What term describes the point at which a celestial object in orbit around the Earth, such as the Moon, makes its closest approach to Earth?
"its mission, Rosetta was crashed into the comet′s surface in 2016. Near-Earth object A near-Earth object (NEO) is any small Solar System body whose orbit brings it to 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). If a NEO's orbit crosses the Earth's and the object is larger than across, it is considered a potentially hazardous object (PHO). Most known PHOs and NEOs are asteroids, but a small fraction are comets. There are over 19,000 known near-Earth asteroids (NEAs), over a"
"in 2000. The term ""perigee-syzygy"" or ""perigee full/new moon"" is preferred in the scientific community. Perigee is the point at which the Moon is closest in its orbit to the Earth, and syzygy is when the Earth, the Moon and the Sun are aligned, which happens at every full or new moon. Astrophysicist Fred Espenak uses Nolle's definition but preferring the label of ""full Moon at perigee"". Wood used the definition of a full or new moon occurring within 24 hours of perigee and also used the label ""perigee-syzygy"". Wood also coined the less used term ""proxigee"" where perigee and"
"Supermoon A supermoon is a full moon or a new moon that approximately coincides with the closest distance that the Moon reaches to Earth in its elliptic orbit, resulting in a slightly larger-than-usual apparent size of the lunar disk as seen from Earth. The technical name is the perigee syzygy of the Earth–Moon–Sun system or more simply full (or new) Moon at perigee. The term ""supermoon"" is astrological in origin and has no precise astronomical definition. The real association of the Moon with both oceanic and crustal tides has led to claims that the supermoon phenomenon may be associated with"
"Appulse Appulse is an astronomical term that refers to the shortest apparent distance between one celestial object and another, as seen from a third body during a given period. The term refers to apparent motion typical of two planets together in the sky, or of the Moon to a star or planet while the Moon orbits Earth, as seen from Earth. An appulse is an apparent phenomenon caused by perspective only; the two objects involved are not near in physical space. An appulse is related to a conjunction, but the definitions differ in detail. While an appulse occurs when the"
"Culmination In observational astronomy, the culmination of a celestial object (the Sun, the Moon, a planet, a star, or a deep-sky object) or constellation is either of two moments when it reaches the observer's meridian on the celestial sphere, on which it appears to move along a circular path over the course of a day, due to Earth's rotation. As viewed from the surface of a terrestrial body, except its geographic poles, a celestial object passes through the meridian twice a day: once at its upper culmination, when it reaches its highest point as viewed from a given location on"
"to the Earth was above the surface. It was captured by two all-sky cameras of the European Fireball Network, which for the first time enabled geometric calculations of the orbit of such a body. On March 18, 2004, LINEAR announced that a asteroid, 2004 FH, would pass the Earth that day at only , about one-tenth the distance to the Moon, and the closest miss ever noticed until then. They estimated that similar-sized asteroids come as close about every two years. On March 31, 2004, two weeks after 2004 FH, set a new record for closest recorded approach above the"
"an ellipse. A circular orbit is a special case, wherein the foci of the ellipse coincide. The point where the orbiting body is closest to Earth is called the perigee, and is called the periapsis (less properly, ""perifocus"" or ""pericentron"") when the orbit is about a body other than Earth. The point where the satellite is farthest from Earth is called the apogee, apoapsis, or sometimes apifocus or apocentron. A line drawn from periapsis to apoapsis is the line-of-apsides. This is the major axis of the ellipse, the line through its longest part. Bodies following closed orbits repeat their paths"
"from the observer's latitude, are described as circumpolar. Culmination In observational astronomy, the culmination of a celestial object (the Sun, the Moon, a planet, a star, or a deep-sky object) or constellation is either of two moments when it reaches the observer's meridian on the celestial sphere, on which it appears to move along a circular path over the course of a day, due to Earth's rotation. As viewed from the surface of a terrestrial body, except its geographic poles, a celestial object passes through the meridian twice a day: once at its upper culmination, when it reaches its highest"
