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  2. Comet - Wikipedia

    en.wikipedia.org/wiki/Comet

    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.

  3. Comet nucleus - Wikipedia

    en.wikipedia.org/wiki/Comet_nucleus

    Comet nuclei, at ~1 km to at times tens of kilometers, could not be resolved by telescopes. Even current giant telescopes would give just a few pixels on target, assuming nuclei were not obscured by comae when near Earth. An understanding of the nucleus, versus the phenomenon of the coma, had to be deduced, from multiple lines of evidence.

  4. Observational history of comets - Wikipedia

    en.wikipedia.org/.../Observational_history_of_comets

    He theorized that the Earth was the center of the universe, which was surrounded by various other planets and stars. The universe or better known as the heavens filled the void above the terrestrial atmosphere with a fifth element called "Aether." Aristotle believed that comets were shooting stars that evolved into something much different.

  5. Comet tail - Wikipedia

    en.wikipedia.org/wiki/Comet_tail

    A comet tail and coma are visible features of a comet when they are illuminated by the Sun and may become visible from Earth when a comet passes through the inner Solar System. As a comet approaches the inner Solar System, solar radiation causes the volatile materials within the comet to vaporize and stream out of the nucleus , carrying dust ...

  6. History of the center of the Universe - Wikipedia

    en.wikipedia.org/wiki/History_of_the_center_of...

    A mandala creates a world center within the boundaries of its two-dimensional space analogous to that created in three-dimensional space by a shrine. [6] In medieval times some Christians thought of Jerusalem as the center of the world (Latin: umbilicus mundi, Greek: Omphalos), and was so represented in the so-called T and O maps. Byzantine ...

  7. Glossary of astronomy - Wikipedia

    en.wikipedia.org/wiki/Glossary_of_astronomy

    The precise geometric center of the Earth's Sun, i.e. the arithmetic mean position of all points within the approximate spheroid that is the shape of the Sun. heliocentric With reference to, or pertaining to, the geometric center of the Earth's Sun; [14] centered upon the Sun, e.g. a heliocentric orbit. heliopause heliosphere

  8. Nasa finds icy ‘super-Earth’ that could be home to alien life

    www.aol.com/nasa-finds-icy-super-earth-163011865...

    Liquid water is believed to be one of the key requirements for life, at least as it exists on Earth. From their research, scientists speculate that as much as 20 per cent of the world’s mass is ...

  9. Scattered disc - Wikipedia

    en.wikipedia.org/wiki/Scattered_disc

    Because of its unstable nature, astronomers now consider the scattered disc to be the place of origin for most periodic comets in the Solar System, with the centaurs, a population of icy bodies between Jupiter and Neptune, being the intermediate stage in an object's migration from the disc to the inner Solar System. [4]