91 relations: Aberration of light, Analytical dynamics, Angular momentum, Aquarius (constellation), Aries (constellation), Astrological sign, Astronomical nutation, Astronomical unit, Axial tilt, Barycenter, Cancer (constellation), Capricornus, Cartesian coordinate system, Celestial coordinate system, Celestial equator, Celestial pole, Celestial sphere, Center of mass, Cetus, Conjunction (astronomy), Constellation, Coplanarity, December solstice, Diurnal motion, Earth, Earth radius, Earth's orbit, Earth's rotation, Eclipse, Ecliptic coordinate system, Epoch (astronomy), Equation of time, Equator, Equatorial coordinate system, Equinox, Figure of the Earth, Fixed stars, Formation and evolution of the Solar System, Fundamental ephemeris, Fundamental plane (spherical coordinates), Gemini (constellation), Gregorian calendar, Invariable plane, Jet Propulsion Laboratory Development Ephemeris, Julian day, June solstice, Kilometre, Leo (constellation), Libra (constellation), March equinox, ..., Mars, Mercury (planet), Minute and second of arc, Moon, Newcomb's Tables of the Sun, Nutation, Observational astronomy, Ophiuchus, Opposition (planets), Orbit, Orbit of the Moon, Orbital inclination, Orbital node, Orbital plane (astronomy), Orbital pole, Perpendicular, Perturbation (astronomy), Pisces (constellation), Plane (geometry), Planet, Precession, Protoplanetary disk, Right ascension, Sagittarius (constellation), Scorpius, September equinox, Sidereal time, Solar System, Solstice, Spherical coordinate system, Summation, Sun, Sunrise, Sunset, Taurus (constellation), Terrestrial Time, Tropical year, Venus, Virgo (constellation), Year, Zodiac. Expand index (41 more) » « Shrink index
The aberration of light (also referred to as astronomical aberration, stellar aberration, or velocity aberration) is an astronomical phenomenon which produces an apparent motion of celestial objects about their true positions, dependent on the velocity of the observer.
In classical mechanics, analytical dynamics, or more briefly dynamics, is concerned with the relationship between motion of bodies and its causes, namely the forces acting on the bodies and the properties of the bodies, particularly mass and moment of inertia.
In physics, angular momentum (rarely, moment of momentum or rotational momentum) is the rotational equivalent of linear momentum.
Aquarius is a constellation of the zodiac, situated between Capricornus and Pisces.
Aries is one of the constellations of the zodiac.
In Western astrology, astrological signs are the twelve 30° sectors of the ecliptic, starting at the vernal equinox (one of the intersections of the ecliptic with the celestial equator), also known as the First Point of Aries.
Astronomical nutation is a phenomenon which causes the orientation of the axis of rotation of a spinning astronomical object to vary over time.
The astronomical unit (symbol: au, ua, or AU) is a unit of length, roughly the distance from Earth to the Sun.
In astronomy, axial tilt, also known as obliquity, is the angle between an object's rotational axis and its orbital axis, or, equivalently, the angle between its equatorial plane and orbital plane.
The barycenter (or barycentre; from the Ancient Greek βαρύς heavy + κέντρον centre) is the center of mass of two or more bodies that are orbiting each other, which is the point around which they both orbit.
Cancer is one of the twelve constellations of the zodiac.
Capricornus is one of the constellations of the zodiac.
A Cartesian coordinate system is a coordinate system that specifies each point uniquely in a plane by a pair of numerical coordinates, which are the signed distances to the point from two fixed perpendicular directed lines, measured in the same unit of length.
In astronomy, a celestial coordinate system is a system for specifying positions of celestial objects: satellites, planets, stars, galaxies, and so on.
The celestial equator is the great circle of the imaginary celestial sphere on the same plane as the equator of Earth.
The north and south celestial poles are the two imaginary points in the sky where the Earth's axis of rotation, indefinitely extended, intersects the celestial sphere.
In astronomy and navigation, the celestial sphere is an abstract sphere with an arbitrarily large radius concentric to Earth.
In physics, the center of mass of a distribution of mass in space is the unique point where the weighted relative position of the distributed mass sums to zero, or the point where if a force is applied it moves in the direction of the force without rotating.
Cetus is a constellation.
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.
