Nunki is the σ star in the constellation of Sagittarius

Sigma Sagitarii (σ Sgr / σ Sagittarii) is the second brightest star system in the constellation Sagittarius. It also has the traditional name Nunki. This is a celestial map of the constellation Sagittarius, the Archer. ... This is a celestial map of the constellation Sagittarius, the Archer. ... In astronomy, an epoch is a moment in time for which celestial coordinates or orbital elements are specified. ... Jump to: navigation, search The J2000. ... Jump to: navigation, search Orion is a remarkable constellation, visible from most places on the globe (but not always the whole year long). ... Sagittarius ( , and Latin for Archer) is a constellation of the zodiac, commonly depicted as a centaur drawing a bow. ... 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. ... A light year, abbreviated ly, is the distance light travels in one year: roughly 9. ... Jump to: navigation, search The parsec (symbol pc) is a unit of length used in astronomy. ... 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. ... 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, 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. ... The High Precision Parallax Collecting Satellite of the Hipparcos Space Astrometry Mission was a project of the European Space Agency (ESA) dedicated to the measurement of stellar parallax and the proper motions of stars. ... A star system or stellar system is a group of stars (and possibly smaller bodies such as planets or asteroids) that orbit one another (systems with planetary bodies orbiting stars, are referred to as solar systems or planetary systems). ... Jump to: navigation, search Orion is a remarkable constellation, visible from most places on the globe (but not always the whole year long). ... Sagittarius ( , and Latin for Archer) is a constellation of the zodiac, commonly depicted as a centaur drawing a bow. ...

Nunki has an apparent magnitude of +2.1 and belongs to the spectral classification B3. It has a magnitude +9.5 companion, Sigma Sagitarii B, located 5.2 arcminutes away. 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. ... A minute of arc, arcminute, or MOA is a unit of angular measurement, equal to one sixtieth (1/60) of one degree. ...

Because it is close to the ecliptic, Nunki can be occulted by the Moon and very rarely by planets. The last occultation of Nunki by a planet took place on November 17, 1981, when it was occulted by Venus. The plane of the ecliptic is well seen in this picture from the 1994 lunar prospecting Clementine spacecraft. ... In this July, 1997 still frame captured from video, the bright star Aldebaran has just reappeared on the dark limb of the waning crescent moon in this predawn occultation. ... Jump to: navigation, search Crust composition Oxygen 43% Silicon 21% Aluminium 10% Calcium 9% Iron 9% Magnesium 5% Titanium 2% Nickel 0. ... Jump to: navigation, search A planet in common parlance is a large object in orbit around a star that is not a star itself. ... November 17 is also the name of a Marxist group in Greece. ... Jump to: navigation, search 1981 is a common year starting on Thursday of the Gregorian calendar. ... (*min temperature refers to cloud tops only) Atmospheric characteristics Atmospheric pressure 9. ...