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Mercury, the smallest and innermost planet, has no moons, or at least none that can be detected to a diameter of 1.6 km (1.0 mi). [2] For a very short time in 1974, Mercury was thought to have a moon. Venus also has no moons, [3] though reports of a moon around Venus have circulated since the 17th century.
There has not yet been an orbiter around Uranus or Neptune for long-term study of their moons. For the small outer irregular moons of Uranus, such as Sycorax, which were not discovered by the Voyager 2 flyby, even different NASA web pages, such as the National Space Science Data Center [6] and JPL Solar System Dynamics, [5] give somewhat ...
Of the inner planets, Mercury and Venus have no natural satellites; Earth has one large natural satellite, known as the Moon; and Mars has two tiny natural satellites, Phobos and Deimos. The giant planets have extensive systems of natural satellites, including half a dozen comparable in size to Earth's Moon: the four Galilean moons , Saturn's ...
The moons of the trans-Neptunian objects (other than Charon) have not been included, because they appear to follow the normal situation for TNOs rather than the moons of Saturn and Uranus, and become solid at a larger size (900–1000 km diameter, rather than 400 km as for the moons of Saturn and Uranus).
Venus is the second planet from the Sun.It is a terrestrial planet and is the closest in mass and size to its orbital neighbour Earth.Venus has by far the densest atmosphere of the terrestrial planets, composed mostly of carbon dioxide with a thick, global sulfuric acid cloud cover.
The object was seen by many other astronomers over a large period of time: by James Short in 1740, [4] by Andreas Mayer in 1759, [4] by Louis Lagrange in 1761, [5] another eighteen observations in 1761, including one in which a small spot was seen following Venus while the planet was in a transit across the Sun, eight observations in 1764, and ...
No vulcanoids, asteroids between the orbit of Mercury and the Sun, have been discovered. [132] [133] As of 2024, one asteroid has been discovered to orbit completely within Venus's orbit, 594913 ꞌAylóꞌchaxnim. [134] Venus-crossing asteroids are those that cross the orbit of Venus. There are 2,809 as of 2015. [135]
Several different types of small moons have been called moonlets: A belt of objects embedded in a planetary ring, especially around Saturn, such as those in the A Ring, S/2009 S 1 in the B Ring ("propeller" moonlets), [2] [3] and those in the F Ring [4] Occasionally asteroid moons, such as those of 87 Sylvia [5]