virgo Cluster | A cluster of roughly 1,300 galaxies |
| Virgo Supercluster | A vast collection of galaxy clusters and groups |
| Virial Theorem | A physics relation linking a system’s kinetic and potential energy |
| Visible Light | Electromagnetic radiation detectable by the human eye |
| Visual Binary | A pair of stars visible as separate points through a telescope |
| Visual Magnitude | A measure of how bright a celestial object appears |
| Void | A vast, nearly empty region of space between galaxy filaments |
| Volatile | A chemical element or compound that vaporizes at low temperature |
| Volcanism | The eruption of molten material from a planetary body |
| Von Karman Line | The conventional boundary between Earth’s atmosphere and space |
| Voyager Program | NASA’s twin robotic probes launched in 1977 |
| Vulcan | A hypothetical planet once thought to orbit inside Mercury’s orbit |
| Vulcanoid Asteroid | A hypothetical asteroid orbiting between the Sun and Mercury |
| V838 Monocerotis | A red variable star known for a massive outburst |
| Vacuum Energy | The energy inherently present in empty space itself |
| Very Long Baseline Interferometry | A technique linking widely separated radio telescopes together |
| Viking Program | NASA’s pair of Mars orbiter-lander missions launched in 1975 |
Descriptions
Van Allen Belt
A doughnut-shaped zone of energetic particles held in place by Earth’s magnetic field, discovered in 1958.
Variable Star
These stars fluctuate due to internal pulsations or eclipses, and astronomers use them as reliable tools for measuring cosmic distances.
Vega
One of the brightest stars in the night sky and a former northern pole star, often used as a brightness standard in astronomy.
Vela
Home to the famous Vela Pulsar and the vast Vela Supernova Remnant left behind by an ancient stellar explosion.
Vela Pulsar
One of the brightest pulsars known, formed roughly 10,000 years ago when a massive star collapsed and exploded.
Velocity Dispersion
Astronomers measure how fast stars move relative to each other within a cluster or galaxy to estimate its total mass.
Venus
A scorching, cloud-covered world often called Earth’s twin for its similar size, though a thick atmosphere traps intense heat at its surface.
Vernal Equinox
Marks the Sun crossing the celestial equator heading north, signaling the start of astronomical spring in the Northern Hemisphere.
Very Large Array
A network of 27 linked radio antennas that study everything from forming stars to distant black holes.
Very Large Telescope
One of the world’s most powerful ground-based observatories, made up of four giant telescopes used for cutting-edge research.
Vesta
A bright, differentiated protoplanet visited by NASA’s Dawn spacecraft, notable for a massive impact crater near its south pole.
Virgo
Home to the Virgo Cluster of galaxies, making it a key landmark for mapping the nearby universe.
Virgo Cluster
The nearest large galaxy cluster to us, forming the gravitational core of the larger Virgo Supercluster.
Virgo Supercluster
Contains the Local Group, which itself holds our own Milky Way galaxy, making it part of our cosmic address.
Virial Theorem
Astronomers use it to estimate the mass of galaxy clusters and star systems that are in gravitational balance.
Visible Light
The narrow slice of the spectrum that optical telescopes rely on, sitting between infrared and ultraviolet light.
Visual Binary
Two gravitationally bound stars close enough to Earth that their orbital dance around each other can be directly observed.
Visual Magnitude
A logarithmic scale astronomers use to rank stars and other objects by their apparent brightness as seen from Earth.
Void
Enormous bubble-like gaps in the cosmic web that contain very few galaxies compared to the dense structures around them.
Volatile
Substances like water, carbon dioxide, and methane that easily turn to gas, shaping the surfaces and atmospheres of planets, moons, and comets.
Volcanism
A geological process seen throughout the solar system, from Earth’s volcanoes to the dramatic sulfur eruptions on Jupiter’s moon Io.
Von Karman Line
Set at roughly 100 kilometers altitude, it’s the commonly used marker for where a flight becomes a spaceflight.
Voyager Program
Voyager 1 and 2 toured the outer planets and are now the most distant human-made objects, currently traveling through interstellar space.
Vulcan
Proposed in the 1800s to explain odd quirks in Mercury’s path, later shown unnecessary once Einstein’s relativity explained the mystery.
Vulcanoid Asteroid
A theorized population of small, sun-scorched rocky bodies that has never been confirmed to actually exist.
V838 Monocerotis
Famous for a dramatic 2002 flare that produced a spectacular expanding “light echo” captured in stunning detail by Hubble.
Vacuum Energy
A theoretical concept tied to dark energy, thought to be a driving force behind the universe’s accelerating expansion.
Very Long Baseline Interferometry
Combines signals from telescopes across entire continents to produce extremely sharp images, famously used to capture the first picture of a black hole.
Viking Program
Viking 1 and 2 were the first American spacecraft to successfully land on and photograph the surface of Mars.