"Pass (spaceflight) A pass, in spaceflight and satellite communications, is the period in which a satellite or other spacecraft is above the local horizon and available for radio communication with a particular ground station, satellite receiver, or relay satellite (or, in some cases, for visual sighting). The beginning of a pass is termed ""acquisition of signal""; the end of a pass is termed ""loss of signal"". The point at which a spacecraft comes closest to a ground observer is the ""time of closest approach"". The timing and duration of passes depends on the characteristics of the orbit a satellite occupies,"
"are close together upon the celestial sphere. In the vast majority of such cases, one of the planets will appear to pass north or south of the other. However, if two celestial bodies attain the same declination at the time of a conjunction in right ascension (or the same ecliptic latitude at a conjunction in ecliptic longitude), the one that is closer to the Earth will pass in front of the other. In such a case, a syzygy takes place. If one object moves into the shadow of another, the event is an eclipse. For example, if the Moon passes"
"for spacecraft. , five near-Earth comets and three near-Earth asteroids have been visited by spacecraft, and probes are en route to two more NEAs. Plans to mine NEAs commercially have been drafted by private companies. The major technical astronomical definition for Near-Earth objects (NEOs) are small Solar System bodies with orbits around the Sun that by definition lie partly between 0.983 (perihelion) and 1.3 (aphelion) astronomical units (AU; Sun–Earth distance) away from the Sun. Thus, NEOs are not necessarily currently near the Earth, but they can potentially approach the Earth relatively closely. However, the term is also used more flexibly"
"terms ""inferior conjunction"" and ""superior conjunction"" are used in particular for the planets Mercury and Venus, which are inferior planets as seen from the Earth. However, this definition can be applied to any pair of planets, as seen from the one farther from the Sun. A planet (or asteroid or comet) is simply said to be in conjunction, when it is in conjunction with the Sun, as seen from the Earth. The Moon is in conjunction with the Sun at New Moon. In a quasiconjunction, a planet in retrograde motion — always either Mercury or Venus, from the point of"
"spacecraft. The International Space Station, the largest artificial satellite of Earth, has a maximum apparent magnitude of –5.9, brighter than the planet Venus. Pass (spaceflight) A pass, in spaceflight and satellite communications, is the period in which a satellite or other spacecraft is above the local horizon and available for radio communication with a particular ground station, satellite receiver, or relay satellite (or, in some cases, for visual sighting). The beginning of a pass is termed ""acquisition of signal""; the end of a pass is termed ""loss of signal"". The point at which a spacecraft comes closest to a ground"
"orbit"" (abbreviated ""AEO"") is a circular areo­synchronous orbit in the Martian equatorial plane about above the surface, any point on which revolves about Mars in the same direction and with the same period as the Martian surface. Areo­stationary orbit is a concept similar to Earth's geo­stationary orbit. The prefix ""areo-"" derives from Ares, the ancient Greek god of war and counterpart to the Roman god Mars, with whom the planet was identified. The modern Greek word for Mars is (). Stationary orbit In celestial mechanics, the term stationary orbit refers to an orbit around a planet or moon where the"
"Elongation (astronomy) In astronomy, a planet's elongation is the angular separation between the Sun and the planet, with Earth as the reference point. The greatest elongation of a given inferior planet occurs when this planet’s position, in its orbital path around the Sun, is at tangent to the observer on Earth. Since an inferior planet is well within the area of Earth's orbit around the Sun, observation of its elongation should not pose that much a challenge (compared to deep-sky objects, for example). When a planet is at its greatest elongation, it appears farthest from the Sun as viewed from"
"the Earth as seen from the Moon changes as the Earth rotates. Central meridian (planets) The central meridian of a celestial body that presents a disc to an observer (such as planet, moon, or star) is the meridian on the body's surface that goes through the centre of the body's disc as seen from the point of view of the observer. The term as generally used in observational astronomy refers to the central meridian of the celestial body as seen by a theoretical observer on Earth for whom the celestial body is at the zenith. An imaginary line is drawn"
