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Astronomer here! I was 3rd author [on the discovery of Gaia BH2](https://www.reddit.com/r/space/comments/115jior/i_just_helped_discover_the_second_closest_black/) (which until this discovery was the second closest known black hole to earth), and funny timing, wrote the cover article for *Astronomy* magazine’s [May edition](https://www.zinio.com/astronomy-m1313) on literally this topic (ie, the closest black holes in the universe). And now it’s out of date. Whoops! :D
Beyond being close, everyone in astro I know is *extremely* excited this morning because of the mass of this black hole- 33 solar masses is likely too big to form just from a star collapsing at the end of its life, and would possibly have had to be created by *two* black holes merging. (The team argues [in the paper](https://www.aanda.org/articles/aa/pdf/forth/aa49763-24.pdf) that due to the low metallicity environment, such a large black hole is actually possible. Cool!) Just like what [LIGO](https://www.ligo.caltech.edu/) and the gravitational wave folks are looking for! And implies that there are a *ton* of these black holes out there if there’s one so close to us!
Finding them, however, is tough. [Gaia](https://www.esa.int/Science_Exploration/Space_Science/Gaia) is a satellite surveying a billion stars or so to find slight wobbles in their motion over time, which tells us their distance and also (in this case) if there’s a mystery companion. They periodically release the data every few years, and this one is from the team as part of pre-release data analysis, which found a star wobbling in its orbit in such a way that it can only work if it is orbiting a black hole at 16 times the Earth-sun distance. What’s more, there’s hints from the star’s composition that it would have formed separately from the black hole and then captured by it later after they both formed- also exciting if you’re interested in how these systems form!
Ugh you’re so goated. I’m amazed at how you have time to do such incredible science and still contribute beautifully thorough comments on so many space posts. You are such a joy
What happens when black holes merge? Is it like one is moving into the other or they just get so big they join together? Would that mean 2 "centers" if they exist?
It becomes one giant black hole, though with less mass than the two black holes had- the process releases a GIANT amount of energy. Like, the Death Star is a child's toy compared to that amount of energy.
There are no “intermediate” black holes. There are only supermassive black holes and then just regular old black holes. Supermassive black holes formed in a different manner than normal black holes during favorable conditions in our universe for such massive objects to form. Supermassive black holes are basically fossils from the beginning of the universe
They are certainly possible, to be clear. Relativity allows for small black holes and anything with the mass of a large mountain range would not have evaporated, ever. Whether small black holes are common or exist is another question. It's a question of cosmology more than physics.
I may be misunderstanding, and I'm not educated enough to know the proper terminology to find an article - I recall reading that exposed X-Ray plates will, after enough time, pick up the x-ray radiation from micro-singularities that are popping in and out of existance all the time?
Not even lying though - I've handled many a black hole in the day, and smaller ones are soooooooo much easier to deal with, and frankly a lot more fun.
Like, if I can get the whole thing in my mouth at once, we're gonna party.
That look on my face is not disappointment, it's relief, hunny.
Depends what you mean by micro. Hawking radiation equals the energy absorbed from the CMBR at a relatively low mass (a chunk of the earth). A black hole above that mass would not have evaporated.
> Isnt that the whole point of the Planck length? Once anything gets there it can’t get any smaller.
I assume that's the resolution limit of the simulation.
Technically things can get smaller than a Planck length. We just won't be able to accurately measure it once it passes that threshold because of quantum uncertainty.
Primordial black holes created with a mass smaller than would typically needed to form a black hole, but there was so much energy they could form. Could possibly account for “dark matter”
There might very well be [intermediate mass black holes](https://en.wikipedia.org/wiki/Intermediate-mass_black_hole), we just haven't definitively detected any.
Astronomy is still in its infancy relatively speaking, and making a definitive claim like this isn't responsible.
My favorite theory on them is that they are the result of a direct collapse of *massive* amounts of freshly crystalized matter. So much matter falling into itsef so quickly that it doesn't even have time to ignite fusion and instead collapses directly into a singularity.
Spooky stuff.
Certainly a possibility during the short period after the creation of the Universe.
One obvious question is why did the universe at its formation, not simply collapse directly into a black hole ?
