Search results
Results from the WOW.Com Content Network
A galaxy is a system of stars, stellar remnants, interstellar gas, dust, and dark matter bound together by gravity. [1] [2] The word is derived from the Greek galaxias (γαλαξίας), literally 'milky', a reference to the Milky Way galaxy that contains the Solar System.
The Milky Way [c] is the galaxy that includes the Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye.
Galaxy (aka HIPASS J1131-31) was hidden behind a relatively fast-moving foreground star (TYC 7215-199-1) and became observable when the star moved aside. [citation needed] Galaxy, relatively nearby, is considered one of the most metal-poor ("extremely metal-poor" (XMP)), least chemically enriched, and seemingly primordial, galaxies known. [10] [11]
Comet Lovejoy and Jupiter, a giant gas planet; The Sun; Sirius A with Sirius B, a white dwarf; the Crab Nebula, a remnant supernova; A black hole (artist concept); Vela Pulsar, a rotating neutron star; M80, a globular cluster, and the Pleiades, an open star cluster; The Whirlpool Galaxy and Abell 2744, a galaxy cluster; Superclusters, galactic ...
[f] Six planets, seven dwarf planets, and other bodies have orbiting natural satellites, which are commonly called 'moons'. The Solar System is constantly flooded by the Sun's charged particles, the solar wind, forming the heliosphere. Around 75–90 astronomical units from the Sun, [g] the solar wind is halted, resulting in the heliopause.
Euler diagram showing the types of bodies orbiting the Sun. The following is a list of Solar System objects by orbit, ordered by increasing distance from the Sun.Most named objects in this list have a diameter of 500 km or more.
Of the Solar System's eight planets and its nine most likely dwarf planets, six planets and seven dwarf planets are known to be orbited by at least 300 natural satellites, or moons. At least 19 of them are large enough to be gravitationally rounded; of these, all are covered by a crust of ice except for Earth's Moon and Jupiter's Io . [ 1 ]
For the giant planets, the "radius" is defined as the distance from the center at which the atmosphere reaches 1 bar of atmospheric pressure. [ 11 ] Because Sedna and 2002 MS 4 have no known moons, directly determining their mass is impossible without sending a probe (estimated to be from 1.7x10 21 to 6.1×10 21 kg for Sedna [ 12 ] ).