A constellation is a group of stars that are considered to form imaginary outlines or meaningful patterns on the celestial sphere, typically representing animals, mythological people or gods, mythological creatures, or manufactured devices.
In geometry, a set of points in space are coplanar if there exists a geometric plane that contains them all.
The December solstice, also known as the southern solstice, is the solstice that occurs each December, typically between the 20th and the 22nd day of the month according to the Gregorian calendar.
Diurnal motion (lit, from dies, lit. "day") is an astronomical term referring to the apparent daily motion of stars around Earth, or more precisely around the two celestial poles.
Earth is the third planet from the Sun and the only astronomical object known to harbor life.
Earth radius is the approximate distance from Earth's center to its surface, about.
Earth's orbit is the trajectory along which Earth travels around the Sun.
Earth's rotation is the rotation of Planet Earth around its own axis.
An eclipse is an astronomical event that occurs when an astronomical object is temporarily obscured, either by passing into the shadow of another body or by having another body pass between it and the viewer.
The ecliptic coordinate system is a celestial coordinate system commonly used for representing the apparent positions and orbits of Solar System objects.
In astronomy, an epoch is a moment in time used as a reference point for some time-varying astronomical quantity, such as the celestial coordinates or elliptical orbital elements of a celestial body, because these are subject to perturbations and vary with time.
The equation of time describes the discrepancy between two kinds of solar time.
An equator of a rotating spheroid (such as a planet) is its zeroth circle of latitude (parallel).
The equatorial coordinate system is a celestial coordinate system widely used to specify the positions of celestial objects.
An equinox is commonly regarded as the moment the plane (extended indefinitely in all directions) of Earth's equator passes through the center of the Sun, which occurs twice each year, around 20 March and 22-23 September.
The figure of the Earth is the size and shape of the Earth in geodesy.
The fixed stars (stellae fixae) comprise the background of astronomical objects that appear to not move relative to each other in the night sky compared to the foreground of Solar System objects that do.
The formation and evolution of the Solar System began 4.6 billion years ago with the gravitational collapse of a small part of a giant molecular cloud.
A fundamental ephemeris of the Solar System is a model of the objects of the system in space, with all of their positions and motions accurately represented.
The fundamental plane in a spherical coordinate system is a plane of reference that divides the sphere into two hemispheres.
Gemini is one of the constellations of the zodiac.
The Gregorian calendar is the most widely used civil calendar in the world.
The invariable plane of a planetary system, also called Laplace's invariable plane, is the plane passing through its barycenter (center of mass) perpendicular to its angular momentum vector.
The name Jet Propulsion Laboratory Development Ephemeris (followed by a number), the abbreviation JPL DE(number), or just DE(number) designates one of a series of models of the Solar System produced at the Jet Propulsion Laboratory in Pasadena, California, primarily for purposes of spacecraft navigation and astronomy.
Julian day is the continuous count of days since the beginning of the Julian Period and is used primarily by astronomers.
The June solstice, also known as the northern solstice, is the solstice on the Earth that occurs each June falling on the 20th to 22nd according to the Gregorian calendar.
The kilometre (International spelling as used by the International Bureau of Weights and Measures; SI symbol: km; or) or kilometer (American spelling) is a unit of length in the metric system, equal to one thousand metres (kilo- being the SI prefix for). It is now the measurement unit used officially for expressing distances between geographical places on land in most of the world; notable exceptions are the United States and the road network of the United Kingdom where the statute mile is the official unit used.
Leo is one of the constellations of the zodiac, lying between Cancer the crab to the west and Virgo the maiden to the east.
Libra is a constellation of the zodiac.
The March equinox or Northward equinox is the equinox on the Earth when the subsolar point appears to leave the southern hemisphere and cross the celestial equator, heading northward as seen from Earth.
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System after Mercury.
Mercury is the smallest and innermost planet in the Solar System.
A minute of arc, arcminute (arcmin), arc minute, or minute arc is a unit of angular measurement equal to of one degree.
The Moon is an astronomical body that orbits planet Earth and is Earth's only permanent natural satellite.
Newcomb's Tables of the Sun is the short title and running head of a work by the American astronomer and mathematician Simon Newcomb entitled "Tables of the Motion of the Earth on its Axis and Around the Sun" on pages 1–169 of "Tables of the Four Inner Planets" (1895), volume VI of the serial publication Astronomical Papers Prepared for the Use of the American Ephemeris and Nautical Almanac.