"from different viewing positions on the Earth (at one given moment) can appear differently placed against the background of fixed stars. ""Lunar parallax"" (often short for ""lunar horizontal parallax"" or ""lunar equatorial horizontal parallax""), is a special case of (diurnal) parallax: the Moon, being the nearest celestial body, has by far the largest maximum parallax of any celestial body, it can exceed 1 degree. The diagram (above) for stellar parallax can illustrate lunar parallax as well, if the diagram is taken to be scaled right down and slightly modified. Instead of 'near star', read 'Moon', and instead of taking the"
"Earth is approximately which is close to the correct value (0.016710219) (see Earth's orbit). The calculation is correct when perihelion, the date the Earth is closest to the Sun, falls on a solstice. The current perihelion, near January 3, is fairly close to the solstice of December 21 or 22. It took nearly two centuries for the current formulation of Kepler's work to take on its settled form. Voltaire's ""Eléments de la philosophie de Newton"" (Elements of Newton's Philosophy) of 1738 was the first publication to use the terminology of ""laws"". The ""Biographical Encyclopedia of Astronomers"" in its article on"
"degrees apart in the sky at its closest. Conjunction (astronomy) In astronomy, a conjunction occurs when two astronomical objects or spacecraft have either the same right ascension or the same ecliptic longitude, usually as observed from Earth. The astronomical symbol for conjunction is ☌ (in Unicode U+260C) and handwritten . The conjunction symbol is not used in modern astronomy. It continues to be used in astrology. When two objects always appear close to the ecliptic—such as two planets, the Moon and a planet, or the Sun and a planet—this fact implies an apparent close approach between the objects as seen"
"Orbital period The orbital period is the time a given astronomical object takes to complete one orbit around another object, and applies in astronomy usually to planets or asteroids orbiting the Sun, moons orbiting planets, exoplanets orbiting other stars, or binary stars. For objects in the Solar System, this is often referred to as the sidereal period, determined by a 360° revolution of one celestial body around another, e.g. the Earth orbiting the Sun. The name ""sidereal"" is added as it implies that the object returns to the same position relative to the fixed stars projected in the sky. When"
"an Earth-crosser asteroid. Because of its relatively low inclination (7.34°), it is able to come close to each of these planets. Its orbit takes it within 0.021 AU of Mercury's orbit, 0.0368 AU of Venus's orbit, and 0.00989 AU of Earth's orbit. It makes frequent encounters with these inner planets. The last time it came close to Mercury, Venus and Earth was 2010, 1977, and November 12, 2004 respectively. The most recent close approach to Earth was on 11 December 2015 at about 4.2 million kilometers (2.6 million miles, 11 lunar distances). The next visit of the asteroid to Earth's"
"Right ascension Right ascension (abbreviated RA; symbol ) is the angular distance of a particular point measured eastward along the celestial equator from the Sun at the March equinox to the (hour circle of the) point above the earth in question. When paired with declination, these astronomical coordinates specify the direction of a point on the celestial sphere in the equatorial coordinate system. An old term, ""right ascension"" () refers to the ""ascension"", or the point on the celestial equator that rises with any celestial object as seen from Earth's equator, where the celestial equator intersects the horizon at a"
"or within that planet. Owing to mutual gravitational perturbations, the eccentricities of the planetary orbits vary over time. Mercury, the smallest planet in the Solar System, has the most eccentric orbit. At the present epoch, Mars has the next largest eccentricity while the smallest orbital eccentricities are seen with Venus and Neptune. As two objects orbit each other, the periapsis is that point at which the two objects are closest to each other and the apoapsis is that point at which they are the farthest. (More specific terms are used for specific bodies. For example, ""perigee"" and ""apogee"" are the"
"180°. This relationship is referred to as the phase curve. Phase angle (astronomy) Phase angle in astronomical observations is the angle between the light incident onto an observed object and the light reflected from the object. In the context of astronomical observations, this is usually the angle Sun-object-observer. For terrestrial observations, ""Sun–object–Earth"" is often nearly the same thing as ""Sun–object–observer"", since the difference depends on the parallax, which in the case of observations of the Moon can be as much as 1°, or two full Moon diameters. With the development of space travel, as well as in hypothetical observations from"
