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However, Pluto is also protected by its 2:3 orbital resonance with Neptune: for every two orbits that Pluto makes around the Sun, Neptune makes three, in a frame of reference that rotates at the rate that Pluto's perihelion precesses (about 0.97 × 10 −4 degrees per year [90]). Each cycle lasts about 495 years.
The Kuiper belt (/ ˈkaɪpər / KY-pər) [ 1 ] is a circumstellar disc in the outer Solar System, extending from the orbit of Neptune at 30 astronomical units (AU) to approximately 50 AU from the Sun. [ 2 ] It is similar to the asteroid belt, but is far larger—20 times as wide and 20–200 times as massive. [ 3 ][ 4 ] Like the asteroid belt ...
Apparent retrograde motion is the apparent motion of a planet in a direction opposite to that of other bodies within its system, as observed from a particular vantage point. Direct motion or prograde motion is motion in the same direction as other bodies. While the terms direct and prograde are equivalent in this context, the former is the ...
The great conjunction of 2020 was the closest since 1623 [12] [2] and eighth closest of the first three millennia AD, with a minimum separation between the two planets of 6.1 arcminutes. [2] This great conjunction was also the most easily visible close conjunction since 1226 (as the previous close conjunctions in 1563 and 1623 were closer to ...
In astronomy, a conjunction occurs when two astronomical objects or spacecraft appear to be close to each other in the sky. This means they have either the same right ascension or the same ecliptic longitude, usually as observed from Earth. [1][2] When two objects always appear close to the ecliptic —such as two planets, the Moon and a planet ...
Pluto is the only trans-Neptunian object with a known atmosphere. [7] Its closest analog is the atmosphere of Triton, although in some aspects it resembles even the atmosphere of Mars. [8] [9] The atmosphere of Pluto has been studied since the 1980s by way of earth-based observation of occultations of stars by Pluto [10] [11] and spectroscopy. [12]
Charon, the largest of Pluto's moons, is sometimes described as part of a binary system with Pluto, as the two bodies orbit a barycenter of gravity above their surfaces (i.e. they appear to "orbit each other"). Orcus (30.3–48.1 AU), is in the same 2:3 orbital resonance with Neptune as Pluto, and is the largest such object after Pluto itself ...
New Horizons was based largely on Stern's work since Pluto 350 and involved most of the team from Pluto Kuiper Express. [31] The New Horizons proposal was one of five that were officially submitted to NASA. It was later selected as one of two finalists to be subject to a three-month concept study in June 2001.