To capture this image, the EHT used seven different radio telescopes all around the world in order to use something called interferometry, which combines data from telescopes spread out over a wide distance to essentially create a virtual telescope the size of the distance between the telescopes. The result is a telescope that’s basically the size of Earth. (Among the telescopes used is one at the South Pole, which needed to be retrofitted to make these measurements.)
Then the telescopes have to capture data simultaneously, which means the weather needs to be good in Hawaii and Spain and Chile and the South Pole and other places simultaneously. And when that data is captured, it needs to be brought back to a correlation facility to process it and generate a single data set.
He quotes Dan Marrone, Associate Professor of Astronomy at the University of Arizona:
At the end of that, we had five petabytes of data recorded… it amounts to more than half a ton of hard drives. Five petabytes is a lot of data. It’s equivalent to 5,000 years of MP3 files, or according to one study I read, the entire selfie collection over a lifetime for 40,000 people.
The image you saw, though, isn’t five petabytes in size, it’s a few hundred kilobytes. So our data analysis has to collapse this five petabytes of data into an image that’s more than a billion times smaller. We do that in many steps. The first of those steps is to get [hard drive modules] to our correlators in western Massachusetts and Bonn, Germany. The fastest way to do that is not over the Internet, it’s to put them on planes. There’s no Internet that can compete with petabytes of data on a plane.
This is the ultimate sneakernet.