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Saturn is named after the Roman god of wealth and agriculture, who was the father of the god Jupiter.Its astronomical symbol has been traced back to the Greek Oxyrhynchus Papyri, where it can be seen to be a Greek kappa-rho ligature with a horizontal stroke, as an abbreviation for Κρονος (), the Greek name for the planet (). [35]
Alan Stern calls these satellite planets, although the term major moon is more common. The smallest natural satellite that is gravitationally rounded is Saturn I Mimas (radius 198.2 ± 0.4 km). This is smaller than the largest natural satellite that is known not to be gravitationally rounded, Neptune VIII Proteus (radius 210 ± 7 km).
The smallest known extrasolar planet that is likely a "gas planet" is Kepler-138d, which has the same mass as Earth but is 60% larger and therefore has a density that indicates a thick gas envelope. [16] A low-mass gas planet can still have a radius resembling that of a gas giant if it has the right temperature. [17]
Saturn – sixth planet from the Sun and the second-largest in the Solar System, after Jupiter. It is a gas giant with an average radius about nine times that of Earth . [ 1 ] [ 2 ] Although only one-eighth the average density of Earth, with its larger volume Saturn is just over 95 times more massive.
A giant planet, sometimes referred to as a jovian planet (Jove being another name for the Roman god Jupiter), is a diverse type of planet much larger than Earth. Giant planets are usually primarily composed of low- boiling point materials ( volatiles ), rather than rock or other solid matter, but massive solid planets can also exist.
The Saturn-mass planet HD 149026 b has only two-thirds of Saturn's radius, so it may have a rock–ice core of 60 Earth masses or more. [39] CoRoT-20b has 4.24 times Jupiter's mass but a radius of only 0.84 that of Jupiter; it may have a metal core of 800 Earth masses if the heavy elements are concentrated in the core, or a core of 300 Earth ...
Terrestrial planets are substantially different from the giant planets, which might not have solid surfaces and are composed mostly of some combination of hydrogen, helium, and water existing in various physical states. Terrestrial planets have a compact, rocky surfaces, and Venus, Earth, and Mars each also has an atmosphere. Their size, radius ...
The planets can be characterized by their force fields: gravity and their magnetic fields, which are studied through geophysics and space physics. Measuring the changes in acceleration experienced by spacecraft as they orbit has allowed fine details of the gravity fields of the planets to be mapped.