Black holes are some of the strangest and most fascinating objects in space. They're extremely dense, with such strong gravitational attraction that not even light can escape their grasp.
A black hole is a region Black holes are points in space that are so dense they create deep gravity sinks. Beyond a certain region, not even light can escape the powerful tug of a black hole's gravity. And anything that ventures too close—be it star, planet, or spacecraft—will be stretched and compressed like putty in a theoretical process aptly known as spaghettification.
There are four types of black holes: stellar, intermediate, supermassive, and miniature. The most commonly known way a black hole forms is by stellar death. As stars reach the ends of their lives, most will inflate, lose mass, and then cool to form white dwarfs. But the largest of these fiery bodies, those at least 10 to 20 times as massive as our own sun, are destined to become either super-dense neutron stars or so-called stellar-mass black holes.
In their final stages, enormous stars go out with a bang in massive explosions known as supernovae. Such a burst flings star matter out into space but leaves behind the stellar core. While the star was alive, nuclear fusion created a constant outward push that balanced the inward pull of gravity from the star's own mass. In the stellar remnants of a supernova, however, there are no longer forces to oppose that gravity, so the star core begins to collapse in on itself.
If its mass collapses into an infinitely small point, a black hole is born. Packing all of that bulk—many times the mass of our own sun—into such a tiny point gives black...n of spacetime where gravity is so strong that nothing – no particles or even electromagnetic radiation such as light – can escape from it. The theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole.
Most black holes form from the remnants of a large star that dies in a supernova explosion. (Smaller stars become dense neutron stars, which are not massive enough to trap light.)
Black holes have made a number of big headlines over the last few years. In 2019, the aptly named Event Horizon Telescope (EHT) managed to capture one on film for the first time. And in May of 2022, the EHT snapped a pic of Sagittarius A*, the supermassive black hole that calls the Milky Way galaxy it's home.
Nearly a month after the Event Horizon Telescope snapped the first image of the black hole at the center of the Milky Way galaxy, astronomers have found a unique object in the universe — a free-floating black hole. Astronomers using gravitational microlensing spotted the phenomenon wandering in deep space.
Gravitational microlensing is a process where astronomers observe the light from a star far behind the black hole, which is momentarily brightened and deflected by an object passing in front of it. The object is the black hole. Astronomers from UC Berkeley estimate that the mass of the invisible compact object is between 1.6 and 4.4 times that of the sun.
The findings are set to be published in the Astrophysical Journal Letters. Astronomers speculate that the object could be a neutron star instead of a black hole. Neutron stars are dense, highly compact objects, but their gravity is balanced by internal neutron pressure, which prevents further collapse of a black hole.
“This is the first free-floating black hole or neutron star discovered through gravitational microlensing. With microlensing, we’re able to probe these lonely, compact objects and weigh them. I think we have opened a new window onto these dark objects, which can’t be seen any other way,” Jessica Lu, a UC Berkeley associate professor of astronomy, and lead author said in a statement.
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