Hooray! Astronomers have finally been able to take an actual image of a black hole!
M87, a galaxy 55 million light years away, is a gigantic elliptical galaxy bright enough to be observed in your backyard on a clear night.
The inner region of the galaxy contains mostly hot gas, but most importantly a supermassive black hole, the most massive one we’ve measured so far!
How Was The Image Taken?
8 Telescopes that make up the Event Horizon Telescope (EHT) were used to take this image, using Very Long Baseline Interferometry (VLBI) to create an Earth-sized telescope with incredibly high resolution. Customising and connecting telescopes for VLBI takes years to execute, but EHT and CHANDRA succeeded! The image was taken in 2017, but was published on the 10th of April 2019.
The image couldn’t be taken like a normal photo. The telescopes used were radio telescopes, and produced raw data which needed to be analysed using multiple algorithms.
Katie Bouman, doctor in electrical engineering and computer science, started writing the algorithms as a graduate. Eventually she lead a team to complete the algorithm, taking over three years to finish.
An amazing achievement and huge leap forward in science!
A Little Bit About M87
M87 is a galaxy rich in globular clusters. The amount was estimated to be 12’000, roughly 60 x the clusters in the Milky Way. Clusters in M87 gradually increase in size the further from the center they are. In fact, nearly a hundred of these clusters were recently discovered to be dwarf galaxies!
Near the black hole lies ionised gas, forming a bright halo. The supermassive black hole heats the gas as it falls into the center. It’s estimated that 5.4 x 10^26 kg of gas fall into the black hole every day (or 90 M ⊕).
Observing M87 from your backyard
M87 lies in the Virgo Constellation. You can use a planisphere to determine if you can see Virgo, but on average it is visible in the North from early February to late May, as is M87. Now is the perfect time to go and observe for yourself!
M87 isn’t in the southern hemisphere, but those who live near the equator may be able to see the galaxy. Any further, and it’s completely out of view, I’m afraid to say.
Learn more about the Event Horizon Telescope here.