Most Images Of Black Holes Are Illustrations. Here’s What Our Telescopes Actually Capture

Impossibly dense, deep, and powerful, black holes reveal the limits of physics. Nothing can escape one, not even light. Even though black holes excite the imagination like few other concepts in science, the truth is that no astronomer has actually seen one. We’ve “heard” them, so to speak, as scientists have recorded the gravitational waves (literal ripples in spacetime) emanating from black holes that collided with one another billions of years ago.

But any photo you’ve seen of a dark mass warping spacetime … well, that’s just an illustration. Like this one:

This soon may change. An audacious global project called the Event Horizon Telescope is currently working to piece together an image of a black hole for the first time. And if it does, it will be a remarkable accomplishment. Because as massive black holes are, they’re actually incredibly hard to see up close.

Black holes are born when massive stars collapse in on themselves and create a region of gravity so intense that not even light can escape its grasp. Astronomers also speculate that some black holes may have been formed in the early chaotic universe after the Big Bang. The biggest problem with trying to see a black hole is that even the supermassive ones (with masses millions of times heavier than our sun) are relatively tiny.

“The largest one in the sky [is] the black hole in the center of the Milky Way,” Dimitrios Psaltis, an astrophysicist at the University of Arizona, explained in an email. “And taking a picture of it would be equivalent to taking a picture of a DVD on the surface of the moon.”

What’s more, because of their strong gravity, black holes tend to be surrounded by other bright matter that makes it hard to see the object itself. That’s why when hunting for black holes, astronomers don’t usually try for direct observation. Instead, they look for evidence of the effects of a black hole’s gravity and radiation.

“We typically measure the orbits of stars and gas that seem to circle around very dark ‘spots’ in the sky and measure how much mass is there in that dark spot,” Psaltis says. “If we know of no other astrophysical object that can be so massive and so dark as what we just measured, we consider this as very strong evidence that a black hole lies there.”

Some of the best indirect images of black holes come from the Chandra X-ray Observatory. “The friction and the high velocities of material forming out of a black hole naturally produces X-rays,” Peter Edmonds, a NASA astrophysicist and communications specialist working with Chandra, said. And Chandra is a space telescope specially designed to see those X-rays.

For example, the Chandra observatory documented these X-ray “burps” emanating from the merger of two galaxies around 26 million light-years away. The astrophysicists suspect that these burps came from a massive black hole:

Similarly, the fuchsia blobs on this image are regions of intense X-ray radiation, thought to be black holes that formed when two galaxies (the blue and pink rings) collided:

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