Cameron Gibelyou, BHP Science Advisor
A note from BHP: To capture the excitement of the black hole image and your questions about it, Cameron will be holding a special Yammer Exchange, Monday, April 15th. Join in on the fun, and get all your “supermassive” questions answered about black holes!
What’s the news?
If you’ve looked at the Google home page or any science news in the past day, you’ve seen the announcement: Astronomers have captured the first-ever direct image of a black hole. It is a huge black hole with a mass about 6.5 billion times greater than that of the Sun, over 50 million light-years away, in the middle of a galaxy called M87. The image of this “supermassive” black hole comes not from a single telescope but from combining data from multiple telescopes around the world.
Why is this important?
Black holes pack an immense amount of mass into a very tiny region of space. They are dense, compact, and have such strong gravity that not even light can escape from them. Astronomers already knew the locations of many black holes in the Universe (including this supermassive one in M87 – which is why they knew to look there!) and had studied them by observing how matter behaves in the extreme conditions near black holes. Theoretical physicists knew that due to the capture and bending of light near a black hole, there would be a “shadow” around it, a dark region somewhat wider than the black hole itself.
The new image is the first to directly show a black hole’s shadow, and comes as close as possible to giving a picture of the black hole itself. The telescopes used to create this image have such strong resolution that they could distinguish an orange on the Moon’s surface. Such powerful resolution allows for astronomers to observe the details of the black hole’s shadow, including its precise size and shape, and see whether data supports theory – in this case, Einstein’s theory of gravity, the general theory of relativity. The scientists who make observations like this hope that the detailed resolution of this image, and others like it that will come in the future, will allow for more detailed investigation of the supermassive black holes that lie at the center of large galaxies like M87 and our own Milky Way Galaxy, and further testing of Einstein’s theories in the extreme conditions right near the edge of a black hole.
Also, it’s a direct image of a black hole. That’s just cool.
Great article and especially video here:
 The telescopes are radio telescopes, the ones with the big “dishes.” The technique of combining observations from multiple radio telescopes is called Very Long Baseline Interferometry (VLBI).
 Scientists even succeeded in detecting gravitational waves from the collision of two black holes through the LIGO project in 2016.
 The “edge” of which is called the “event horizon,” past which no light can escape – this is about 2.5 times smaller than the shadow.
 You may have seen artists’ representations of black holes before, but they are not direct images.
About the author: Cameron Gibelyou, PhD, is a teacher and educator based at the University of Michigan. He holds a doctorate in astrophysics and has taught Big History at high school and college levels, as well as college classes in physics, astronomy, psychology, English, and applied liberal arts. Since 2011, he has worked with the Big History Project as a developer of teaching materials, expert reviewer, and science advisor.
Cover image: National Science Foundation and Event Horizon Telescope contribute to paradigm-shifting observations of the gargantuan black hole at the heart of distant galaxy Messier 87. By Event Horizon Telescope – EHT Collaboration. First Image of a Black Hole. ESO., CC BY 4.0.