Tulika Bose: This is the 60-second science of Scientific American. I am Tulika Bose.

Today – super massive news from space. The first image of the supermassive black hole in the center of the Milky Way, Sagittarius A *, was released by astronomers this morning.

Here I am talking to Seth Fletcher our editor – in – chief features for Scientific American. He literally wrote a a book about the telescope on the horizon of events, and is our constant expert on all things black holes. So, Seth, what does it actually take to photograph a black hole?

Seth Fletcher: So, I mean, as you know, black holes are technically invisible. They capture everything that falls inside, including the light, everything that passes through the event horizon, which is the border, is captured there forever. He just can never escape.

But super-massive black holes, like Sagittarius A *, are surrounded by glowing obliterated matter that orbits the black hole. Part of it falls into part of it just forms this disk around it and this thing glows, and the black hole because of the way it distorts space, the time around it because of the incredible force of gravity, it casts a shadow against this luminous matter.

And so we actually see that in this picture.

Bose: So we know that astronomers captured this image with a worldwide network of radio observatories called Horizon Event Telescope, or EHT. That’s why you wrote the book. Can you tell me a little bit about that?

Fletcher: People realized a few decades ago that you can collect a certain wavelength of radio light in the microwave. And if you could do it with an Earth-sized radio telescope, you could solve something as small for us as the center of the black hole, the Milky Way, or at least what people thought was there.

The amazing thing about radio astronomy is that there is a technique called interferometry that allows you to combine multiple antennas that are very far apart into one efficient virtual telescope.

Bose: This is the largest high-resolution technique in all of astronomy. What does that actually mean, Seth?

Fletcher: There is only a very limited period of time each year when telescopes in Europe, North America, South America, Antarctica can see the same things in the sky. So they made this complicated schedule for when Sagittarius A *, for example, will be above the horizon and you can see from what telescopes.

They just scan black holes for several nights. They then take all the data to the hard drives. They then physically send it to two supercomputer banks, one in Massachusetts, one in Germany, and then link it all together in one set of data. And then they look for him for general discoveries, where all his telescopes have seen the same thing.

Bose: And why is this such a big deal?

Fletcher: This is just the second black hole we’ve ever seen directly, but it’s much cooler than that. It’s kind of like our personal, super massive black hole. This is at the very center of the Milky Way galaxy.

This is the solution to a mystery that people have been trying to solve for a long time. Now that we can see it, we will see how it changes. We will look at it in the future and this could make possible all kinds of interesting sciences about gravitational space, time, black holes, galaxy formation, who knows what people will be able to prepare.

Bose: Astronomers also say that in the future, by adding more observatories to the EHT, they will even be able to make Sagittarius A * movies. I guess this will look like videos of matter circling the canal before falling into the abyss.

For 60-second science, I’m Tulika Bose.



https://www.scientificamerican.com/podcast/episode/how-astronomers-finally-captured-a-photo-of-our-own-galaxys-black-hole/

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