73 relations: Alpha Centauri, AM Canum Venaticorum, Apsis, Asteroid, Astrometry, Astronomical object, Astronomy, Astrophysics, Barycenter, Beta Lyrae, Binary star, Celestial mechanics, Celestial sphere, Center of mass, Ceres (dwarf planet), Conjunction (astronomy), Deimos (moon), Earth, Ecliptic, Elliptic orbit, Epoch (astronomy), Eris (dwarf planet), Exoplanet, Fixed stars, Frame of reference, General relativity, Geostationary orbit, Gravitational constant, Hour, Julian year (astronomy), Jupiter, Kepler's laws of planetary motion, Kilogram, List of periodic comets, Mars, Mercury (planet), Metre, Moon, Natural satellite, Near-Earth object, Neptune, Nodal period, Opposition (planets), Orbit, Orbital node, Orbital resonance, Perihelion and aphelion, Periodic function, Perturbation (astronomy), Planet, ..., Pluto, Precession, Proxima Centauri, Right ascension, Rotation period, Saturn, Semi-major and semi-minor axes, Sidereal time, Sidereal year, Solar System, Solar time, Standard gravitational parameter, Star, Sun, Time standard, Uranus, Venus, 10 Hygiea, 2060 Chiron, 4 Vesta, 50000 Quaoar, 90377 Sedna, 99942 Apophis. Expand index (23 more) » « Shrink index
Alpha Centauri (α Centauri, abbreviated Alf Cen or α Cen) is the star system closest to the Solar System, being from the Sun.
AM Canum Venaticorum is a cataclysmic variable binary star in the constellation of Canes Venatici.
An apsis (ἁψίς; plural apsides, Greek: ἁψῖδες) is an extreme point in the orbit of an object.
Asteroids are minor planets, especially those of the inner Solar System.
Astrometry is the branch of astronomy that involves precise measurements of the positions and movements of stars and other celestial bodies.
An astronomical object or celestial object is a naturally occurring physical entity, association, or structure that exists in the observable universe.
Astronomy (from ἀστρονομία) is a natural science that studies celestial objects and phenomena.
Astrophysics is the branch of astronomy that employs the principles of physics and chemistry "to ascertain the nature of the astronomical objects, rather than their positions or motions in space".
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.
Beta Lyrae (Latinized from β Lyrae, abbreviated Beta Lyr, β Lyr), also named Sheliak, is a binary star system approximately from the Sun in the constellation of Lyra.
A binary star is a star system consisting of two stars orbiting around their common barycenter.
Celestial mechanics is the branch of astronomy that deals with the motions of celestial objects.
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.
Ceres (minor-planet designation: 1 Ceres) is the largest object in the asteroid belt that lies between the orbits of Mars and Jupiter, slightly closer to Mars' orbit.
Christmas is an annual festival commemorating the birth of Jesus Christ,Martindale, Cyril Charles.
The Christmas season, also called the festive season, or the holiday season (mainly in the U.S. and Canada; often simply called the holidays),, is an annually recurring period recognized in many Western and Western-influenced countries that is generally considered to run from late November to early January.
Christmas Eve is the evening or entire day before Christmas Day, the festival commemorating the birth of Jesus.
Christmas traditions vary from country to country.
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.
Deimos (systematic designation: Mars II) is the smaller and outer of the two natural satellites of the planet Mars, the other being Phobos.
Earth is the third planet from the Sun and the only astronomical object known to harbor life.
The ecliptic is the circular path on the celestial sphere that the Sun follows over the course of a year; it is the basis of the ecliptic coordinate system.
In astrodynamics or celestial mechanics, an elliptic orbit or elliptical orbit is a Kepler orbit with an eccentricity of less than 1; this includes the special case of a circular orbit, with eccentricity equal to 0.
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.
Eris (minor-planet designation 136199 Eris) is the most massive and second-largest (by volume) dwarf planet in the known Solar System.
An exoplanet or extrasolar planet is a planet outside our solar system.
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.
In physics, a frame of reference (or reference frame) consists of an abstract coordinate system and the set of physical reference points that uniquely fix (locate and orient) the coordinate system and standardize measurements.
General relativity (GR, also known as the general theory of relativity or GTR) is the geometric theory of gravitation published by Albert Einstein in 1915 and the current description of gravitation in modern physics.
A geostationary orbit, often referred to as a geosynchronous equatorial orbit (GEO), is a circular geosynchronous orbit above Earth's equator and following the direction of Earth's rotation.
The gravitational constant (also known as the "universal gravitational constant", the "Newtonian constant of gravitation", or the "Cavendish gravitational constant"), denoted by the letter, is an empirical physical constant involved in the calculation of gravitational effects in Sir Isaac Newton's law of universal gravitation and in Albert Einstein's general theory of relativity.
An hour (symbol: h; also abbreviated hr.) is a unit of time conventionally reckoned as of a day and scientifically reckoned as 3,599–3,601 seconds, depending on conditions.
In astronomy, a Julian year (symbol: a) is a unit of measurement of time defined as exactly 365.25 days of SI seconds each.