Nutation (from Latin nūtātiō, "nodding, swaying") is a rocking, swaying, or nodding motion in the axis of rotation of a largely axially symmetric object, such as a gyroscope, planet, or bullet in flight, or as an intended behavior of a mechanism.
Observational astronomy is a division of astronomy that is concerned with recording data about the observable universe, in contrast with theoretical astronomy, which is mainly concerned with calculating the measurable implications of physical models.
Ophiuchus is a large constellation straddling the celestial equator.
In positional astronomy, two astronomical objects are said to be in opposition when they are on opposite sides of the celestial sphere, as observed from a given body (usually Earth).
In physics, an orbit is the gravitationally curved trajectory of an object, such as the trajectory of a planet around a star or a natural satellite around a planet.
The Moon orbits Earth in the prograde direction and completes one revolution relative to the stars in about 27.322 days (a sidereal month) and one revolution relative to the Sun in about 29.530 days (a synodic month).
Orbital inclination measures the tilt of an object's orbit around a celestial body.
An orbital node is either of the two points where an orbit intersects a plane of reference to which it is inclined.
The orbital plane of a revolving body is the geometric plane on which its orbit lies.
An orbital pole is either point at the ends of an imaginary line segment that runs through the center of an orbit (of a revolving body like a planet) and is perpendicular to the orbital plane.
In elementary geometry, the property of being perpendicular (perpendicularity) is the relationship between two lines which meet at a right angle (90 degrees).
In astronomy, perturbation is the complex motion of a massive body subject to forces other than the gravitational attraction of a single other massive body.
Pisces is a constellation of the zodiac.
In mathematics, a plane is a flat, two-dimensional surface that extends infinitely far.
A planet is an astronomical body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.
Precession is a change in the orientation of the rotational axis of a rotating body.
A protoplanetary disk is a rotating circumstellar disk of dense gas and dust surrounding a young newly formed star, a T Tauri star, or Herbig Ae/Be star.
Right ascension (abbreviated RA; symbol) is the angular distance measured only eastward along the celestial equator from the Sun at the March equinox to the (hour circle of the) point above the earth in question.
Sagittarius is one of the constellations of the zodiac.
Scorpius is one of the constellations of the zodiac.
The September equinox (or Southward equinox) is the moment when the Sun appears to cross the celestial equator, heading southward.
Sidereal time is a timekeeping system that astronomers use to locate celestial objects.
The Solar SystemCapitalization of the name varies.
A solstice is an event occurring when the Sun appears to reach its most northerly or southerly excursion relative to the celestial equator on the celestial sphere.
In mathematics, a spherical coordinate system is a coordinate system for three-dimensional space where the position of a point is specified by three numbers: the radial distance of that point from a fixed origin, its polar angle measured from a fixed zenith direction, and the azimuth angle of its orthogonal projection on a reference plane that passes through the origin and is orthogonal to the zenith, measured from a fixed reference direction on that plane.
In mathematics, summation (capital Greek sigma symbol: ∑) is the addition of a sequence of numbers; the result is their sum or total.
The Sun is the star at the center of the Solar System.
Sunrise or sun up is the instant at which the upper edge of the Sun appears over the horizon in the morning.
Sunset or sundown is the daily disappearance of the Sun below the horizon as a result of Earth's rotation.
Taurus (Latin for "the Bull") is one of the constellations of the zodiac, which means it is crossed by the plane of the ecliptic.
Terrestrial Time (TT) is a modern astronomical time standard defined by the International Astronomical Union, primarily for time-measurements of astronomical observations made from the surface of Earth.
A tropical year (also known as a solar year) is the time that the Sun takes to return to the same position in the cycle of seasons, as seen from Earth; for example, the time from vernal equinox to vernal equinox, or from summer solstice to summer solstice.
Venus is the second planet from the Sun, orbiting it every 224.7 Earth days.
Virgo is one of the constellations of the zodiac.
A year is the orbital period of the Earth moving in its orbit around the Sun.
The zodiac is an area of the sky that extends approximately 8° north or south (as measured in celestial latitude) of the ecliptic, the apparent path of the Sun across the celestial sphere over the course of the year.