"a moon of another planet from its central planet, for instance the angular distance of Io from Jupiter. Here we can also talk about ""greatest eastern elongation"" and ""greatest western elongation"". In the case of the moons of Uranus, one often talks about ""greatest northern elongation"" and ""greatest southern elongation"" instead, due to the very high inclination of Uranus' axis of rotation.. Elongation (astronomy) In astronomy, a planet's elongation is the angular separation between the Sun and the planet, with Earth as the reference point. The greatest elongation of a given inferior planet occurs when this planet’s position, in its"
"approach to the Sun) is estimated to have occurred around September 2010. Aphelion (furthest distance from the Sun) is estimated to have occurred around February 2016. , the asteroid is estimated to be from Earth. Perihelion (closest approach to the Sun) may not occur again until August 2021. Orbits computed with only a handful of observations can be unreliable. Short observation arcs can result in computer generated orbits rejecting some data unnecessarily. The 2018 JPL orbit determination shows a semi-major axis of 4.9 AU (albeit with a large 20 AU uncertainty) which would be near Jupiter's orbit. Such an orbit"
"in the WGSN's second bulletin issued in October 2016. The next additions were done on 1 February, 30 June, 5 September and 19 November 2017, and on 6 June 2018. All are included on the current List of IAU-approved Star Names, last updated on 1 June 2018. The star nearest to Earth is typically referred to simply as ""the Sun"" or its equivalent in the language being used (for instance, if two astronomers were speaking French, they would call it ""le Soleil""). However, it is sometimes called by its Latin name, Sol, in science fiction. With the advent of the"
"with an orbit similar to , for comparison, has an absolute magnitude of 16.28 and is notably larger. As a near-Earth object, often comes within ] of Earth. On 29 April 2014, it traveled to 0.0843 AU from Earth, about 33 times further than the Moon. Below is a list of close approaches until 2100 where travels closer than 0.1 AU to Earth. 2013 JX28 Despite being officially classified as a near-Earth object, has a MOID (minimum orbit intersection distance) with Earth of ~0.067 AU, making it highly unlikely to ever hit Earth. For comparison, the Moon orbits Earth at"
"the line of sight to an interior planet (Mercury or Venus) being very close to the solar disk. If the planet passes directly in front of the sun, a solar transit occurs. Solar conjunction Solar conjunction occurs when a planet or other solar system object is on the opposite side of the sun from the Earth. From an Earth reference, the sun will pass between the Earth and the object. Communication with any spacecraft in solar conjunction will be severely limited due to the sun's interference on radio transmissions from the spacecraft. When in reference to Satellite Communications, solar conjunction"
"orbit. The orbital ellipse goes through each of the six Earth images, which are sequentially the perihelion (periapsis — nearest point to the Sun) on anywhere from January 2 to January 5, the point of March equinox on March 19, 20, or 21, the point of June solstice on June 20, 21, or 22, the aphelion (apoapsis — farthest point from the Sun) on anywhere from July 3 to July 5, the September equinox on September 22, 23, or 24, and the December solstice on December 21, 22, or 23. The diagram shows an exaggerated shape of Earth's orbit; the"
"Astronomical object An astronomical object or celestial object is a naturally occurring physical entity, association, or structure that exists in the observable universe. In astronomy, the terms ""object"" and ""body"" are often used interchangeably. However, an astronomical body or celestial body is a single, tightly bound, contiguous entity, while an astronomical or celestial ""object"" is a complex, less cohesively bound structure, which may consist of multiple bodies or even other objects with substructures. 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"
"an observer when it is at its highest point in the sky, compared to when it is on the horizon. Although it appears that the Moon is biggest when it is near the horizon, the opposite is true. This phenomenon is known as the Moon illusion. The reason for the difference in distance is that the distance from the center of the Moon to the center of the Earth is nearly constant throughout the night, but an observer on the surface of Earth is actually 1 Earth radius from the center of Earth. This offset brings them closest to the"
"Quadrature (astronomy) In spherical astronomy, quadrature is the configuration of a celestial object in which its elongation is perpendicular to the direction of the Sun. It is applied especially to the position of a superior planet or the Moon at its first and last quarter phases. As shown in the diagram above, a planet (or other object) can be at the western quadrature (when it is to the west of the Sun when viewed from the Earth) or at the eastern quadrature (when it is to the east of the Sun when viewed from the Earth). Note that an inferior"