An extragalactic planet, also known as an extragalactic exoplanet, is a planet that is outside the Milky Way. Of all the exoplanets discovered to date, only one is of extragalactic origin. Due to the huge distance of those worlds, they're very hard to detect.
HIP 13044 b
A planet with a mass of at least 1.25 times that of Jupiter has been discovered by the European Southern Observatory (ESO) orbiting a star of extragalactic origin, even though the star now finds itself within our own galaxy. The Jupiter-like planet is particularly unusual, as it is orbiting a star nearing the end of its life and could be about to be engulfed by it, giving tantalizing clues about the fate of our own planetary system in the distant future. The star is called HIP 13044 and it lies about 2000 light-years from Earth in the southern constellation of Fornax.
A microlensing event in the Twin Quasar gravitational lensing system was observed in 1996, by R. E. Schild, in the "A" lobe of the lensed quasar. It is predicted that a 3-Earth-mass planet in the lensing galaxy, YGKOW G1, caused the event. This was the first extragalactic planet candidate announced. This, however, is not a repeatable observation, as it was a one-time chance alignment. This predicted planet lies 4 billion light years away.
Andromeda galaxy planets
A team of scientists has used gravitational microlensing to come up with a tentative detection of an extragalactic exoplanet in Andromeda, our nearest large galactic neighbour. The lensing pattern fits a star with a smaller companion weighing just 6 or 7 times the mass of Jupiter. This suspected planet is the first announced in the Andromeda Galaxy.
- "Planet from another galaxy discovered". ESO Press Release. 18 November 2010. Retrieved 17 November 2011.
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