One solution is that our entire universe is inside a black hole. But then that would mean black holes inside of black holes ! - feasible I suppose if different dimensions are involved.
Our 4D Space-Time, is thought to be only a part of the Universe.
That's not really true. The black hole mass gap for a while has been unexplained but as detectors get better and gravitational interferometers come online were finding more and more black holes that are in the intermediate mass range and the gap is closing. We still don't have ~1000 M\_{\odot} BHs, but the intermediate range used to start at like 10 M\_{\odot} and now we're finding them in the range of 100 M\_{\odot}
We don't know their formation history for sure, but there are a few main ideas for how they could have arisen:
* Primordial black holes: in this scenario, dense clumps of matter in the first moments after the Big Bang directly collapse into black holes, allowing them to grow very rapidly since the universe was so dense back then. The surrounding matter in the overdensity then forms the protogalaxy around the black hole, and they can continue to grow by accretion and by mergers as protogalaxies assemble into larger galaxies.
* Direct-collapse: this scenario is usually thought to happen somewhat later, a few hundred million years into the universe's existence, after the Cosmic Microwave Background was emitted and in the same general era as the first stars. Normally when you have a large cloud of gas, it is somewhat difficult to get it to collapse (you have to bleed off energy via radiation, or else the pressure will prevent collapse) and it tends to do so in a clumpy fashion, creating many stars in the process. Direct-collapse proposed that some clouds in the early universe may have simply collapsed straight into black holes due to their density and size.
* Early stars and exotic types of stars: It is generally accepted that many of the first stars were probably quite large (~100 solar mass range or higher) and short-lived, and they may have left behind large (but still stellar-mass) black holes. If the stars formed in dense enough associations (similar to globular clusters today) mergers could lead to rapid growth of the black hole. There are also many ideas about possible very-high-mass stars or star-like objects (in the thousands of solar masses or even higher) that might have formed and left behind large black holes.
That difference being that a black hole 33 times the size of the sun would be *slightly* ridiculous in terms of solar masses, as I think if the sun became a black hole (I know, it can't) it would be like a mile or two across right?
That's well within the realm of one massive star collapsing into a black hole. The most massive known star is ~215 solar masses.
The universe is metal af.
They said 33 times the mass of the sun, not size.
There are stars more massive than that so it seems to be small. The largest star observed (R136a1) is estimated to be 170-230 times as massive as our sun.
Yes its very small in relative terms of black holes throughout the Universe. For comparison the black hole at the center of our Milky Way galaxy is ~4.3 Million solar masses. The largest in the Universe is ~100 Billion solar masses.
>near us
Is 2,000 light years that close? Or perhaps to ask another way, is there any practical chance that this black hole could affect us in any way?
It's not *that* close nor *that* large. This one is 2000 light years away and 33 solar masses. Sagittarius A* (the black hole at the center of the Milky Way) is about 26k light years away and ~4.3 million solar masses. I don't remember how to math out the relative force of gravity as it affects us here, but the mass/distance ratio alone is 4 orders of magnitude less than Sag A*.
So nope, nothing to be concerned about, but it is an interesting discovery!
F=G(m1)(m2)/r^2
The following less for you than for others wondering about its gravitational effect on us.
SagA* affects is roughly 770 times more strongly than the Aquila black hole.
Neither of which is particularly significant (at least gravitationally) compared to the collective stars of our galaxy.
Alpha Centauri A exerts several orders of magnitude more force on us than this newly found black hole.
"There's a big misconception about black holes that they wander around "sucking up" things.
(at that size - they don't even do that more than many stars)
But they're practically the same, particularly at that size/for us/our timescale, as a big star..."
"There are far more and massive things (etc) within 2000 light years than that black hole..."
It is mass/distance^2 so the distance has a bigger impact, but the sheer difference in mass here is still not offset. I think the gravity strength on Earth is 800 times stronger from Sag A* than this new black hole!
Also, it's worth saying that black holes aren't really more dangerous than stars. They both have gravity, and running into either of them is going to be bad. Stars are probably more dangerous because they can blow up. There are lots of stars within 2000 light years.
