<P> Alpha Centauri C was discovered in 1915 by the Scottish astronomer Robert Innes, Director of the Union Observatory in Johannesburg, South Africa, who suggested that it be named Proxima Centauri (actually Proxima Centaurus). The name is from Latin, meaning' nearest (star) of Centaurus' . </P> <P> In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars . The WGSN states that in the case of multiple stars the name should be understood to be attributed to the brightest component by visual brightness . The WGSN approved the name Proxima Centauri for Alpha Centauri C on 21 August 2016 and the name Rigil Kentaurus for Alpha Centauri A on 6 November 2016 . They are now both so entered in the IAU Catalog of Star Names . </P> <P> Alpha Centauri is the name given to what appears as a single star to the naked eye and the brightest star in the southern constellation of Centaurus . At − 0.27 apparent visual magnitude (calculated from A and B magnitudes), it is fainter only than Sirius and Canopus . The next - brightest star in the night sky is Arcturus . Alpha Centauri is a multiple - star system, with its two main stars being Alpha Centauri A (α Cen A) and Alpha Centauri B (α Cen B), usually defined to identify them as the different components of the binary α Cen AB . A third companion--Proxima Centauri (or Proxima or α Cen C)--is much further away than the distance between stars A and B, but is still gravitationally associated with the AB system . As viewed from Earth, it is located at an angular separation of 2.2 ° from the two main stars . Proxima Centauri would appear to the naked eye as a separate star from α Cen AB if it were bright enough to be seen without a telescope . Alpha Centauri AB and Proxima Centauri form a visual double star . Together, the three components make a triple star system, referred to by double - star observers as the triple star (or multiple star), α Cen AB - C . </P> <P> Together, the bright visible components of the binary star system are called Alpha Centauri AB (α Cen AB). This "AB" designation denotes the apparent gravitational centre of the main binary system relative to other companion star (s) in any multiple star system . "AB - C" refers to the orbit of Proxima around the central binary, being the distance between the centre of gravity and the outlying companion . Some older references use the confusing and now discontinued designation of A × B. Because the distance between the Sun and Alpha Centauri AB does not differ significantly from either star, gravitationally this binary system is considered as if it were one object . </P>

Can you see alpha centauri without a telescope