asteroid

[ as-tuh-roid ]

noun

1. Astronomy. any of millions of small celestial objects revolving around the sun, often irregularly shaped and having a great range in size, from as small as 6 feet (2 meters) across to about 620 miles (998 kilometers) across: the vast majority of known asteroids exist within the asteroid belt. small solar system body.
2. Zoology. a starfish; an asteroidean.

adjective

1. starlike.

asteroid

/ ˈæstəˌrɔɪd /

noun

1. Also calledminor planetplanetoid any of numerous small celestial bodies that move around the sun mainly between the orbits of Mars and Jupiter. Their diameters range from 930 kilometres (Ceres) to less than one kilometre
2. Also calledasteroideanˌæstəˈrɔɪdɪən any echinoderm of the class Asteroidea; a starfish

adjective

1. of, relating to, or belonging to the class Asteroidea
2. shaped like a star

asteroid

/ ăs′tə-roid′ /

1. Any of numerous small solar system bodies that orbit the Sun primarily in the asteroid belt , a region between the orbits of Mars and Jupiter. Asteroids are intermediate in size between planets and meteoroids with diameters that measure between approximately one hundred and several hundred kilometers. While more than 1,800 asteroids have been cataloged, and as many as a million or more smaller ones may exist, their total mass has been estimated to be less than three percent of the Moon's. Asteroids are thought to be left over from the early formation of the solar system, when planetesimals in a protoplanetary disk were scattered after coming under Jupiter's gravitational influence. The continuing collision of planetesimals that remained between Jupiter and Mars caused many of them to fragment, creating the asteroids that exist today.
2. Also called minor planet planetoid

asteroid

1. A small planet that revolves around the sun . The largest asteroid is only about six hundred miles in diameter . ( See asteroid belt .)

Other Words From

• as·ter·oi·dal adjective
• in·ter·as·ter·oi·dal adjective

Word History and Origins

Origin of asteroid¹

First recorded in 1795–1805; from Greek asteroeidḗs “starry, starlike”; star, -oid

Word History and Origins

Origin of asteroid¹

C19: from Greek asteroeidēs starlike, from astēr a star

Example Sentences

Perhaps, Carr and a few others have imagined, LUCA was the descendent of microbial Martian invaders traveling by asteroid.

From Popular-Science

The analogs in the solar system are all asteroid-sized bodies much less massive than Earth.

From Science News

As he sorts through it, Genge could conceivably come across a speck of 6626 Mattgenge, an 8-kilometer-wide asteroid near Mars named in his honor for his contributions to the study of cosmic dust.

From Quanta Magazine

Although the company has struggled, Bezos has invested to the tune of $1 billion a year in the company and rhapsodizes about a future in which humans live in massive habitats in orbit and mine asteroids.

From Washington Post

NASA’s OSIRIS-REx mission successfully touched down on the asteroid Bennu and collected an overflowing amount of material to bring back to Earth.

From MIT Technology Review

What would it take to carry people to the Moon, or Mars, or an asteroid?

From The Daily Beast

Thinking of longer journeys to Mars or an asteroid would require careful measurement of conditions.

From The Daily Beast

His game lasts until his final ship has either collided with an asteroid or lost a shootout with an enemy saucer.

From The Daily Beast

The Asteroid Belt in the Solar System has many such gaps, created by the gravity of the Sun and Jupiter.

From The Daily Beast

For the record, Deep Impact is about a comet, not an asteroid.

From The Daily Beast

According to Boyle, a non-luminous and non-reflecting asteroid has crashed into the earth's gravitational field.

From Project Gutenberg

In the early afternoon they came to what must be the asteroid's northern pole.

From Project Gutenberg

It always landed on the plain where Parr had first set foot to the asteroid.

From Project Gutenberg

"They were inside this asteroid," decided Parr, half to himself.

From Project Gutenberg

"For getting away, for giving freedom to my only friends on this asteroid," said Parr.

From Project Gutenberg

Related Words

• earth
• globe
• sphere
• world