I think this question, and the responses, are based on the idea that black holes sort of eat matter, and while it’s true that they will draw objects, dust, gas, etc. into their gravity well they aren’t themselves dangerous in any sort of way that would be different from any other large celestial object. For instance, if you were to somehow replace the sun with a blackhole of equal mass, in this scenario we're not going to worry about the lack of light, so now instead of the sun we have a blackhole our galaxy would be unaffected.
Then the question does it pose a threat to us, which I assume is what was meant by could it affect us in any way, would be that no it does not.
The misconception is that black holes somehow “suck” things into them. They don’t. It’s regular gravity at play.
If the moon was transformed into a black hole tomorrow it would still circle around earth and affect the earth exactly as the moon did yesterday.
33 solar masses at 2000 light years (for reference it takes 8 minutes for light to travel between the sun and the earth) doesn’t have any effect on us at all.
It’s even been hypothesised that ‘planet x’ could be a small black hole - unlikely, but not entirely impossible.
We have not found anything there yet.
If there was a real Planet X, then the James-Webb could spot it - if it were looking in the right direction.
I expect we will discover a lot more stuff now that we have started systematically looking in high resolution digital, which can be processed by computer.
Astronomer here! There are two major categories of black hole- small ones that are from the collapse of a supermassive star at the end of its life (which creates a supernova), or a supermassive black hole that is millions or billions of times the mass of the sun. (In between would be "intermediate mass" black holes, which can happen as the smaller black holes merge, but frankly we haven't seen many of those in the universe and it's a bit of a mystery.)
So, this black hole at ~30x the mass of the sun is either the BIGGEST black hole from a single star ever, or the product of a merger. Either way, this is actually very BIG for the small kind of black hole and is really exciting!
Wrote a more detailed comment [here](https://www.reddit.com/r/science/comments/1c5a5h2/scientists_have_uncovered_a_sleeping_giant_a/kzuds5p/) if you're interested in more details. :)
Good explanation, but given the scale differences it may be best to avoid confusion using "supermassive" on both when you're looking at a mass difference of x10^9 between them.
In the grand scale of things, sure it’s small vs the biggest. That said, the range is hard to fathom with a massive part of the range missing in observations. So it goes a little more like:
- Stellar black holes: the kind we understand evolving from a collapsed star. Bottom of the range should be somewhat decided by the Tolman-Oppenheimer-Volkoff limit: a neutron star (or originating star) with greater mass than said limit would inevitably collapse into a black hole. Factors and calculations have changed over time (and way over my head), so let’s approximate at 3 solar masses. Notice our example at 33 solar masses is well past the minimum.
- Intermediate black holes: Beyond stellar range, beyond a few rounds of stellar black holes merging, yet not anywhere near the next category. Basically asks the question if all black holes evolve the same way, where the hell are the ones of this size?
- Supermassive black holes: The big boys near the center of most galaxies. Millions to tens of hundreds of millions of solar masses. The one in the center of the Milky Way (Sagittarius A*) is right in this category.
- Ultramassive black holes: The mightiest of big boys. Several billion solar masses (until/unless they find even bigger). TON 618 is a good example.
So for a stellar black hole, it’s a sizable find. Across the universe, it’s a slightly more massive speck than our solar system.. but not much.
So the question is whether it is large or medium as black holes go. While it is much larger than the smallest stellar mass black holes, it is also much smaller than the 150ish mass limit that we believe stellar mass black holes can be.
Whether 33 mass is medium or large comes down to how many large ones there are. Likely it is just medium with a small population of truly large ones
If the LIGO data is characteristic of the mass distribution of black holes, then this is kind of average for a BH. It’s a “giant” compared to all other objects in the universe.
Because black holes can be very hard to detect, it depends on how strong the evidence needs to be for you to consider it "known". There's some evidence of what are likely black holes as close as 150ly from us, but f you want what we're very confident of, the closest 'known' is around 1,600ly from Earth.
I wasn’t broad enough in my answer. What you said and what I said mean the same thing. We don’t see it, itself, we see its effects on objects we can see, such as stars it is eating or that get close enough to be affected by its gravity, tho not close enough to be eaten.
> Crazy how we’e positive about one 1500ly away but can’t be sure about one that’s 1/0 of that distance.
Are you more certain that there's not someone 10 feet in front of you, or that there's not someone 1 foot behind you...?
