Lalande 21185 is a red dwarf star approximately 2.5 pc or 8.21 light years from Earth's Solar System, and is the fourth closest known star to the Sun. It has a relatively high velocity and is moving in an orbit perpendicular to the plane of the galaxy. Its closest neighbour is Wolf 359, 1.24 pc or 4.03 ly away. It is also a variable flare star that sometimes increases in brightness. Based on the analysis of astrometric perturbations, this star is thought to possess at least two planets in orbit. In astronomy, an epoch is a moment in time for which celestial coordinates or orbital elements are specified. ... -1... Ursa Major (Ursa Maior in Latin) is a constellation visible throughout the year in the northern hemisphere. ... Right ascension (RA; symbol α: Greek letter alpha) is the astronomical term for one of the two coordinates of a point on the celestial sphere when using the equatorial coordinate system. ... In astronomy, declination (dec) is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. ... The apparent magnitude (m) of a star, planet or other heavenly body is a measure of its apparent brightness; that is, the amount of light received from the object. ... In astronomy, stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral characteristics, and subsequenly refined in terms of other characteristics. ... In astronomy, color index is a simple numerical expression that determines the color of an object. ... In astronomy, color index is a simple numerical expression that determines the color of an object. ... Most stars are of nearly constant luminosity. ... A flare star is a variable star which can undergo unpredictable dramatic increases in brightness for a few minutes or a few hours. ... Astrometry is a part of astronomy and deals with the positions of stars and other celestial bodies, their distances and movements. ... Radial velocity is the velocity of an object in the direction of the line of sight. ... kilometre per second is an SI derived unit of both speed (scalar) and velocity (vector), signified by the symbol km/s or km s-1. ... The proper motion of a star is the motion of the position of the star in the sky (the change in direction in which we see it, as opposed to the radial velocity) after eliminating the improper motions of the stars, which affect their measured coordinates but are not real... A year is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... A year is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... Parallax (Greek: παραλλαγή (parallagé) = alteration) is the change of angular position of two stationary points relative to each other as seen by an observer, due to the motion of said observer. ... personal space, proxemics. ... A light year, abbreviated ly, is the distance light travels in one year: roughly 9. ... The parsec (symbol pc) is a unit of length used in astronomy. ... In astronomy, absolute magnitude is the apparent magnitude, m, an object would have if it were at a standardized distance away. ... Mass is a property of physical objects that, roughly speaking, measures the amount of matter they contain. ... The Sun is the star at the centre of our Solar system. ... RADIUS (Remote Authentication Dial In User Service) is an AAA (authentication, authorization and accounting) protocol for applications such as network access or IP mobility. ... The Sun is the star at the centre of our Solar system. ... // In General Physics In general physics, luminosity (more properly called luminance) is the density of luminous intensity in a given direction. ... The Sun is the star at the centre of our Solar system. ... Temperature is the physical property of a system which underlies the common notions of hot and cold; the material with the higher temperature is said to be hotter. ... The title of this article is incorrect due to technical limitations. ... In astronomy, the metallicity of an object is the proportion of its matter made up of elements other than hydrogen and helium. ... In astronomy, a rotation period is the time an astronomical object takes to complete one revolution around its rotation axis. ... Look up Age on Wiktionary, the free dictionary Age may refer to: The length of time that a person has lived, reckoned from date of birth in most cultures; see also: ageing, for the social, cultural, and economic factors of age and ageing. ... A year is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... In astronomy, many stars are referred to simply by catalogue numbers. ... The Henry Draper Catalogue is an astronomy catalogue with astrometric and spectroscopic data about more than 225,000 stars. ... In astronomy, many stars are referred to simply by catalogue numbers. ... Henry Lee Giclas (born December 9, 1910) is an American astronomer. ... In astronomy, many stars are referred to simply by catalogue numbers. ... In astronomy, many stars are referred to simply by catalogue numbers. ... In astronomy, many stars are referred to simply by catalogue numbers. ... Alexander N. Vyssotsky (born May 23, 1888 in Moscow, Russia; died December 31, 1973 in Winter Park, Florida) was an astronomer. ... The Hipparcos and Tycho Catalogues are the primary products of the European Space Agencys astrometric mission, Hipparcos. ... Red Dwarf is a British science fiction comedy, created and originally written by Rob Grant and Doug Naylor. ... The Pleiades star cluster A star is a massive body of plasma in outer space which is currently or has in the past produced energy through nuclear fusion. ... The parsec (symbol pc) is a unit of length used in astronomy. ... A light year, abbreviated ly, is the distance light travels in one year: roughly 9. ... Earth, also known as the Earth, Terra, and (mostly in the 19th century) Tellus, is the third-closest planet to the Sun. ... Presentation of the solar system (not to scale) The solar system is the retinue of objects gravitationally bound to our Sun. ... The Sun is the star at the centre of our Solar system. ... NGC 4414, a typical spiral galaxy in the constellation Coma Berenices, is about 56,000 light years in diameter and approximately 60 million light years distant. ... The position of Wolf 359 in the Leo constellation; the star is not visible to the naked eye. ... A flare star is a variable star which can undergo unpredictable dramatic increases in brightness for a few minutes or a few hours. ... Astrometry is a part of Astronomy and deals with the positions of stars and other celestial bodies, their distances and movements. ... Perturbation is a term used in astronomy to describe alterations to an objects orbit caused by gravitational interactions with other bodies. ...

This star was discovered by Joseph-Jérôme Lefrançais de Lalande at the Paris Observatory some time before 1801. Joseph Jérôme Lefrançais de Lalande (July 11, 1732 – April 4, 1807) was a French astronomer. ... The Paris Observatory (in French, Observatoire de Paris or Observatoire de Paris-Meudon) is the foremost astronomical observatory of France, and one of the largest astronomical centers in the world. ... 1801 was a common year starting on Thursday (see link for calendar). ...

Lalande 21185 in fiction

• Featured in Civilization II: Test of Time.
• Was renamed Ra in Gregory Benford's novel Across the Sea of Suns.
• In Star Corps by Ian Douglas, one of Lalande 21185's gas giants has an Earth-like moon where an alien race holds humans in slavery, resulting in a force of US Marines being sent in 2148 to free them.

Gregory Benford (born January 30, 1941) is a science fiction author and physicist who is on the faculty of the Department of Physics and Astronomy at the University of California, Irvine. ...

See also

• List of nearest stars

This list of the nearest stars to Earth is ordered by increasing distance out to a maximum of 5 parsecs (16. ...

External links

• SolStation.com: Lalande 21185