WASHINGTON (AFP) – Astronomers on Tuesday announced they had found the youngest black hole ever found in Earth's cosmic neighbourhood, a discovery offering a rare chance to probe one of the mightiest and strangest forces in the Universe.

The black hole is believed to be a remnant of SN 1979C, a supernova in the galaxy M100, some 50 million light years from Earth, which was spotted by an amateur skygazer in 1979.

The supernova itself was a mega-star some 20 times greater than the Sun that collapsed in upon itself before creating a black hole -- a gravitational force so strong that not even light can escape.

As there is no visual clue to a black hole, the phenomenon was spotted thanks to a steady glow of X-ray radiation detected by US and European orbital observatories from 1995 to 2007.

The discovery will give scientists a grandstand view of how a black hole develops from infancy, NASA said.

It could also unlock knowledge about huge stars explode, which ones give birth to black holes or neutron stars, and how many black holes there may be in our galaxy and elsewhere.

Many new black holes have been discovered in the distant Universe, but they have been spotted thanks to a signature blast of gamma-ray radiation.

SN 1979C, though, is different, as it is closer to Earth and belongs to a class of supernova that is unlike to be associated with a gamma-ray burst.

If so, that will back a common theory about how most black holes are formed.

Finding it was an extraordinary stroke of luck, as normally decades of X-ray observations would be needed to make the confirmation.