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Near-Earth comets (NECs) are objects in a near-Earth orbit with a tail or coma made up of dust, gas or ionized particles emitted by a solid nucleus. Comet nuclei are typically less dense than asteroids but they pass Earth at higher relative speeds, thus the impact energy of a comet nucleus is slightly larger than that of a similar-sized ...
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 ...
List of NGC objects. List of NGC objects (1–1000) List of NGC objects (1001–2000) List of NGC objects (2001–3000) List of NGC objects (3001–4000) List of NGC objects (4001–5000) List of NGC objects (5001–6000) List of NGC objects (6001–7000) List of NGC objects (7001–7840) List of IC objects; List of Messier objects; List of ...
Most named objects in this list have a diameter of 500 km or more. The Sun, a spectral class G2V main-sequence star; The inner Solar System and the terrestrial planets. 2021 PH27; Mercury. Mercury-crossing minor planets; Venus. Venus-crossing minor planets. 524522 Zoozve, Venus' quasi-satellite; Earth. Moon; Near-Earth asteroids (including ...
The average near-Earth asteroid, such as 2019 VF 5, passes Earth at 18 km/s. The average short-period comet passes Earth at 30 km/s, and the average long-period comet passes Earth at 53 km/s. [10] A retrograde parabolic Oort cloud comet (e=1, i=180°) could pass Earth at 72 km/s when 1 AU from the Sun.
Articles about near-Earth objects, including any small Solar System body whose orbit brings it into proximity with Earth. By convention, a Solar System body is a NEO if its closest approach to the Sun ( perihelion ) is less than 1.3 astronomical units (AU).
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.
The asteroid and comet belts orbit the Sun from the inner rocky planets into outer parts of the Solar System, interstellar space. [ 16 ] [ 17 ] [ 18 ] An astronomical unit , or AU, is the distance from Earth to the Sun, which is approximately 150 billion meters (93 million miles). [ 19 ]