Glossary term: Comet Nucleus
Description: A comet nucleus is the core of a comet. This is a solid object, similar to a dirty snowball, made with ice and rocky, dusty particles. Far from the Sun the nucleus is the sole component of the comet. Closer to the Sun a comet's nucleus is heated due to sunlight. This causes the surface ice to sublimate. The sublimated ice and the dust embedded in it are ejected and surround the nucleus as a coma with a tail pointing away from the Sun.
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Term and definition status: This term and its definition have been approved by a research astronomer and a teacher
The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".
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In Other Languages
- Arabic: نواة المذنب
- German: Kometenkern
- Spanish: Núcleo del cometa
- French: Noyau de la comète
- Italian: Nucleo della cometa
- Korean: 혜성핵
- Brazilian Portuguese: Núcleo cometário
- Simplified Chinese: 彗核
- Traditional Chinese: 彗核
Related Media
Comet 67P/Churyumov-Gerasimenko
Caption: Comet 67P/Churyumov–Gerasimenko's nucleus is a "dirty snowball" made of a mixture of frozen materials and dust. It is shaped like two large lobes: one 4.1 km × 3.3 km × 1.8 km, the other 2.6 km × 2.3 km × 1.8 km. These lobes are connected by a small bridge. When a cometary nucleus such as this nears the Sun its frozen, icy material is heated, turning into gas. This, combined with the embedded dust, provide the material for the comet's characteristic coma and tail.
Credit: ESA/Rosetta/NAVCAM
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License: CC-BY-SA-3.0-IGO Creative Commons Attribution-ShareAlike 3.0 IGO icons
An Encounter With Halley's Comet
Caption: This image shows the solid core, or nucleus, of Halley’s Comet, captured in 1986 by the European Space Agency spacecraft Giotto during its flyby of the comet in the inner Solar System. The nucleus appears irregular and potato-shaped, measuring roughly 15 kilometers (about 9 miles) across, and is composed of a mixture of ice, dust, and rock. Unlike the glowing fuzzy cloud (coma) and long tail that make comets visible from Earth, the nucleus itself is dark and difficult to see until a spacecraft passes close enough to take detailed images.
Halley’s Comet is one of the best-known comets because it returns to the inner Solar System approximately every 76 years, allowing generations of astronomers to observe it repeatedly. The material that is released from the nucleus as the comet warms near the Sun forms a glowing coma and long tails of gas and dust, and over many returns leaves trails of debris that produce meteor showers on Earth, such as the Eta Aquarids in May and the Orionids in October.
Credit: NASA/ESA/Giotto Project
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License: PD Public Domain icons
