Since the mid-1990s, astronomers have found thousands of exoplanets in the Galaxy. But these “almost 5000 exoplanets” are ridiculously few in view of the fact that there should be billions of exoplanets in our Milky Way alone. If one dares to look beyond the Milky Way, it gets even worse.
As for extragalactic planets Jetzer’s team found such evidence back in 2009: an anomaly in a gravitational lensing event in the Andromeda Galaxy. They found that the microlensing event PA-99-N2 from the Andromeda Galaxy could indeed have been such an exoplanet. The Andromeda Galaxy is our cosmically immediately neighboring spiral galaxy – the one with which the Milky Way will one day collide and merge.
In the galaxy M51, also called the Whirlpool Galaxy, 23 million light-years away, the radiation from the X-ray source M51-ULS-1 suddenly disappeared on September 20, 2012 completely during a measurement – for about three hours and then reappeared just as suddenly. Di Stefano and her colleagues see only one plausible explanation for this: a planet orbiting the double star passed in front of the X-ray source as seen from Earth. For all other explanations of the researchers – such as dense dust clouds – a residual X-ray radiation would have remained.
Future investigations will hopefully gain new insights soon. Researchers are definitely in agreement when it comes to the question: Are there exoplanets out there?
But when will we finally be able to see them beyond doubt?
Already first indications for extragalactic exoplanets
