Black holes are notoriously difficult to catch on camera. They are completely dark objects that consume unsuspecting objects that get too close..
Just before stars and gas fall into black holes they spiral around and around as if caught in a whirlpool. They emit a great deal of light as a sort of “last hurrah” as they are torn apart en route within the black hole surface, or event horizon. This light is evidence that a star was recently there. It also means that when black holes are consuming stars they are not entirely black. The dark center is surrounded by a ring of light.
That is how the story goes, anyway. We are quite (but not completely) sure that black holes exist. There is a great deal of circumstantial evidence to support this mathematical solution first proposed by Karl Schwarzschild in the early 20th century. One detail missing is that we have never actually seen one. We need verification. If yes, then we will be able to study space and time under the most challenging physical conditions imaginable. If no, then we will need to make modifications to our understanding of gravity.
The first studio subject is the supermassive black hole at the center of the Milky Way. This object is small, packing a mass of about 4 million times the mass of the Sun into a body that is one-tenth the average distance from the Earth to Mars. It is also interesting, as it is the cloest one to home.
To have the great hope to see the ring of light surrounding the black hole that would be one of its tell-tale signatures requires extremely high quality imaging. The technology demands cameras attuned to such fine detail that they will be able to see grapefruit on the Moon as seen from Earth.
Next week we will explore the technology behind this powerful new camera requiring collaboration of astronomers from eight different telescopes worldwide.