A huge black hole in deep space is stirring after 26 years of slumber.

The black hole, which is part of a system called V404 Cygni, is chowing down on its companion star about 8,000 light-years from Earth. It has been more than 20 years since scientists have seen this kind of extreme activity from these particular bodies in deep space.

In V404 Cygni, the black hole and star that is half as massive as the sun circle one another, while material from the star sloughs off and orbits the black hole, forming a disk around it. As the disk heats up, it starts to shine, and eventually the falling material gets gobbled up by the black hole.

V404 Cygni hasn't shined this brightly since it was observed in 1989, the European Space Agency (ESA) said.

“The behavior of this source is extraordinary at the moment, with repeated bright flashes of light on time scales shorter than an hour, something rarely seen in other black hole systems,” Erik Kuulkers, project scientist for the ESA's Integral space telescope, said in a statement.

“In these moments, it becomes the brightest object in the X-ray sky –- up to fifty times brighter than the Crab Nebula, normally one of the brightest sources in the high-energy sky.”

The V404 Cygni system before the outburst began (left) and after (right). Image: ESA/Integral/IBIS/ISDC

Astronomers also observed the black hole outbursting in 1938 and 1956, well before the 1989 event, and they are learning more about what is causing these peaks of activity.

Scientists hypothesize that the outbursts occur when material from the star reaches a critical mass on the disk of the black hole, which makes the rate at which it absorbs the material change, possibly causing it to glow brilliantly.

The Swift spacecraft, which was designed to quickly detect cosmic explosions, caught sight of the mysterious black hole — which is about 12 times more massive than the sun — coming back to life on June 15, the ESA said.

“Now that this extreme object has woken up again, we are all eager to learn more about the engine that powers the outburst we are observing,” Carlo Ferrigno from the Integral Science Data Center at the University of Geneva, said in a statement.

Astronomers across Earth are helping to observe the outbursting black hole system, the ESA said. After detecting the activity using Swift, the space agency's Integral (short for INTErnational Gamma-Ray Astrophysics Laboratory) has been keeping an eye on V404 Cygni since June 17, and scientists have been using a telescope on La Palma to get high-resolution data about the black hole while it's shining brightly.

V404 Cygni is somewhat special because astronomers have not yet discovered many other black hole binary systems, which have just two objects, in this case a star and a black hole, quite like it.

Learning more about these kinds of systems could lead to a more complete picture of how black holes behave out in the cosmos.