Black holes have come a long way since the days of Einstein. Where once they were just theoretical nightmare objects, now we know they’re verifiably real. Or, at the very least, we know objects that look, sound, and feel like black holes exist in the universe.
We’ve learned quite a bit about the mysterious objects in the years since we first imagined them with complex math and equations.
From supermassive black holes shooting material across tens of thousands of lightyears to millions of Earth-like exoplanets orbiting black holes no more massive than our own star, here are 10 new awesome facts about black holes.
10. The Fermi Bubbles Are Left Over from a Massive Explosion
Above and below our galaxy, stretching 25,000 lightyears each, are two bubbles of gamma-ray energy. These Fermi Bubbles were first discovered in 2010 by a group of scientists at the Harvard-Smithsonian Center for Astrophysics.
These bubbles are the remnants of a powerful explosion that came from the supermassive black hole at the center of our very own galaxy. An explosion that lifeforms on Earth, maybe even our apelike ancestors, may have witnessed 3.5 million years ago.
To put how massive these Fermi Bubbles are into perspective, Alpha Centauri is one of our closest neighboring stars. It’s 4.3 lightyears away, and even so, with our current technology, it would take at least 100 years to reach it.
To travel the distance that these Fermi Bubbles take up, it would take 137,000 years to cover that distance at current speeds.
But what’s interesting is that the eruption of nuclear energy that came from our supermassive black hole would have been much larger than the remnant it left behind, covering a distance of over 100,000 lightyears.
9. Their Jets Can Stretch Millions of Light Years
Speaking of eruptions coming from black holes, let’s talk about the Small and Large Magellanic Clouds, two dwarf galaxies that orbit our peaceful Milky Way. A stream of gas is left trailing behind the dwarf galaxies, reaching an incredible distance of 600,000 lightyears away from them. Scientists believe these are remnants of two gargantuan explosions of energy that would have erupted around the same time that the Fermi Bubbles were formed (give or take a million years or so).
But Relativistic Jets are far more common than you might think. They’re thought to be the result of energetic particles being flung out of the orbit of the black holes they orbit at near the speed of light. We’ve observed many of these incredible light shows at the poles of other galaxies, and some of them, like the Centaurus A radio galaxy, can reach as far as tens of millions of lightyears.
Their destructive force is nothing to sneeze at, either. Some of these explosions are powerful enough to consume their entire galaxy. Something that would wipe out any hypothetical life or habitable worlds in the process.
We’re pretty lucky our galaxy is so calm.
8. NASA’s TESS Imaged the First Black Hole Eating a Star
NASA’s TESS (or Transition Exoplanet Survey Satellite) managed to catch an incredible event after watching the stars in the galaxy 2MASX J07001137-6602251 (and yes, that is its name). Amazingly, it detected a brightening from one of the galaxy’s stars and confirmed that a tidal distortion event had occurred.
After enlisting NASA’s Neil Gehrels Swift Observatory and others, astronomers were able to determine that the event they were observing was the world’s first look at the early moments of a black hole consuming a star.
When stars get too close to a black hole, they end up being torn to pieces, creating a long tail of gas as the star’s material gets stretched into an accretion disc around the black hole. These events only happen about once every 10,000 years in galaxies the size of the Milky Way, but thanks to satellites and observatories like TESS and Neil Gehrels, we’re able to see them as they happen (or happened) in other galaxies.
Eerily enough, the star is about the size of our own.
7. Earth is Actually 2,000 Lightyears Closer to Sagittarius-A Than We Thought
Throughout most of our lives, scientists and astronomers thought that our solar system rested on the outer edge of the galaxy (the stellar boondocks, if you will), but it seems as though that isn’t true after all.
It’s difficult to measure a thing as big as a galaxy from the inside, let alone figure out where exactly our planet is within it. But the National Astronomical Observatory in Japan has new data which suggests that we are about 2,000 lightyears closer to Sagittarius-A (our supermassive black hole) than we originally suspected.
Being closer also means that we’re moving much faster than we thought as well, traveling at an incredible speed of seven kilometers per second.
6. One Million Habitable Worlds Could Theoretically Orbit a Black Hole
Our typical desire is to find exoplanets around stars like our own, and while we’ve found a few of those, and a few thousand around stars totally not like our own, we tend to be pretty biased about where we think life can and cannot arise. After all, it happened on Earth, so clearly that’s the most likely scenario. Right?
