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If the Sun–Neptune distance is scaled to 100 metres (330 ft), then the Sun would be about 3 cm (1.2 in) in diameter (roughly two-thirds the diameter of a golf ball), the giant planets would be all smaller than about 3 mm (0.12 in), and Earth's diameter along with that of the other terrestrial planets would be smaller than a flea (0.3 mm or 0. ...
This glossary of astronomy is a list of definitions of terms and concepts relevant to astronomy and cosmology, their sub-disciplines, and related fields. Astronomy is concerned with the study of celestial objects and phenomena that originate outside the atmosphere of Earth. The field of astronomy features an extensive vocabulary and a ...
However, acceptance of Eris as the tenth planet implicitly demanded a definition of planet that set Pluto as an arbitrary minimum size. Many astronomers, claiming that the definition of planet was of little scientific importance, preferred to recognise Pluto's historical identity as a planet by "grandfathering" it into the planet list. [47]
One of the oldest fields in astronomy, and in all of science, is the measurement of the positions of celestial objects. Historically, accurate knowledge of the positions of the Sun, Moon, planets and stars has been essential in celestial navigation (the use of celestial objects to guide navigation) and in the making of calendars. [67]: 39
The adjectival forms of the names of astronomical bodies are not always easily predictable. Attested adjectival forms of the larger bodies are listed below, along with the two small Martian moons; in some cases they are accompanied by their demonymic equivalents, which denote hypothetical inhabitants of these bodies.
This was an area where only one planet had been expected, and they were much smaller than all other planets; indeed, it was suspected that they might be shards of a larger planet that had broken up. Herschel called them asteroids (from the Greek for "starlike") because even in the largest telescopes they resembled stars, without a resolvable disk.
One of the oldest stars with a multiplanetary system, although it is still more metal-rich than the Sun. None of the known planets is in the habitable zone. [30] 61 Virginis: Virgo: 13 h 18 m 24.31 s: −18° 18′ 40.3″ 4.74: 28: G5V: 0.954: 5531: 8.96: 2 (1) Planet d remains unconfirmed, [31] and a 2021 study found that it was likely a ...
In astronomy, a syzygy (/ ˈ s ɪ z ə dʒ i / SIZ-ə-jee; from Ancient Greek συζυγία (suzugía) 'union, yoking', expressing the sense of σύν (syn-"together") and ζυγ- (zug-"a yoke") [1] [2]) is a roughly straight-line configuration of three or more celestial bodies in a gravitational system.