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The apsides refer to the farthest (2) and nearest (3) points reached by an orbiting planetary body (2 and 3) with respect to a primary, or host, body (1). An apsis (from Ancient Greek ἁψίς (hapsís) 'arch, vault'; pl. apsides / ˈ æ p s ɪ ˌ d iː z / AP-sih-deez) [1] [2] is the farthest or nearest point in the orbit of a planetary body about its primary body.
Conversely, aphelion comes from combining "apo," meaning "away from," with "helios." Each term is sometimes called an apsis, which refers to the nearest or farthest point between a celestial body ...
A near-Earth object (NEO) is any small Solar System body orbiting the Sun whose closest approach to the Sun is less than 1.3 times the Earth–Sun distance (astronomical unit, AU). [2] This definition applies to the object's orbit around the Sun, rather than its current position, thus an object with such an orbit is considered an NEO even at ...
The ancient Greek astronomer Hipparchus noted the apsidal precession of the Moon's orbit (as the revolution of the Moon's apogee with a period of approximately 8.85 years); [4] it is corrected for in the Antikythera Mechanism (circa 80 BCE) (with the supposed value of 8.88 years per full cycle, correct to within 0.34% of current measurements). [5]
aphelion The point at which a body orbiting the Earth's Sun is furthest from the Sun. Contrast perihelion. apoapsis The point at which an orbiting body is furthest from its primary. Contrast periapsis. apogee The point at which a body orbiting the Earth (such as the Moon or an artificial satellite) is furthest from the Earth. Contrast perigee.
I miss the definitions of the two kinds of Perihelion times, namely: 1. The perihelion of the earth itself, and 2. The perihelion of the centre of gravity of the earth-moon system. The difference between these two times ("moments")can be as much as 26 hours, depending on the moonphase around January 4.
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Using the Solar System Barycenter as the orbital frame of reference, 2014 FE 72 's extremely elongated orbit (eccentricity = 0.98) has a perihelion of 36.1 AU, an aphelion of ~4,050 AU and a barycentric orbital period of ~92,400 years. [3] The latter values are the largest known for any Solar System body that is not a long-period comet.