Jupiter is the fifth planet from the Sun and the largest in the Solar System.
In astronomy, Kepler's laws of planetary motion are three scientific laws describing the motion of planets around the Sun.
The kilogram or kilogramme (symbol: kg) is the base unit of mass in the International System of Units (SI), and is defined as being equal to the mass of the International Prototype of the Kilogram (IPK, also known as "Le Grand K" or "Big K"), a cylinder of platinum-iridium alloy stored by the International Bureau of Weights and Measures at Saint-Cloud, France.
Periodic comets (also known as short-period comets) are comets having orbital periods of less than 200 years or that have been observed during more than a single perihelion passage (e.g. 153P/Ikeya–Zhang).
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.
The metre (British spelling and BIPM spelling) or meter (American spelling) (from the French unit mètre, from the Greek noun μέτρον, "measure") is the base unit of length in some metric systems, including the International System of Units (SI).
The Moon is an astronomical body that orbits planet Earth and is Earth's only permanent natural satellite.
A natural satellite or moon is, in the most common usage, an astronomical body that orbits a planet or minor planet (or sometimes another small Solar System body).
A near-Earth object (NEO) is any small Solar System body whose orbit can bring it into proximity with Earth.
Neptune is the eighth and farthest known planet from the Sun in the Solar System.
New Year is the time or day at which a new calendar year begins and the calendar's year count increments by one.
New Year's Day, also called simply New Year's or New Year, is observed on January 1, the first day of the year on the modern Gregorian calendar as well as the Julian calendar.
In the Gregorian calendar, New Year's Eve (also known as Old Year's Day or Saint Sylvester's Day in many countries), the last day of the year, is on 31 December which is the seventh day of Christmastide.
The nodal period (or draconic period) of a satellite is the time interval between successive passages of the satellite through either of its orbital nodes, typically the ascending node.
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.
An orbital node is either of the two points where an orbit intersects a plane of reference to which it is inclined.
In celestial mechanics, an orbital resonance occurs when orbiting bodies exert a regular, periodic gravitational influence on each other, usually because their orbital periods are related by a ratio of small integers.
The perihelion of any orbit of a celestial body about the Sun is the point where the body comes nearest to the Sun.
In mathematics, a periodic function is a function that repeats its values in regular intervals or periods.
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.
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.
Pluto (minor planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of bodies beyond Neptune.
Precession is a change in the orientation of the rotational axis of a rotating body.
Proxima Centauri, or Alpha Centauri C, is a red dwarf, a small low-mass star, about from the Sun in the constellation of Centaurus.
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.
In astronomy, the rotation period of a celestial object is the time that it takes to complete one revolution around its axis of rotation relative to the background stars.
Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter.
In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the widest points of the perimeter.
Sidereal time is a timekeeping system that astronomers use to locate celestial objects.
A sidereal year (from Latin sidus "asterism, star") is the time taken by the Earth to orbit the Sun once with respect to the fixed stars.
The Solar SystemCapitalization of the name varies.
Solar time is a calculation of the passage of time based on the position of the Sun in the sky.
In celestial mechanics, the standard gravitational parameter μ of a celestial body is the product of the gravitational constant G and the mass M of the body.
A star is type of astronomical object consisting of a luminous spheroid of plasma held together by its own gravity.
The Sun is the star at the center of the Solar System.
A time standard is a specification for measuring time: either the rate at which time passes; or points in time; or both.
Uranus is the seventh planet from the Sun.
Venus is the second planet from the Sun, orbiting it every 224.7 Earth days.
10 Hygiea is the fourth-largest asteroid in the Solar System by volume and mass, and it is located in the asteroid belt.
2018 has been designated as the third International Year of the Reef by the International Coral Reef Initiative.
2019 (MMXIX) will be a common year starting on Tuesday of the Gregorian calendar, the 2019th year of the Common Era (CE) and Anno Domini (AD) designations, the 19th year of the 3rd millennium, the 19th year of the 21st century, and the 10th and last year of the 2010s decade.
2060 Chiron, provisional designation, and also known as 95P/Chiron, is a minor planet in the outer Solar System, orbiting the Sun between Saturn and Uranus.
Vesta, minor-planet designation 4 Vesta, is one of the largest objects in the asteroid belt, with a mean diameter of.
50000 Quaoar, provisional designation, is a non-resonant trans-Neptunian object (cubewano) and possibly a dwarf planet in the Kuiper belt, located in the outermost region of the Solar System.
90377 Sedna is a large minor planet in the outer reaches of the Solar System that was,, at a distance of about 86 astronomical units (AU) from the Sun, about three times as far as Neptune.
99942 Apophis (previously known by its provisional designation) is a near-Earth asteroid that caused a brief period of concern in December 2004 because initial observations indicated a probability of up to 2.7% that it would hit Earth on April 13, 2029.
Anomalistic period, Draconic period, Draconitic period, Orbit period, Orbital Period, Orbital periodicity, Period of the orbit, Sidereal period, Siderial period, Sideric, Sinodic period, Synodal, Synodic, Synodic Period, Synodic cycle, Synodic period, Synodic periods, Synodical, Tropical period.