Absolute magnitude is a measure of the luminosity of a celestial object, on an inverse logarithmic astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent magnitude that the object would have if it were viewed from a distance of exactly 10 parsecs, without extinction of its light due to absorption by interstellar matter and cosmic dust. By hypothetically placing all objects at a standard reference distance from the observer, their luminosities can be directly compared among each other on a magnitude scale.
In astronomy, declination is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle. Declination's angle is measured north or south of the celestial equator, along the hour circle passing through the point in question.
Fornax is a constellation in the southern celestial hemisphere, partly ringed by the celestial river Eridanus. Its name is Latin for furnace. It was named by French astronomer Nicolas Louis de Lacaille in 1756. Fornax is one of the 88 modern constellations.
Taurus is one of the constellations of the zodiac and is located in the northern celestial hemisphere. Taurus is a large and prominent constellation in the Northern Hemisphere's winter sky. It is one of the oldest constellations, dating back to the Early Bronze Age at least, when it marked the location of the Sun during the spring equinox. Its importance to the agricultural calendar influenced various bull figures in the mythologies of Ancient Sumer, Akkad, Assyria, Babylon, Egypt, Greece, and Rome. Its old astronomical symbol is (♉︎), which resembles a bull's head.
In astronomy and navigation, the celestial sphere is an abstract sphere that has an arbitrarily large radius and is concentric to Earth. All objects in the sky can be conceived as being projected upon the inner surface of the celestial sphere, which may be centered on Earth or the observer. If centered on the observer, half of the sphere would resemble a hemispherical screen over the observing location.
Astronomical coordinate systems are organized arrangements for specifying positions of satellites, planets, stars, galaxies, and other celestial objects relative to physical reference points available to a situated observer. Coordinate systems in astronomy can specify an object's position in three-dimensional space or plot merely its direction on a celestial sphere, if the object's distance is unknown or trivial.
The galactic coordinate system is a celestial coordinate system in spherical coordinates, with the Sun as its center, the primary direction aligned with the approximate center of the Milky Way Galaxy, and the fundamental plane parallel to an approximation of the galactic plane but offset to its north. It uses the right-handed convention, meaning that coordinates are positive toward the north and toward the east in the fundamental plane.
Sculptor is a small and faint constellation in the southern sky. It represents a sculptor. It was introduced by Nicolas Louis de Lacaille in the 18th century. He originally named it Apparatus Sculptoris, but the name was later shortened.
The four cardinal directions, or cardinal points, are the four main compass directions: north, east, south, and west, commonly denoted by their initials N, E, S, and W respectively. Relative to north, the directions east, south, and west are at 90 degree intervals in the clockwise direction.
The galactic plane is the plane on which the majority of a disk-shaped galaxy's mass lies. The directions perpendicular to the galactic plane point to the galactic poles. In actual usage, the terms galactic plane and galactic poles usually refer specifically to the plane and poles of the Milky Way, in which Planet Earth is located.
Gaia is a space observatory of the European Space Agency (ESA), launched in 2013 and expected to operate until 2025. The spacecraft is designed for astrometry: measuring the positions, distances and motions of stars with unprecedented precision. The mission aims to construct by far the largest and most precise 3D space catalog ever made, totalling approximately 1 billion astronomical objects, mainly stars, but also planets, comets, asteroids and quasars, among others.
General relativity is a theory of gravitation developed by Albert Einstein between 1907 and 1915. The theory of general relativity says that the observed gravitational effect between masses results from their warping of spacetime.
SS 433 is one of the most exotic star systems observed. It is located in the Milky Way galaxy, and is an eclipsing X-ray binary system, with the primary being a stellar-mass black hole. The spectrum of the secondary companion star suggests that it is a late A-type star. SS 433 is the first discovered microquasar. It is at the centre of the supernova remnant W50.
The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. The term Milky Way is a translation of the Latin via lactea, from the Greek γαλακτικός κύκλος, meaning "milky circle." From Earth, the Milky Way appears as a band because its disk-shaped structure is viewed from within. Galileo Galilei first resolved the band of light into individual stars with his telescope in 1610. Until the early 1920s, most astronomers thought that the Milky Way contained all the stars in the Universe. Following the 1920 Great Debate between the astronomers Harlow Shapley and Heber Curtis, observations by Edwin Hubble showed that the Milky Way is just one of many galaxies.
IC 443 is a galactic supernova remnant (SNR) in the constellation Gemini. On the plane of the sky, it is located near the star Eta Geminorum. Its distance is roughly 5,000 light years from Earth.
NGC 3195 is a planetary nebula located in the southern constellation of Chamaeleon. It is the most southern of all the bright sizable planetary nebula in the sky, and remains concealed from all northern observers. Discovered by Sir John Herschel in 1835, this 11.6 apparent magnitude planetary nebula is slightly oval in shape, with dimensions of 40×35 arc seconds, and can be seen visually in telescopic apertures of 10.5 centimetres (4.1 in) at low magnifications.
A galactic quadrant, or quadrant of the Galaxy, is one of four circular sectors in the division of the Milky Way Galaxy.
This glossary of astronomy is a list of definitions of terms and concepts relevant to astronomy and cosmology, their sub-disciplines, and related fields. Astronomy is concerned with the study of celestial objects and phenomena that originate outside the atmosphere of Earth. The field of astronomy features an extensive vocabulary and a significant amount of jargon.
The barycentric celestial reference system (BCRS) is a coordinate system used in astrometry to specify the location and motions of astronomical objects. It was created in 2000 by the International Astronomical Union (IAU) to be the global standard reference system for objects located outside the gravitational vicinity of Earth: planets, moons, and other Solar System bodies, stars and other objects in the Milky Way galaxy, and extra-galactic objects.
In astronomy, Gaia16aye is a gravitational microlensing event of the star 2MASS 19400112+3007533 by a dimmer binary star system. The source star 2MASS 19400112+3007533 is a magnitude 14.5 star in Cygnus. It was closely observed during a set of brightening events caused by gravitational microlensing in 2016. The Gaia16aye event was first noticed by the Gaia space mission via an alert on August 9, 2016. The unusual characteristics of the event led to an immediate massive follow-up campaign by tens of professional and amateur observers over the next 500 days, during which 5 brightening events were closely observed. The star brightened up to two and a half magnitudes in each microlensing event over its baseline brightness.
