All galaxies have supermassive black holes at their centre, but they are only called quasars when matter gets too close, heats up to millions of degrees and then blasts out enormous amounts of radiation, or jets.

ASTRONOMERS have discovered two massive black holes are on course to collide causing a titanic blast capable of destroying an entire galaxy.

But before you break out your end-of-the-world survival packs, fear not, the galaxy is not ours. (Phew?!).

Researchers using data from NASA’s Galaxy Evolution Explorer (GALEX) and NASA’s Hubble Space Telescope have discovered that not only do these astronomical phenomenon exist, but they are so close to each other, they are considered to be the “tightest orbiting pair” detected so far.

The distance between them has been estimated at about one million light years away or the diameter of our solar system.

Researchers also predict that when they do the merge, which is estimated to be within a million years, the collision will have the power of 100 million supernovae (that’s superpowerful).

Black hole mergers are considered to be the most violent events in the Universe.

When they finally meet, they converge in a type of “death spiral,” and are predicted to send out ripples known as gravitational waves, a theory devised by Albert Einstein 100 years ago.

Scientists at the California Institute of Pasadena who are trying to gauge a better understanding of how galaxies and black holes merge, first found the pair earlier this year after finding an unusual light signal coming from the centre of a galaxy, named PG 1302-102.

Using telescopes at the Catalina Real-Time Transient Survey, they found the varying signal was most likely generated by the motion of two black holes, while they swing around each other every five years.

The black holes themselves don’t give off light, but the material surrounding them does, NASA reported.

The study was published in this month’s edition of the journal, Nature.

According to the authors, as the black holes spin faster the material gives off more light. And the brighter the light, the closer it is to Earth.

“It’s as if a 60-Watt light bulb suddenly appears to be 100 Watts,” Daniel D’Orazio, lead author of the study from Columbia University told NASA.

“As the black hole light speeds away from us, it appears as a dimmer 20-Watt bulb.”

The researchers were able to prove their theory from observations made by both the GALEX and Hubble telescopes.

“We were lucky to have GALEX data to look through,” said co-author David Schiminovich of Columbia University in New York.

“We went back into the GALEX archives and found that the object just happened to have been observed six times.”

The researchers now hope others will be able to use what they have found to find even closer-knit merging black holes.

“We are strengthening our ideas of what’s going on in this system and starting to understand it better,” said Zoltan Haiman, another co-author from Columbia University.