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Currently most of the objects of mass between 10 9 kg to 10 12 kg (less than 1000 teragrams (Tg)) listed here are near-Earth asteroids (NEAs). The Aten asteroid 1994 WR12 has less mass than the Great Pyramid of Giza, 5.9 × 10 9 kg. For more about very small objects in the Solar System, see meteoroid, micrometeoroid, cosmic dust, and ...
A dwarf planet is a small planetary-mass object that is in direct orbit around the Sun, massive enough to be gravitationally rounded, but insufficient to achieve orbital dominance like the eight classical planets of the Solar System. The prototypical dwarf planet is Pluto, which for decades was regarded as a planet before the "dwarf" concept ...
The number of dwarf planets in the Solar System is unknown. Estimates have run as high as 200 in the Kuiper belt [1] and over 10,000 in the region beyond. [2] However, consideration of the surprisingly low densities of many large trans-Neptunian objects, as well as spectroscopic analysis of their surfaces, suggests that the number of dwarf planets may be much lower, perhaps only nine among ...
Size (left) and distance (right) of a few well-known galaxies put to scale. The following is a list of notable galaxies.. There are about 51 galaxies in the Local Group (see list of nearest galaxies for a complete list), on the order of 100,000 in the Local Supercluster, and an estimated 100 billion in all of the observable universe.
The mean apparent magnitude is 0.23 while the standard deviation of 1.78 is the largest of any planet. The mean apparent magnitude at superior conjunction is −1.89 while that at inferior conjunction is +5.93. [16] Observation of Mercury is complicated by its proximity to the Sun, as it is lost in the Sun's glare for much of the time.
720,000 km/h (450,000 mi/h) [ 10] Orbital period. ~230 million years [ 10] The Solar System[ d] is the gravitationally bound system of the Sun and the objects that orbit it. [ 11] It was formed about 4.6 billion years ago when a dense region of a molecular cloud collapsed, forming the Sun and a protoplanetary disc.
Giant planet. The four giant planets of the Solar System: ( top) Jupiter and Saturn ( gas giants) ( bottom) Uranus and Neptune ( ice giants) Shown in order from the Sun and in true color. Sizes are not to scale. A giant planet, sometimes referred to as a jovian planet ( Jove being another name for the Roman god Jupiter ), is a diverse type of ...
A terrestrial planet, telluric planet, or rocky planet, is a planet that is composed primarily of silicate, rocks or metals. Within the Solar System, the terrestrial planets accepted by the IAU are the inner planets closest to the Sun: Mercury, Venus, Earth and Mars. Among astronomers who use the geophysical definition of a planet, two or three ...