The black hole at the center of the Milky Way, Sagittarius A*, is approximately 4 million times the mass of the Sun.
A group of scientists, who have been studying the space giant for 20 years, have just revealed findings that show that back in May, Sagittarius A* was the brightest we've ever seen.
What's more, the reasons behind this are not yet fully understood.
As per Gizmodo, the team of researchers recently observed a flash of infrared radiation that was brighter than had ever been observed in the 20 years of studying the black hole.
While this is nothing to worry about - Sagittarius A* is roughly 26,000 light years away from us - it is an exciting mystery for astronomers to resolve.
“We can see it changing in real time,” Tuan Do, the study’s first author, a research scientist at UCLA, told Gizmodo. “You usually don’t get to do that in astrophysics.”
The researchers observed the black hole for four nights in May using an infrared camera at the Keck Observatory in Hawaii. On May 13, the light emanating from Sagittarius A* mysteriously increased by 75 times in brightness over the course of two hours.
Here's a timelapse of images over 2.5 hr from May from @keckobservatory of the supermassive black hole Sgr A*. The black hole is always variable, but this was the brightest we've seen in the infrared so far. It was probably even brighter before we started observing that night! pic.twitter.com/MwXioZ7twV— Tuan Do (@quantumpenguin) August 11, 2019
According to the paper, published in Astrophysical Journal Letters, statistical models used to understand the black hole may have to be revised in order to account for the unusual variation.
What could be behind the flash?
A star called S0-2 is approaching the black hole. S0-2 may have altered the gas flow into Sagittarius A* causing the brightness, the paper suggests.
In fact, this was the focus of the scientist's initial readings - they were testing Einstein's theory of general relativity by seeing if the black hole would warp the approaching star's light. It did.
Another possibility is that the flash was caused as a result of a delayed reaction to G2, a "dusty object", approaching the black hole.
The team will continue to take observations, preferably multi-wavelength readings, the paper recommends. They hope to find out whether the black hole is more active than usual, or if something else accounts for the unprecedented brightness.