Well, it turns out that black holes heat objects orbiting around them pretty efficiently. This is due not only to tidal forces that orbiting planets might experience (similar to what red dwarfs do to their orbiting exoplanets) but also through the cosmic microwave background radiation that gets sucked into the black hole. This energy is normally extremely cold (as it’s leftover from the big bang) coming in at about three degrees above absolute zero. But after falling into a black hole, it gets really, really, really freaking hot.
And if the black hole is spinning, then the light it produces from eating all that microwave background radiation can be as bright as a star.
That’s not all, either.
Because of the immense gravity that black holes exhibit, they could host up to one million habitable worlds—depending on the mass, of course.
5. They May be… Fuzz Balls?
So, String Theory is weird. Really weird. And one hypothesis that String Theorists will often bring up is the idea that black holes are not black holes at all, but rather balls of yarn.
This is most likely a metaphor, but another comparison would be to imagine if all matter in the universe is made up of quantum strings as String Theory suggests, and we envision those strings as, say, rats? then black holes would be like a rat-king (a collection of rats that have their tails fused together) with all of those precious strings fused into one ball of fuzz.
While we do have the first image of a black hole on file now, we still don’t know a lot about them. So, it stands to reason that we might not understand their mechanics either.
4. There’s One 1,000 Lightyears Away
Black holes are extremely hard to identify if they aren’t in the middle of eating a star, or at the center of a galaxy. But astronomers say they’ve found a star system 1,000 lightyears from Earth that feature telltale signs of a black hole affecting the system.
This is a triple star system, with two B-type main sequence stars that are clearly visible without needing a telescope on Earth. Previously this system was thought to be binary, but after observing that the orbits of the two stars were being affected by something else, causing them to be skewed, a follow-up study was commissioned using a 2.2-meter telescope at the Las Silla Observatory in Chile. The results of this study show that one of the stars orbits a gravitational center every 40 days, a mass that is not its binary partner.
This means there are three objects in this system, not two. And since one of those objects is invisible to us, the third object is very likely to be a black hole.
How cool is that?
3. Information Can Escape Black Holes
Black holes have long had the reputation of being absolute (theoretical) monsters that could swallow light, matter, and information. That information, at least before the papers we’re going to talk about, was thought to be lost forever–sealed inside the black hole which ate it.
This is a problem for physicists because the laws of thermodynamics demand that information cannot be destroyed. But further complicating this is Stephen Hawking’s theory that black holes about the mass of our moon evaporate.
This is a problem. Because if the black hole evaporates, what happens to the information that said black hole has consumed?
Well, we’ve never seen a black hole evaporate. So, we don’t know what happens during such an event.
But two groundbreaking papers seem to suggest that when black holes get on in age, they begin to break down. Meaning that information can both escape from a senior black hole and any new matter being introduced to it would be regurgitated almost immediately.
2. Swarms of Primordial Black Holes Might Fill the Universe
Mini black holes left over from the beginning of time and space as we know it (the big bang) may be swarming around our universe. It might sound like science fiction or fantasy, but researchers think they might be able to actually detect the aftershock leftover from their birth.
The laws of physics allow for the existence of black holes at any size, and these primordial black holes are thought to have masses equivalent to planets.
Right after the big bang, at the moment of inflation, researchers suggest that there might have been a moment when space-time was curved before eventually flattening out. That momentary curvature is thought to have produced fluctuations in the expanding universe. Ones intense enough to form Earth-mass black holes.
The researchers propose that observatories with the capability to detect gravitational waves start searching for what they call secondary gravitational waves.
These theoretical perturbations in the universe would radiate much weaker gravitational waves than an ordinary black hole or even a neutron star collision. The perturbations would be the remnants of the event which would have spawned these primordial black holes.
1. The First Image of a Black Hole Ever
But the process behind how the image was obtained is pretty cool too. The observatories taking part in the project to image the black hole in the M87 galaxy are part of the Event Horizon Telescope project, consisting of 200 scientists from 20 countries.
This effort required ten years of work, eight of the world’s most sensitive radio telescopes, a network of synchronized atomic clocks, and two custom-built supercomputers that would make Bill Gates weep.
Now, the black hole was originally imaged in 2017, but it took roughly three years to analyze the data and interpret it into an image.
The Event Horizon Telescope project isn’t done yet, either. They’re adding more radio telescopes to their network and gearing up to point their dishes at the supermassive black hole in the center of our galaxy.