In April of this year, astronomers revealed one of humanity’s greatest achievements in science – the first-ever image of a black hole. (Of course, the photo wasn’t directly of the black hole itself, that would be impossible. More on that later.)
Stunning as that was, to the casual observer who may not have known what to expect, it was a bit… blurry. It took an incredible amount of time, data, and skill by an extremely dedicated team to take that blurry photo and one day we will have real “razor-sharp” color video footage of one, they’ve since promised. But until then, NASA has released a stunning simulation of what that black hole would look like in all its crystal clear glory.
Before that first image, the only way to look at a black hole was indirectly, observing its effects rather than the object itself. By their very natures, black holes swallow light, making them rather difficult to look in the eye.
Black holes are objects that generate a field of gravity so strong that nothing in its vicinity – including light – can escape.
Right on the edge of that precipice is the event horizon, the threshold where to escape the pull of the black hole you’d need to move faster than the speed of light – and according to Einstein’s theory of special relativity, nothing in space can move faster than the speed of light. It’s the shadow of the event horizon of the black hole at the center of galaxy Messier 87 that astronomers managed to photograph.
The orange donut in the image is the black hole’s accretion disk – a flat spinning disk of gas, dust, and stellar debris that orbits the black hole, not quite falling in. We can see this disk because the immense force of the black hole’s gravity accelerates the spinning particles and they smash into each other, releasing X-rays and gamma rays in visible light, which allow us to observe – and now take photos.
The incredible visualization, released by NASA’s Goddard Space Flight Center for its Black Hole Week, shows how that extreme gravity warps our view of the light by altering its path as it's emitted from different regions of the disk, giving it a misshapen look.
The part of the disk closest to the black hole spins at close to the speed of light, while the outer part spins more slowly. As magnetic fields wind through this churning disk, bright blobs form and disappear. The different speeds of the inner and outer disk stretch these blobs, creating what look like lanes in the disk.
Importantly, this new simulation shows the disk from the side instead of face-on. At this angle, the light that is technically coming from behind the black hole is warped to look like an arc or hump over the black center. Also, if you look closely, the left side shines brighter than the right side. The simulation shows the gas that flows towards us is brighter because of a phenomenon called relativistic, or Doppler, beaming – much like a lighthouse light is brightest as it points directly at us in its arc, getting dimmer as it moves away from us.
Simulations like this help us understand what we can't see but know is occurring around black holes, and they help us to get to grips with what we're actually looking at in the one incredible image we do have.