Last week the world was presented with the first ever image of a black hole, a supermassive black hole by the name of M87. Recently, scientists have been studying M87, as well as the black hole at the center of our own galaxy, Sagittarius A. While Sagittarius A is much closer, it is dwarfed by the immense size of M87, therefore making M87 the better candidate for the photo.
Here’s a little info about good ole’ M87: first of all, it’s massive – it contains the mass of 6.5 billion suns massive. She thicc, especially compared to Sagittarius A, which only holds about 4.3 million solar masses. M87 lies at the center of an expansive elliptical galaxy, right about 55 million light years away from our own sweet little solar system. So, while it is very far, it is still bright and massive enough to make a good candidate for study.
Image Source: Klemen Vrankar on Unsplash
One may wonder: why is this a big deal? Why did it take so long to get this picture? Well, let me tell you, my friend. To capture the image of M87 a telescope the size of our Earth had to be constructed (which honestly sounds pretty sweet). This means a series of telescopes were set up in six different locations across the globe in an international effort. Together, they made the EHT, or Event Horizon Telescope.
The event horizon is basically the reach of the black hole; if you get to the event horizon, you have no choice but to go in. Black holes suck in any light that falls within their event horizon. Scientists had to figure out a way to photograph something that sucks in light, which is as difficult as it sounds.
Enter: the EHT. *Applause*
Researchers developed the idea that instead of capturing an image of the black hole itself (which is impossible), they would instead get an image of its surrounding event horizon. This is why the picture just looks like an orange ring: it is all of the light that is trapped and being pulled into M87. The dark spot in the center of the ring is the shadow of M87 itself.
Image Source: EHT
The EHT also allows researchers to study Einstein's General Theory of Relativity. I am in no way qualified to explain this theory, so all I will say is this: basically, if an object is massive enough (cough cough M87), it actually bends space-time. Think of a ball sitting in a net. M87 is the ball, the net is space-time. I’m sorry, that’s all I’ve got.
Scientists wanted to make sure the General Theory of Relativity still holds up, as it is rather hard to study. So leading up to capturing the photo of M87, they calculated the size that the event horizon should be in theory. If the image resembled their predictions, Einstein's theory would still hold true. Surprise surprise, it was right on the money. Einstein. Smart guy.
So overall this is really cool and important. Get excited.