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Among the other dwarf planets, Ceres has no known moons. It is 90 percent certain that Ceres has no moons larger than 1 km in size, assuming that they would have the same albedo as Ceres itself. [6] Eris has one large known moon, Dysnomia. Accurately determining its size is difficult: one indicative estimate of its radius is 350 ± 57.5 km. [7]
NASA's Galileo ' s measurements suggest that large moons can have magnetic fields; it found Ganymede has its own magnetosphere, even though its mass is only 2.5% of Earth's. [18] Alternatively, the moon's atmosphere may be constantly replenished by gases from subsurface sources, as thought by some scientists to be the case with Titan.
The team released a paper of their findings dated 27 April 2007, published in the July 2007 journal Astronomy & Astrophysics. [1] At the time of discovery, it was reported to be the first potentially Earth-like planet in the habitable zone of its star [5] [6] and the smallest-known exoplanet around a main-sequence star, but on 21 April 2009, another planet orbiting Gliese 581, Gliese 581e ...
The Moon is Earth's only natural satellite.It orbits at an average distance of 384,400 km (238,900 mi), about 30 times the diameter of Earth. Tidal forces between Earth and the Moon have synchronized the Moon's orbital period (lunar month) with its rotation period at 29.5 Earth days, causing the same side of the Moon to always face Earth.
The planet was the third planet discovered orbiting the red dwarf Gliese 876, and is the innermost planet in the system. It was the lowest-mass known exoplanet apart from the pulsar planets orbiting PSR B1257+12 at the time of its discovery. Due to its low mass, it can be categorized as a super-Earth.
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 contradictory size and albedo estimates depending on which research paper is being cited.
Triton orbits Neptune in a retrograde orbit—revolving in the opposite direction to the parent planet's rotation—the only large moon in the Solar System to do so. [3] [13] Triton is thought to have once been a dwarf planet from the Kuiper belt, captured into Neptune's orbit by the latter's gravity. [14]
A subsatellite, also known as a submoon or informally a moonmoon, is a "moon of a moon" or a hypothetical natural satellite that orbits the moon of a planet. [ 3 ] It is inferred from the empirical study of natural satellites in the Solar System that subsatellites may be rare, albeit possible, elements of planetary systems .