بلغات أخرى
- الألمانيّة: Koma (Komet)
- الإنجليزيّة: Cometary Coma
- الإسبانيّة: Coma de un cometa
- الفرنسيّة: La chevelure (ou coma) de comète
- الإيطاليّة: Chioma della cometa
- اليابانيّة: コマ（彗星の） (رابط خارجي)
- الكوريّة: 혜성의 코마
- المهاراتية: धूमकेतूचे वातावरण (कोमा)
- النيبالية: धूमकेतुको कोमा
- البرتغاليّة البرازيليّة: Coma cometária
- الصينيّة المبسطة: 彗发
- الصينيّة التقليدية: 彗發
وسائط ذات صلة
Comet C/2020F3 (Neowise) with separate dust and ion gas tails and a green glowing coma, by Dietmar Gutermuth, Germany
الشرح: 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.
المصدر: Dietmar Gutermuth/IAU OAE
License: CC-BY-4.0 المشاع الإبداعي نَسب المُصنَّف 4.0 دولي (CC BY 4.0) أيقونات
An Encounter With Halley's Comet
الشرح: 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.
المصدر: NASA/ESA/Giotto Project
رابط المصدر
License: PD الملكية العامة أيقونات
