Glossary term: धूमकेतुको कोमा
Description: धूमकेतु सूर्यको नजिक पुग्दा, हिउँले भरिएको यसको केन्द्रमा रहेका ठोस पदार्थहरूको केही भाग सूर्यको तापमानले गर्दा ग्यासमा परिणत हुन्छ। यो ग्यास, जसमा मुख्यतया पानी भएतापनि यसमा कार्बन मोनोअक्साइड, कार्बन डाइअक्साइड, अमोनिया, मिथेन र मिथानोल जस्ता अन्य रसायनहरू र धुलोका कणहरू पनि केही हदसम्मा समावेश हुन्छन्। यी सबै चीजले न्युक्लियस अथवा केन्द्रलाई धमिलो, गोलाकार बादलजस्तै रूपमा घेर्दछ, जसलाई धूमकेतुको वायुमण्डल वा कोमा भनिन्छ। जति धूमकेतु सूर्यको नजिक पुग्न थाल्छ, सूर्यको पराबैजनी फोटोनहरूद्वारा केन्द्रका धेरै अणुहरू विभाजित हुन्छन्, जसले गर्दा कोमा तात्न थाल्छ र यसको बाहिरी भागहरू खुकुलो हुँदै फैलन थाल्छ। अन्ततः, बाहिरी भागहरू आयनीकृत हुन्छन्, जसले धूमकेतुको आयन पुच्छर बनाउँछ।
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See this term in other languages
Term and definition status: The original definition of this term in English have been approved by a research astronomer and a teacher The translation of this term and its definition is still awaiting approval
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
- अरबिक: هالة المذنب
- जर्मन: Koma (Komet)
- अंग्रेजी: Cometary Coma
- फ्रान्सेली: La chevelure (ou coma) de comète
- ईटालियन: Chioma della cometa
- जापनिज: コマ（彗星の） (external link)
- कोरियाली: 혜성의 코마
- मराठी: धूमकेतूचे वातावरण (कोमा)
- ब्राजिली पुर्तगाली: Coma cometária
- सरल चिनि: 彗发
- प्राचिन चिनि: 彗發
Related Media
Comet C/2020F3 (Neowise) with separate dust and ion gas tails and a green glowing coma, by Dietmar Gutermuth, Germany
Caption: Second place in the 2021 IAU OAE Astrophotography Contest, category Comets.
Comets have a very interesting structure comprising of four main parts: the nucleus, composed of rock, dust and frozen gases, typically spanning a few kilometres, although bigger ones have been observed; a small atmosphere of gas surrounding the nucleus (only present when the comet approaches its closest point to the Sun), called coma; and the two distinctive cometary tails (there is at times third tail). The green colour of the coma is due to carbon and nitrogen present in the coma reacting with the Sun’s ultraviolet radiation. The tail that we are mostly used to observing – dust tail and is composed of micron sized dust particles, the second tail composed of charged particles – ion or gas tail. The tails are released only when the comet approaches the Sun at a distance where the heat and radiation emanating from our star is intense enough to vaporize the frozen gases. The dust tail is curved, while the gas tail is straight and always points away from the Sun as this is carried by the solar wind - flow of charged particles emitted by the Sun. As comets are formed by leftover material, they carry with them important information about the early stages of the Solar System’s formation. This beautiful image shows the comet C/2020 F3 (Neowise), as seen from Germany in July 2020, with three of the four structures clearly visible – coma, gas, and dust tail.
Credit: Dietmar Gutermuth/IAU OAE
License: CC-BY-4.0 Creative Commons Attribution 4.0 International (CC BY 4.0) icons
