In early April, scientists released the first picture ever taken of a black hole. To take the image, the scientists combined information from seven different telescopes, making a telescope as big as the Earth.
Over 100 years ago, Albert Einstein predicted black holes. Since then, scientists have found several ways to prove that black holes exist, but they have never been able to take a picture.
Black holes are so different from our everyday experiences that it can be hard to imagine them.
“Matter” means the stuff that things are made of. Matter can be spread out, or packed tightly. Tightly packed matter is “dense”. If you imagine a bowling ball compared to a Styrofoam ball of the same size, the bowling ball is much heavier because it’s denser.
When we think of gravity, we mainly think of the Earth’s gravity. But actually, everything has gravity and pulls on other things. And the larger and denser something is, the more gravity it has.
A black hole is a place where matter is so dense that the pull of its gravity is very, very strong. The gravity from a black hole is so strong that even light cannot escape it.
So the scientists involved in the Event Horizon Telescope (EHT) project couldn’t actually take a picture of a black hole. Instead, they took a picture of its shadow and the ring of light around the hole called the “event horizon”. That’s the boundary between the hole and the light that is beyond the pull of the hole’s gravity.
The black hole that the scientists took the picture of is massive. It’s about the size of our whole solar system – the system of planets and smaller objects that go around our sun.
But it’s also very far away. The black hole is in a far away galaxy (system of stars) called M87, about 310,000,000,000,000,000,000 miles (500,000,000,000,000,000,000 kilometers) away from Earth.
So how did the scientists get that picture? First off, with lots of work. About 200 scientists in 20 countries worked on the project for almost 10 years.
They used measurements from seven different radio telescopes in different places around the world, including Hawaii, Greenland, and Antarctica. These telescopes recorded radio signals, which can be used to make an image. The scientists used special clocks to make sure the measurements were taken at exactly the same time.
The researchers collected so much information from these telescopes that it could fill the hard drives of about 10,000 laptops. They also had to create computer programs that could sort through and combine all of this information and turn it into a picture.
The picture is proof of Einstein’s ideas that people can see. The EHT project may also teach scientists more about gravity. And the discoveries the EHT team made in order to take the picture can now be used again in new ways.
There is another, smaller black hole in our own galaxy, the Milky Way. EHT has information for this black hole, too, but it has not yet created a picture from it.
This article has been updated to correct an error in the distance given to M87.