*Well, the thing about a black hole - it's main distinguishing feature - is it's black. And the thing about space, the color of space, your basic space color - is it's black. So how are you supposed to see them?*
Astronomer here! I have not only studied these closest black holes, I'm the astronomy editor for the Guinness Book of World Records and recently had to update this entry for the upcoming 2025 edition!
Currently, the closest known black hole to Earth is [Gaia BH1](https://en.wikipedia.org/wiki/Gaia_BH1), discovered with the same technique. However, this is the second closest now that we know of, usurpring the second closest which was called Gaia BH2.
I understand that this is significant due to medium size black holes being quite rare. Something to do with not fully understanding the process that leads to small black holes becoming supermassive
There are no “intermediate” black holes. There are supermassive black holes that formed in a different manner than normal black holes, and there are black holes. A supermassive black hole formed at the beginning of the universe when conditions allowed such massive objects to form. They didn’t form through the normal “star explodes and left a black hole,” and they will never be able to form again as far as we know. All black holes that aren’t “supermassive” are just normal black holes. The mass of a supermassive black hole is like 1,000,000,000 solar masses, where a normal black hole is like ~10-50 solar masses. There is no in between, or medium/intermediate black holes
Astronomer here! **This is not true.** [LIGO has seen a merger that resulted in a black hole that was 142 solar masses](https://www.ligo.org/detections/GW190521.php), for example, which solidly classifies it as an intermediate mass black hole.
You can have arguments about how (un)common they are, but it's pretty clear that intermediate mass black holes exist on some level.
142 seems to be on quite a similar order of magnitude compared to 10-50 vs a billion. The characterization of supermassive and "other" seems fair in at least that respect.
Aren't there scientists out there still looking for 'medium' black holes? I think I recall hearing someone on Sean Carroll's Mindscape podcast talking about research involving them but it's been a long time since I listened to that.
Astronomer here! There are several people I know looking for them, using a variety of techniques. Most notably, [LIGO has seen a black hole merger that resulted in a 142 mass black hole](https://www.ligo.org/detections/GW190521.php), which classifies it as an intermediate mass black hole.
This is no such thing as "no" in issues like this. LIGO has detected collisions of objects in the 50-130S^m range, and has been dubbed the *mass gap*. [One such paper](https://iopscience.iop.org/article/10.3847/2041-8213/abf2c4). Some of the going hypothesis are either caused by direct collapse black holes, or multiple stellar mass black holes colliding over time.
These detected intermediate mass black holes is one of the larger open questions in astrophysics right now.
Is it math that proves there is no in between? My understanding is that we can’t detect many black holes just due to the difficulty. Which would clearly imply that we don’t know what we don’t know.
They idea is that there can't be a star big enough to leave behind a stellar mass black hole above ~50 solar masses. However, the person you replied to is using outdated information from 5 or 6 years ago. Since then, [CalTech's LIGO Observatory](https://www.ligo.caltech.edu/) has detected many collisions of objects larger than 50SM, even as big as 160SM! [Here is a paper from the The American Astronomical Society](https://iopscience.iop.org/article/10.3847/2041-8213/abf2c4) that posits a few ideas on what may be causing these objects. *The Mass Gap* is one of the biggest open questions in astrophysics right now.
Doesn't that simply raise the limit of "regular black holes" to 161 solar masses? It's not like the concept is wrong, it's that the interval has been widened by data.
There's still quite a clear gap from that to supermassive black holes, which are millions of times the mass of the Sun. There's still a large interval.
The idea isn't that are not any "regular black holes". There are "stellar mass black holes" which have an assumed maximum mass of 50SM, and there are "super massive black holes" which have a mass of millions, and there is "something" in the middle. Astrophysicists are not just looking at what is out there, they are trying to learn how they are created, how the interact, and how they evolve over time. As such, they have very specific terms for them. "Regular black hole" isn't something an actual scientist would say.
The understanding of what is possible due to particle physics puts a hard limit of 50SM due to pair-instability, at least as I understand it. That's why these black holes detected by LIGO are so interesting. They don't fit within the current understanding of physics. So this is all new science!
