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Examples of astronomical objects include planetary systems, star clusters, nebulae, and galaxies, while asteroids, moons, planets, and stars are astronomical bodies. A comet may be identified as both a body and an object: It is a body when referring to the frozen nucleus of ice and dust, and an object when describing the entire comet with its ...
These lists contain the Sun, the planets, dwarf planets, many of the larger small Solar System bodies (which includes the asteroids), all named natural satellites, and a number of smaller objects of historical or scientific interest, such as comets and near-Earth objects.
This unique spiral galaxy, which is situated 3.2 billion light-years from the Earth, has an extended stream of bright blue knots and diffuse wisps of young stars. [2] It rushes at 3.6 million km/h (1000km/s [2]) through the cluster Abell 2667 and therefore, like a comet, shows a tail, with a length of 600,000 light-years.
Periodic comets usually have elongated elliptical orbits, and usually return to the vicinity of the Sun after a number of decades. The official names of non-periodic comets begin with a "C"; the names of periodic comets begin with "P" or a number followed by "P". Comets that have been lost or disappeared have names with a "D". Comets whose ...
The remaining objects of the Solar System (including the four terrestrial planets, the dwarf planets, moons, asteroids, and comets) together comprise less than 0.002% of the Solar System's total mass. [h] The Sun is composed of roughly 98% hydrogen and helium, [41] as are Jupiter and Saturn.
Comets whose aphelia are near a major planet's orbit are called its "family". [81] Such families are thought to arise from the planet capturing formerly long-period comets into shorter orbits. [82] At the shorter orbital period extreme, Encke's Comet has an orbit that does not reach the orbit of Jupiter, and is known as an Encke-type comet.
first soft landing on a comet (November 2014) Notes: (a) Due to a non-spherical, irregular shape, a comet's x, y, and z axes instead of an (average) diameter are often used to describe its dimensions. (b) Closest approach given in multiples of the comet's (average mean) radius · List ordered in ascending order by a comet's first visit.
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 ]