Search results
Results from the WOW.Com Content Network
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.
No secondary characteristics have been observed around exoplanets. The sub-brown dwarf Cha 110913−773444, which has been described as a rogue planet, is believed to be orbited by a tiny protoplanetary disc, [150] and the sub-brown dwarf OTS 44 was shown to be surrounded by a substantial protoplanetary disk of at least 10 Earth masses. [151]
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).
Jupiter and Saturn have several large moons, such as Io, Europa, Ganymede and Titan, which may have originated from discs around each giant planet in much the same way that the planets formed from the disc around the Sun. [88] [89] [90] This origin is indicated by the large sizes of the moons and their proximity to the planet. These attributes ...
As of 2013, 195 sinuous rilles have been identified on the Moon. [2] Vallis Schröteri in Oceanus Procellarum is the largest sinuous rille, and Rima Hadley is the only one visited by humans, on the Apollo 15 mission. Another prominent example is Rima Herigonius. Arcuate rilles have a smooth curve and are found on the edges of the dark lunar maria.
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.
Artist's conception of a terraformed Venus.The cloud formations are depicted assuming the planet's rotation has not been accelerated. The terraforming of Venus or the terraformation of Venus is the hypothetical process of engineering the global environment of the planet Venus in order to make it suitable for human habitation.
Old theories were unable to explain how their cores could form fast enough to accumulate significant amounts of gas from the quickly disappearing protoplanetary disk. [ 20 ] [ 29 ] The mean lifetime of the disks, which is less than ten million (10 7 ) years, appeared to be shorter than the time necessary for the core formation. [ 17 ]