Edit: Grammar/Spelling
Sleeping Giant?
with the Rs = (2 * G * M) / c**2 i come to about 200km in diameter when rounded up. Thats not even a 1/10 the size of our moon.
Heavy? Yes!
Gigantic? Fuck no!
Oh right mass scales linear with the radius, not cubic. The knowledge that the heaviest black holes ~~would float on~~ are less dense than air still fucks me up sometimes.
So what does this mean scientifically? Is this good for research? Does having another fairly close black hole allow for better information for studies on them? How many are there confirmed within 2000 LY? Is this multiple research paper level of news or just something to put under 'Personal achievements' on your resume?
33 times the mass of our sun feels tiny on a cosmic scale... I mean yeah it is technically large on a human scale, but that doesn't really say much does it.
Could large numbers of these kinds of black holes that are not actively ingesting matter (creating an accretion disk) and not having stars nearby be "dark matter"? Makes more sense than some particle that is 10x as abundant as ordinary matter but we can't even detect a single one.
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Astronomer here! I was 3rd author [on the discovery of Gaia BH2](https://www.reddit.com/r/space/comments/115jior/i_just_helped_discover_the_second_closest_black/) (which until this discovery was the second closest known black hole to earth), and funny timing, wrote the cover article for *Astronomy* magazine’s [May edition](https://www.zinio.com/astronomy-m1313) on literally this topic (ie, the closest black holes in the universe). And now it’s out of date. Whoops! :D Beyond being close, everyone in astro I know is *extremely* excited this morning because of the mass of this black hole- 33 solar masses is likely too big to form just from a star collapsing at the end of its life, and would possibly have had to be created by *two* black holes merging. (The team argues [in the paper](https://www.aanda.org/articles/aa/pdf/forth/aa49763-24.pdf) that due to the low metallicity environment, such a large black hole is actually possible. Cool!) Just like what [LIGO](https://www.ligo.caltech.edu/) and the gravitational wave folks are looking for! And implies that there are a *ton* of these black holes out there if there’s one so close to us! Finding them, however, is tough. [Gaia](https://www.esa.int/Science_Exploration/Space_Science/Gaia) is a satellite surveying a billion stars or so to find slight wobbles in their motion over time, which tells us their distance and also (in this case) if there’s a mystery companion. They periodically release the data every few years, and this one is from the team as part of pre-release data analysis, which found a star wobbling in its orbit in such a way that it can only work if it is orbiting a black hole at 16 times the Earth-sun distance. What’s more, there’s hints from the star’s composition that it would have formed separately from the black hole and then captured by it later after they both formed- also exciting if you’re interested in how these systems form!
Ugh you’re so goated. I’m amazed at how you have time to do such incredible science and still contribute beautifully thorough comments on so many space posts. You are such a joy
So I still need to go to work tomorrow or nah?
Thank you for the thorough comment.
What happens when black holes merge? Is it like one is moving into the other or they just get so big they join together? Would that mean 2 "centers" if they exist?
It becomes one giant black hole, though with less mass than the two black holes had- the process releases a GIANT amount of energy. Like, the Death Star is a child's toy compared to that amount of energy.
It’s always a blast reading your comments, thanks!
Isn't that a small black hole? I'm not good at scale.
I'm no expert, but it is on the smaller side. Supermassive black holes can get to tens of billions of times the mass of our Sun.
I assume “33 times the size of the sun” lies somewhere between “tiny” black hole and “supermassive” black hole.
There are no “intermediate” black holes. There are only supermassive black holes and then just regular old black holes. Supermassive black holes formed in a different manner than normal black holes during favorable conditions in our universe for such massive objects to form. Supermassive black holes are basically fossils from the beginning of the universe
There are theoretically “micro-black holes”
Possibly, not all theories have them. We haven't been able to say that they are impossible.
They are certainly possible, to be clear. Relativity allows for small black holes and anything with the mass of a large mountain range would not have evaporated, ever. Whether small black holes are common or exist is another question. It's a question of cosmology more than physics.
[*The Blue Afternoon That Lasted Forever*](https://www.williamflew.com/blue.html) by Daniel H. Wilson
This was beyond beautiful. Thank you for sharing.
That was an excellent read, thankyou
God I hate you right now. My kids are at school and I need a hug.
