Thursday, December 2

They detect signs of what could be the first planet discovered outside the Milky Way

  • Paul Rincon
  • BBC News Science Editor

X-ray binary drawing

Image source, ESO / L. Sidewalk


The finding stems from an X-ray binary: a neutron star or a black hole that extracts gas from a companion star.

If the astronomers are correct, this would be the first planet discovered outside of our galaxy.

Until now, about 5,000 “exoplanets” have been identified – defined as worlds that orbit stars other than our Sun – but all of them have been located within our galaxy, the Milky Way.

The possible signal of the planet discovered by NASA’s Chandra X-ray telescope is located in the Messier 51 galaxy, about 28 million light years from the Milky Way.

This finding is based on the so-called transits, in which the passage of a planet in front of a star blocks part of the star’s light and produces a particular decrease in its brightness which is detectable by telescopes.

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