Astronomers are set to give the world something entirely new Wednesday: the first-ever images of actual black holes.
Or, rather, of everything around Sagittarius A* and another black hole at the center of the Messier 87 galaxy, since even light can’t escape a hole’s “event horizon” because the gravitational pull is too strong.
The images are the result of radio-signal data from eight separate radio telescopes across the globe, compiled into a single picture by the use of atomic clocks to synchronize the partial images in a technique known as Very-Long-Baseline Interferometry. In effect, it’s a single telescope (the Event Horizon Telescope) the size of the Earth.
What you’ll likely see is, well, nothing: the lack of light emissions that defines the hole itself — surrounded by a turbulent disk of plasma and gas that’s gradually being pulled into the hole, as well as jets of supercharged particles blowing away from the disk.
With a mass 4 million times that of the sun, Sagittarius A* is at the center of our Milky Way galaxy. The hole in galaxy M87 is much farther away but even larger, at 7 billion solar masses.
First deduced from Albert Einstein’s field equations of general relativity, the existence of black holes has gradually become established science, confirmed by secondary effects.
But Wednesday’s images will represent confirmation of a different kind — and yet another step forward for science.