NASA defines a black hole as “a place in space where gravity pulls so much that even light cannot get out. The gravity is so strong because matter has been squeezed into a tiny space. This can happen when a star is dying.” Because no light can get out, people can't see black holes. They are invisible. Space telescopes with special tools can help find black holes. The special tools can see how stars that are very close to black holes act differently than other stars.
What does today's black hole image news mean? Our
— NASA (@NASA) April 10, 2019
@ChandraXRay Observatory team puts it into
perspective and shares just what a difficult feat it was
for @NSF and @EHTelescope to obtain the new black
hole image. Read more about #EHTBlackHole:
https://go.nasa.gov/2G53mgk
NASA was successful in obtaining a picture of a black hole located over 50 million light-years from us, in a giant galaxy called “Messier 87”. Telescopes of all types are used to see distant objects. The larger the diameter, or aperture, of the telescope, the greater its ability to gather more light and the higher its resolution. A team was formed to capture the image of the black hole and they started by building a network of telescopes, known as the “Event Horizon Telescope(EHT)”. A technique called “Very Long Baseline Interferometry(VLBI)” was used which allows the imaging of distant objects.
The M87 black hole was not the first choice. The first choice was “Sagittarius A”, which is located in our Milky Way Galaxy. Though it is very large in size, it was not chosen because being in the same galaxy, the team would have to look through a lot of “pollution” caused by stars and dust to image it. Therefore, there would have been more amount of data to filter during the processing of the image. On the other hand, the M87 black hole is one of the largest known supermassive black hole. Unlike “Sagittarius A”, M87 is an active black hole, which means that matter falls into it and spews out of it in form of jets of particles, nearly at the speed of light. Katie Bouman(computer scientist), who led development of algorithms of the telescope data described the capturing of the image of black hole as equivalent to “capturing an image of an orange on the surface of the moon”.
By 2017, EHT consisted of eight sights around the world. All the telescopes at these sights had to be highly synchronized with each other and accuracy of even a fraction of a second was required. This precision was achieved by using an atomic clock. Each telescope acquired data from the satellite and then, the digitized data and time stamp were recorded on a computer disk. The size of the final data was around 5 petabytes.
This was a great achievement in research of black holes. The team is now working on generating image of Sagittarius A.
Quote of the blog:
“Do you realize that if you fall into a black hole, you will see the entire future of the Universe unfold in front of you in a matter of moments and you will emerge into another space-time created by the singularity of the black hole you just fell into?”