Black holes. Parts of our unknown universe where the only pictures we have are the images we concoct in our minds.
How are black holes formed? Near the end of their life cycles, stars collapse on themselves because of low fuel. This strong, quick collapse causes the star to explode—a supernova. The future of the star’s leftover core is then determined on the star’s original mass. The high mass star has two possible outcomes: a neutron star or a black hole.
How can black holes grow to be very large if they begin very small? To grow in both size and mass, black holes must devour all the objects in their paths which are most often other stars. Once the black hole has absorbed the object, it cannot escape because of its strong gravitational pull. This pull is so strong that it even prevents light from crossing through it. So black holes are definitely a force to be reckoned with. Also, because of this characteristic of black holes, it is difficult to capture an image of them since it would show up fully black.
After over ten years of hard work, on April 10, 2019, a picture of the far-away black hole Messier 87 (M87) has been released. Now you may ask, how was this photo taken? You just said that we can not take a picture of black holes directly because the image would appear completely black. How was a photograph of M87 obtained?
A group of people thought to use glowing gases around the black hole to outline it. This allows us to see the silhouette of the black hole. Brilliant, isn’t it? To take this image of a black hole, they had to use a virtual telescope. The Event Horizon Telescope (EHT) consists of a web of telescopes across the globe and an enhanced version of an old technique used to view objects in space: the Very Long Baseline Interferometry (VLBI). This technique uses telescopes all over the world to target a certain object in space simultaneously and gather information on the specified target.
Is the VLBI method effective on black holes? Yes. Why? Because a while ago, astronomers and scientists decided to test it by selecting a couple of black holes, pointing the telescopes towards them, and then trying to produce an image from the information gathered. The result was impressive.
Out of the many black holes throughout our universe, two black holes had been selected for the testing: Sagittarius A and M87. Sagittarius A, a black hole 26 000 light-years away from Earth, was chosen because of its proximity to our planet as well as the size of the black hole. The second black hole, M87, a black hole 53 million light-years away, had been chosen because it had been active at the time, unlike Sagittarius A.
Afterwards, using telescopes as far as the South-Pole and Spain, scientists and astronomers gathered information on the black holes. This information was then sent to a central location where the time stamps of the eight telescopes were coordinated to produce images of the silhouette of the black hole’s event horizon. The result is the remarkable image shown above.
Additionally, thanks to this black hole image, important questions about black holes are now getting answered. For example, this picture helps scientists and astronomers validate observation methods and theories. Also, by taking this picture, we were given a more accurate method of reading a black hole’s mass. This new information will help astronomers along with scientists, create more images of black holes and help humans learn more about these mysterious black holes.
As astronomers and scientists continue to gather data from the telescopes on the second black hole, Sagittarius A, humankind finally begins its journey on solving the once-thought unsolvable case: black holes.
Lutz, Ota. “How Scientists Captured the First Image of a Black Hole.” NASA: Jet Propulsion Laboratory, 19 Apr. 2019. Web. Accessed 24 Apr. 2019.