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Fomalhaut b is a confirmed,
directly-imaged extrasolar object and candidate planet orbiting the A-type
main-sequence star Fomalhaut, approximately 25 light-years away in the
constellation of Piscis Austrinus. The object was initially announced in 2008
and confirmed as real in 2012 from images taken with the Advanced Camera for
Surveys (ACS) on the Hubble Space Telescope. It has a 2,000-year highly
elliptical orbit and as of May 25, 2013 it is approximately 110 Astronomical
Units (AU – Sun-Earth distances) from its parent star.
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byANDY FLEMING
These days, it is accepted as a scientific fact that we live in a universe teeming with planets orbiting other stars. Indeed, as of 24 September, there are 490 worlds that we know of orbiting stars other than our Sun. Detecting these planets has become a routine voyage of discovery engaging well-tested and accepted methods.
The primary methods include radial velocity (Doppler displacement of spectral lines in the star's light due to the star 'wobbling' as it orbits the common centre of mass of the star and its planetary companion), and the transit method (a dip in starlight as an exoplanet moves across the disc of the star, thus reducing the amount of starlight). Other successful methods include astrometry, where there are minuscule changes over time in a star's precise co-ordinates in the night sky because of its orbit around the stellar system's centre of mass, and microlensing (a bending of light from a distant star due to the gravity of the foreground star and its associated planet – see below).
Finally, of course, there's the most spectacular method, one that will become more important as detectors improve -- that of direct imaging, as in the cases of Fomalhaut b and Beta Pictoris b and associated stellar debris discs, as observed by NASA's Hubble Space Telescope (HST).
