The Race To See The Black Hole At The Center Of Our Galaxy
We've never observed a black hole directly, but with a wild collection of telescopes, these astronomers are determined to be the first.
Sagittarius A* might just be one of the most fascinating regions of our galaxy. Scientists believe this is the location of a supermassive black hole, approximately 4 million times the mass of our sun. There is plenty of evidence that this black hole exists, yet naturally there are still some skeptics out there.
The main reason for the skepticism is that no astronomer has actually directly observed this black hole -- nor any black hole for that matter -- but that could change very soon.
In this DNews documentary, we take a trip to the Cerro Paranal in the Atacama Desert in Northern Chile, one of the driest places in the entire world. That makes it an ideal location to build the most powerful telescopes on the planet.
However, astronomers cannot easily observe a supermassive black hole with just one extremely large, powerful telescope. They need multiple large, powerful telescopes -- four to be exact. The Atacama Desert is where The 'Very Large Telescope' (VLT) lives and is managed by the European Southern Observatory (ESO). It is there that the happenings of Sagittarius A* can be observed through these four optical telescopes.
Scientists employ a technique called interferometry in order to harness the power of these telescopes. Usually an optical telescope's resolution is limited to the size of its internal mirror, but using interferometry with the VLT array makes the possibilities much greater. A powerful computer combines the light beams that come from each telescope, creating a virtual mirror that can be as wide as the distance between them.
There's also another telescope very near to the VLT known as the ALMA: Atacama Large Millimeter Array. That radio telescope has 66 antennas that can be used to study certain regions of space that the VLT cannot reach.
What's even more exciting is that in 2015, ALMA became part of a united network of radio telescopes around the world called the Event Horizon Telescope (EHT) that are also connected using interferometry. So basically, the Event Horizon Telescope is a virtual radio telescope that is the size of the entire planet. It is the largest astronomical project to ever exist.
The goal is to use the EHT to observe 'the event horizon' of Sagittarius A's supermassive black hole by next year. The event horizon is the boundary that depicts the limit of the black hole. Beyond that limit, nothing can escape.
This has never been done before and could serve to further prove that the black hole exists. However, the astronomers working on the project say that their main goal isn't to prove the black hole's existence, it's to gain scientific knowledge about the nature of space and time. They want to further our collective knowledge about the universe we live in.
-- Molly Fosco
The New York Times: Black Hole Hunters