For the first time, Astronomers have taken extreme close-up observations of the black hole in the center of our galaxy.
The black hole, called Sgr A*, has over 4 million times the mass of the Sun and is 25 million kilometers wide. If it were on the Moon, it would be about the size of a US quarter.
The black hole cannot be seen. Material falling into a black hole falls into a disk called an accretion disk, which is outside the black hole itself. The material gets very hot and emits light that can be detected.
The amazing image is here.
The material is less than 60 million kilometers from the black hole. The shadow of the black hole is not the black hole itself, but the dark hole in the center.
It was possible to link up eight telescopes across the planet, giving them the same keen eyesight as a single telescope. Astronomers were able to combine their observations and peer into the dark heart of our galaxy because they observed in the same wavelength of light as a microwave.
The point in space near a black hole where, no matter what you do, you're falling in, is referred to as the event horizon telescope. The size of the black hole is sometimes called this. There is nothing to see in the event horizon. Light cannot escape from the event horizon.
If the image looks familiar it is because it has a striking resemblance to the first EHT image of the black hole. The black hole is about 1,500 times larger than ours, and 2,000 times farther away. It looks larger than ours in the sky.
They are very different. The M87 black hole is so large that it takes days and weeks to travel around it once. The images have to be taken much more quickly to avoid the details being thrown out. Many images were combined to create the Sgr A* image, which shows an average of the images.
The material around the black hole has a powerful magnetic field embedded in it, and along with the intense gravity this sculpts much of the behavior of the extremely hot gas. The bright spots may be where the magnetic field is a bit stronger, squeezing the material a little harder and making it glow stronger, however given all the uncertainties in the image process it's unclear if these glowing spots really do represent much brighter spots or not.
It's important that images like this are present. It was decades later than technology could see stars around the black holes in the centers of the big galaxies, but in the 1980s it became clear that all of them had black holes. The stars were tens of billions of kilometers from the black hole, and seeing something on the scale of a few tens of millions of kilometers was impossible until the past few years.
The images show the environment around the black hole, where Einstein's theory of gravity and relativity reign supreme. That is a very big deal. Black holes are just plain weird, but we have a pretty good idea of how they behave.
It's amazing to be able to get these images. It is difficult to peer through all the material in the center of the universe to see the black hole and the hot gas in the accretion disk. It's difficult to overstate the magnitude of this breakthrough.
These images show us that black holes are real. An object with millions of times the mass of the Sun yet completely, utterly dark, a hole in a ring of tenuous material millions of degrees hot but flowing around something we cannot see; only its effects on objects around it can be detected.
The Universe is a wonderful place, and what these images show is that we can understand it. When we join together across nations and let our curiosity guide us, we can look into the strangest places the universe has to offer.
All Rights Reserved © 2024