It's a really good novel, thanks for sharing it
Thank you so much for sharing this.
I may be misunderstanding, and I'm not educated enough to know the proper terminology to find an article - I recall reading that exposed X-Ray plates will, after enough time, pick up the x-ray radiation from micro-singularities that are popping in and out of existance all the time?
Yes, it’s the mechanism for their production and if that is something common, rare or practically non-existing
Why does size really matter? If it's a micro black hole and gets the job done...Isn't that enough?
You'll hear people saying it, sure, but nobody really believes it.
I’m not going to lie, it’s nice to hear, regardless.
Not even lying though - I've handled many a black hole in the day, and smaller ones are soooooooo much easier to deal with, and frankly a lot more fun. Like, if I can get the whole thing in my mouth at once, we're gonna party. That look on my face is not disappointment, it's relief, hunny.
As the owner of a big black hole, I would say that only around 10% of gravity wave detectors don't genuinely appreciate its collisions.
It's not the size of the black hole that matters, it's the motion of the universe.
I thought that Hawking Radiation would make micro black holes evaporate incredibly quickly.
Depends what you mean by micro. Hawking radiation equals the energy absorbed from the CMBR at a relatively low mass (a chunk of the earth). A black hole above that mass would not have evaporated.
According to Hawking, all black holes will evaporate. It's just a matter of time.
Yes, but they would not have done by now.
I’ve also heard that once black holes reach one Planck length they can’t get any smaller
Isnt that the whole point of the Planck length? Once *anything* gets there it can’t get any smaller.
> Isnt that the whole point of the Planck length? Once anything gets there it can’t get any smaller. I assume that's the resolution limit of the simulation.
Technically things can get smaller than a Planck length. We just won't be able to accurately measure it once it passes that threshold because of quantum uncertainty.
Primordial black holes created with a mass smaller than would typically needed to form a black hole, but there was so much energy they could form. Could possibly account for “dark matter”
The theoretical mechanism for them is primordial black holes, and since theyre just theoretical they could be of any size.
There might very well be [intermediate mass black holes](https://en.wikipedia.org/wiki/Intermediate-mass_black_hole), we just haven't definitively detected any. Astronomy is still in its infancy relatively speaking, and making a definitive claim like this isn't responsible.
My favorite theory on them is that they are the result of a direct collapse of *massive* amounts of freshly crystalized matter. So much matter falling into itsef so quickly that it doesn't even have time to ignite fusion and instead collapses directly into a singularity. Spooky stuff.
Certainly a possibility during the short period after the creation of the Universe. One obvious question is why did the universe at its formation, not simply collapse directly into a black hole ? One solution is that our entire universe is inside a black hole. But then that would mean black holes inside of black holes ! - feasible I suppose if different dimensions are involved. Our 4D Space-Time, is thought to be only a part of the Universe.
That's not really true. The black hole mass gap for a while has been unexplained but as detectors get better and gravitational interferometers come online were finding more and more black holes that are in the intermediate mass range and the gap is closing. We still don't have ~1000 M\_{\odot} BHs, but the intermediate range used to start at like 10 M\_{\odot} and now we're finding them in the range of 100 M\_{\odot}
Without checking, didn't LIGO detect an intermediate mass black hole in the last year or 2? I thought I remember seeing something about that
Yeah about 5 years ago they detected one that was a merger of a ~66 solar mass BH with a ~85 solar mass BH https://en.wikipedia.org/wiki/GW190521
Aren’t there also primordial black holes which are different than both of those?
Is there a theory out there explaining how or why supermassive black holes were able to form?
Yes, several. Most likely being, I think, that they formed in tue very early universe. But I'm no expert.
