Coma (comet) - Wikipedia
The coma is the nebulous envelope around the nucleus of a comet, formed when the comet passes near the Sun in its highly elliptical orbit. As the comet warms, parts of it sublimate; [1] this gives a comet a diffuse appearance when viewed through telescopes and distinguishes it …
Comet - Wikipedia
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 outgassing. This produces an extended, gravitationally unbound atmosphere or coma surrounding the nucleus, and sometimes a tail of gas and dust gas blown out from the coma.
Comets: Facts - NASA Science
A comet warms up as it nears the Sun and develops an atmosphere, or coma. The Sun's heat causes the comet's ices to change to gases so the coma gets larger. The coma may extend hundreds of thousands of kilometers.
Coma | comet | Britannica
…comet nucleus known as a coma. As dust and gas in the coma flow freely into space, the comet forms two tails, one composed of ionized molecules and radicals and one of dust. The word comet comes from the Greek κομητης (kometes), which means …
Comets: Everything you need to know | Space
2023年7月31日 — Comets are defined as icy bodies of frozen gases, rocks and dust left over from the formation of the solar system about 4.6 billion years ago. They orbit the sun in highly elliptical orbits that...
What Is a Comet? | NASA Space Place – NASA Science for Kids
2024年11月8日 — Comets are large objects made of dust and ice that orbit the Sun. Best known for their long, streaming tails, these ancient objects are leftovers from the formation of the solar system 4.6 billion years ago. Comets, such as the comet ISON pictured here, are thought to hold material from the time when the Sun and planets were forming.
Why Comets Are Important - NASA Solar System Exploration
2000年6月7日 — * Comets are small, fragile, irregularly shaped bodies composed of a mixture of grains and frozen gases. They have highly elliptical orbits that repeatedly bring them very close to the Sun and then swing them deeply into space, often beyond the orbit of Pluto.
Parts of a Comet - Science Notes and Projects
2022年1月30日 — The main parts of a comet are the nucleus, coma, hydrogen envelope, dust tail, and ion tail. A comet is a small icy body that orbits the Sun and has a visible atmosphere (coma) and sometimes one or more tails.
Comets - NASA Science
Comets are cosmic snowballs of frozen gases, rock, and dust that orbit the Sun. When frozen, they are the size of a small town. When a comet's orbit brings it close to the Sun, it heats up and spews dust and gases into a giant glowing head larger than most planets. The dust and gases form a tail that stretches away from the Sun for millions of ...
Comet | Definition, Composition, & Facts | Britannica
2024年10月28日 — comet, a small body orbiting the Sun with a substantial fraction of its composition made up of volatile ices. When a comet comes close to the Sun, the ices sublimate (go directly from the solid to the gas phase) and form, along with entrained dust particles, a bright outflowing atmosphere around the comet nucleus known as a coma.