Known as Proxima Centauri, this faint dwarf star in the southern constellation of Centaurus has none of the trappings of a celestial celebrity.<\/p>\n
Despite being just 4.2 lightyears from the Earth, its average visual magnitude is barely 11, making it so dim that it can only be seen in sizeable telescopes.<\/p>\n
By comparison, if the Sun were at the same distance away as Proxima Centauri it would appear as bright as the Pole Star.<\/p>\n
Read more:<\/strong><\/em><\/p>\n Early measurements showed that Proxima Centauri was about it at around 4.32 lightyears, but by the 1970s it had crept down to 4.28 lightyears.<\/p>\n Hopes of a definitive value were raised in 1989 with the launch of the European Space Agency\u2019s Hipparcos satellite, which set about measuring the positions and distances of 120,000 stars with unprecedented precision.<\/p>\n Its value for Proxima\u2019s distance was certainly impressively precise: 4.223 lightyears give or take around 0.013 lightyears.<\/p>\n But in 1999, a team led by Fritz Benedict of the University of Texas used the Hubble Space Telescope<\/a> to pin down the distance of Proxima even more precisely: 4.243 lightyears (give or take 0.002 lightyears).<\/p>\n This is not only higher than the Hipparcos result \u2013 it also lies outside its most plausible range of values. And it\u2019s still not clear which one is closer to the truth.<\/p>\n This might seem like a petty academic quibble. After all, both values confirm Proxima\u2019s status as the closest star to the Sun, and put 1,000 billion km of space between it and its nearest rival, the binary star<\/a> system Alpha Centauri A\/B.<\/p>\n But pinning down its exact distance has a direct bearing on one of the biggest puzzles surrounding Proxima: is it actually part of the Alpha Centauri A\/B system?<\/p>\n Astronomers have long harboured doubts about Proxima\u2019s status as a free-roving star. By monitoring its position over time, they have been able to work out not only its distance, but also its motion through space.<\/p>\n By as early as 1917 it was clear that Proxima is not only close to Alpha Centauri A\/B, but is also moving at a similar rate through space.<\/p>\n More recent measurements have confirmed this odd coincidence and calculations suggest the chances of getting such similarities by fluke alone are less than one in a million.<\/p>\n Not surprisingly, this has prompted many astronomers to decide that Proxima is not a separate star at all, but part of the Alpha Centauri system.<\/p>\n To this day, many textbooks refer to Proxima as \u2018Alpha Centauri C\u2019.<\/p>\n In 1993, Professor Gerard Gilmore of the University of Cambridge and I showed that Proxima could be travelling through space fast enough to escape the clutches of Alpha.<\/p>\n Frustratingly, however, the measurements of the motion of Proxima and Alpha weren\u2019t quite precise enough to be sure.<\/p>\n![\""An\"](\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2022\/01\/Sun-Proxima-Centauri-difference-size-6a56f08.jpg?quality=90&resize=620%2C464"\" "\\"\"Angular\\"")
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