The Event Horizon Telescope Collaboration, called EHT, is a global network of telescopes that captured the first photograph of a black hole.
In May 2022, scientists revealed the historic first image of the supermassive black hole at the center of our galaxy — Sagitarrius A*.
There are now two images of black holes.
This is the black hole that was observed in 2017 by a network of telescopes around the world known as the Event Horizon Telescope, which together acted as a giant radio telescope the size of the Earth. Two years later, with much fanfare, the international EHT team announced they'd produced the first image of M87.
Because we're missing much of the signal, “instead of seeing a crystal clear photo, you see something that's a little foggy … a little blurred.” The image helps reveal more about the black hole's event horizon — the closest point to which anything can approach the black hole without being sucked in.
But, the problem is that we can't get up close to see for ourselves. Why, we can't even take photographs of anything that takes place inside a black hole — if light cannot escape their immense gravity, then nothing can be snapped by a camera.
A telescope the size of the Earth
Black holes are so named because they themselves cannot be seen—they are regions of space where gravity is so powerful that not even light can escape. The bright “donuts” of light in the famous images are actually light and matter being ripped apart and chewed up by the black holes.
The nearest known black hole is Gaia BH1, which was discovered in September 2022 by a team led by Kareem El-Badry. Gaia BH1 is 1,560 light-years away from Earth in the direction of the constellation Ophiuchus.
It was captured by the Event Horizon Telescope, an array which linked together eight existing radio observatories across the planet to form a single “Earth-sized” virtual telescope. Although we cannot see the event horizon itself, we can see light bent by the powerful gravity of the black hole.
Black holes have two parts. There is the event horizon, which you can think of as the surface, though it's simply the point where the gravity gets too strong for anything to escape. And then, at the center, is the singularity. That's the word we use to describe a point that is infinitely small and infinitely dense.
While researchers have never found a wormhole in our universe, scientists often see wormholes described in the solutions to important physics equations. Most prominently, the solutions to the equations behind Einstein's theory of space-time and general relativity include wormholes.
Therefore, our galaxy must harbor some 100 million stellar-mass black holes. Most of these are invisible to us, and only about a dozen have been identified.
Astronomers have discovered a black hole coming towards Earth. Astronomers have discovered a black hole coming towards Earth. Before you get too alarmed, just know that we aren't actually in danger — however, that doesn't make the news any less unsettling.
Near a black hole, the slowing of time is extreme. From the viewpoint of an observer outside the black hole, time stops. For example, an object falling into the hole would appear frozen in time at the edge of the hole. Inside a black hole is where the real mystery lies.
Black holes are dark, dense regions in space where the pull of gravity is so strong that nothing can escape. Not even light can get out of these regions. That is why we cannot see black holes—they are invisible to our eyes. Because nothing can get out of black holes, physicists struggle understanding these objects.
Beyond the event horizon lies a truly minuscule point called a singularity, where gravity is so intense that it infinitely curves space-time itself. This is where the laws of physics, as we know them, break down, meaning all theories about what lies beyond are just speculation.
We might be the product of another, older universe. Call it our mother universe. The seed this mother universe forged inside a black hole may have had its big bounce 13.8 billion years ago, and even though our universe has been rapidly expanding ever since, we could still be hidden behind a black hole's event horizon.
You can't see it (see paragraph 2 above). Every black hole has a minimum distance from it where, to escape its gravity, you'd need to move at the speed of light. Nothing can do this, which is why black holes are black (and why they're holes, for that matter). This distance is called the event horizon.
A black hole forms when the mass of an object, like a star, suddenly collapses down to a tiny volume. A small object with a large mass causes a gaping dent in space-time. This enormous warp creates a gravitational field so strong that nothing—not even light—can escape from it.
For most space objects, we use light-years to describe their distance. A light-year is the distance light travels in one Earth year. One light-year is about 6 trillion miles (9 trillion km). That is a 6 with 12 zeros behind it!
The two black holes lie just 1,560 and 3,800 light-years from our planet, respectively. Astronomers have discovered two new black holes that are the closest ones to Earth known, and also represent something that astronomers have never seen before.
The nearest black hole candidate is roughly 1.3 million times as far away as Voyager 1. The probe would have to travel more than 50 million years (a lot more, actually, as it is still slowing down due to the Sun's gravity; it hasn't quite left our neighborhood yet) to get there.
We are in absolutely no danger from black holes. They're a bit like tigers – it's a bad idea to stick your head in their mouth, but you're probably not going to meet one on your way to the shops. Unlike tigers, black holes don't hunt. They're not roaming around space eating stars and planets.
At present, we don't have spacecraft that could get us anywhere near a black hole. But, even leaving that small detail aside, attempting to travel into the past using a black hole might be the last thing you ever do.
But creating a black hole with even a microscopic event horizon would require billions of times more energy than the LHC is able to produce. And even if it could produce such a black hole, that object would quickly lose energy and dissipate in the blink of an eye.