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Massive Explosion In Earth's Nearest Galaxy
A massive explosion in our nearest galaxy may have been caused by two stars colliding.
A sudden burst of gamma-rays in the Andromeda Galaxy was detected by a Nasa satellite on Wednesday morning.
There are various different types of gamma-ray emissions, and it is unclear whether it was specifically a gamma ray burst (GRB).
If it was, it may have been caused by the collision of two neutron stars.
It would be significant given that Andromeda is 2.5 million light years away - the previous nearest GRB took place 2.6 billion light years away.
By observing how the light fades over the next 24-48 hours, astronomers should be able to tell what type of gamma-ray emission it was.
Nasa's Swift Burst Alert telescope watches the skies for gamma-ray bursts and sends their locations back to stations on the ground.
It observes around 90 gamma ray events every year, but usually from much further away.