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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.
As space objects go, comets and meteors are not very big. While a planet like Earth is about 8,000 miles in diameter and a star like our Sun is about 865,000 miles across, the largest asteroid ...
At that time, Uranus, Neptune, nor the asteroid belts have been discovered yet. Orbits of planets are drawn to scale, but the orbits of moons and the size of bodies are not. The term "Solar System" entered the English language by 1704, when John Locke used it to refer to the Sun, planets, and comets. [288]
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.
Astronomers posed over the past decade that dark comets, or objects that resemble asteroids but move like comets, may exist. Now, scientists have found a total of 14 of them.
By 1900 comets were categorized as "periodic", with elliptical orbits, or "non-periodic", one-time with parabolic or hyperbolic orbits. Astronomers believed that planets captured non-periodic comets into elliptical orbits; each planet had a "family" of comets that it captured, with Jupiter's the largest.
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 ...
Periodic comets (also known as short-period comets) are comets with orbital periods of less than 200 years or that have been observed during more than a single perihelion passage [1] (e.g. 153P/Ikeya–Zhang). "Periodic comet" is also sometimes used to mean any comet with a periodic orbit, even if greater than 200 years.