5 Facts About the First Ever Image of a Black Hole

Last week we witnessed an incredible first: the first ever image taken of a black hole. If you turned on a computer, opened a newspaper, or turned on the television, you saw the orange, glowing donut. We discussed here on the Everyday Einstein podcast, two years ago when the observations were first taken, what kind of telescope—or rather a globe-spanning combination of telescopes—was needed to take such an image. 

See also: What Happens If You Fall Into a Black Hole?

So what do we make of the image now that it’s finally here? What exactly are we looking at? Is it what we expected? And what’s next?

Here are 5 facts about the first ever image taken of a black hole:

Why is this the first image we’ve ever taken of a black hole?

Supermassive black holes like to lurk in centers of massive galaxies like our Milky Way, but despite being so common, before last Wednesday, we had never actually seen one. Astronomers had only been able to infer their presence based on the motions of stars that orbit them or the energetic radiation that gets emitted as the matter being gobbled up by the black hole heats up. The problem, of course, is that black holes are so dense that their gravity becomes so strong that not even light—massless, fast-traveling light—can escape. Black holes are, by definition, black. 

Humanity got our first look at a black hole last week, however, thanks to the use of radio waves and an observational trick called interferometry. In an interferometer, multiple telescopes are used together to mimic one larger telescope and thus observe with finer detail than would be possible on their own. Such observations are only now possible thanks to world class radio telescopes, the invention of the algorithms required to analyze their data, and, of course, a team daring enough to try it.

The black spot at the center of the image encompasses the black hole itself, including its event horizon, the point of no return for any matter and light, as well as the shadow it casts on its surroundings.

Why is the black hole shaped like a lopsided donut?

The black spot at the center of the image encompasses the black hole itself, including its event horizon, the point of no return for any matter and light, as well as the shadow it casts on its surroundings. This “shadow”...

Keep reading on Quick and Dirty Tips