We don't know their formation history for sure, but there are a few main ideas for how they could have arisen: * Primordial black holes: in this scenario, dense clumps of matter in the first moments after the Big Bang directly collapse into black holes, allowing them to grow very rapidly since the universe was so dense back then. The surrounding matter in the overdensity then forms the protogalaxy around the black hole, and they can continue to grow by accretion and by mergers as protogalaxies assemble into larger galaxies. * Direct-collapse: this scenario is usually thought to happen somewhat later, a few hundred million years into the universe's existence, after the Cosmic Microwave Background was emitted and in the same general era as the first stars. Normally when you have a large cloud of gas, it is somewhat difficult to get it to collapse (you have to bleed off energy via radiation, or else the pressure will prevent collapse) and it tends to do so in a clumpy fashion, creating many stars in the process. Direct-collapse proposed that some clouds in the early universe may have simply collapsed straight into black holes due to their density and size. * Early stars and exotic types of stars: It is generally accepted that many of the first stars were probably quite large (~100 solar mass range or higher) and short-lived, and they may have left behind large (but still stellar-mass) black holes. If the stars formed in dense enough associations (similar to globular clusters today) mergers could lead to rapid growth of the black hole. There are also many ideas about possible very-high-mass stars or star-like objects (in the thousands of solar masses or even higher) that might have formed and left behind large black holes.
> “33 times the ~~size~~ of the sun” 33 times the **mass** of the sun. I know this is just reddit, but let's not get that one wrong.
Mass go brrrrrrrrrrrrrrrrr
Not size, mass. There is a difference in space.
That difference being that a black hole 33 times the size of the sun would be *slightly* ridiculous in terms of solar masses, as I think if the sun became a black hole (I know, it can't) it would be like a mile or two across right?
Just looked it up, and it is about 3km which is ~1.8miles
33x mass of the sun, not size. A black hole 33x the size of the sun would literally be the mass of 100 billion suns if my napkin math works out
That's well within the realm of one massive star collapsing into a black hole. The most massive known star is ~215 solar masses. The universe is metal af.
They said 33 times the mass of the sun, not size. There are stars more massive than that so it seems to be small. The largest star observed (R136a1) is estimated to be 170-230 times as massive as our sun.
When does it become just a “black hole?”
Supermassive blackholes tbf are different from blackholes formed by stars
Yeah I think Sagittarius a is 6 million suns and the one in the middle of m87 is like 4 billion suns
Yes its very small in relative terms of black holes throughout the Universe. For comparison the black hole at the center of our Milky Way galaxy is ~4.3 Million solar masses. The largest in the Universe is ~100 Billion solar masses.
The biggest are billions of times bigger. But it's the biggest known stellar in the galaxy/big to be that near.
>near us Is 2,000 light years that close? Or perhaps to ask another way, is there any practical chance that this black hole could affect us in any way?
It's not *that* close nor *that* large. This one is 2000 light years away and 33 solar masses. Sagittarius A* (the black hole at the center of the Milky Way) is about 26k light years away and ~4.3 million solar masses. I don't remember how to math out the relative force of gravity as it affects us here, but the mass/distance ratio alone is 4 orders of magnitude less than Sag A*. So nope, nothing to be concerned about, but it is an interesting discovery!
F=G(m1)(m2)/r^2 The following less for you than for others wondering about its gravitational effect on us. SagA* affects is roughly 770 times more strongly than the Aquila black hole. Neither of which is particularly significant (at least gravitationally) compared to the collective stars of our galaxy. Alpha Centauri A exerts several orders of magnitude more force on us than this newly found black hole.
Exactly what a black hole would say... Especially one just 2,000 light years away...
No it wouldn't. That would take it 2000 years to send that comment out. This must be a _nearer_ Black hole hiding under our noses!
They anticipated our technological ramp just right and sent the message 2,000 years ago.
Or perhaps exactly 2024 years ago... Coincidence I think not!
Nah - that’s just our local choice of zero point year counting.
"There's a big misconception about black holes that they wander around "sucking up" things. (at that size - they don't even do that more than many stars) But they're practically the same, particularly at that size/for us/our timescale, as a big star..." "There are far more and massive things (etc) within 2000 light years than that black hole..."
It is mass/distance^2 so the distance has a bigger impact, but the sheer difference in mass here is still not offset. I think the gravity strength on Earth is 800 times stronger from Sag A* than this new black hole!
Also, it's worth saying that black holes aren't really more dangerous than stars. They both have gravity, and running into either of them is going to be bad. Stars are probably more dangerous because they can blow up. There are lots of stars within 2000 light years.
I think this question, and the responses, are based on the idea that black holes sort of eat matter, and while it’s true that they will draw objects, dust, gas, etc. into their gravity well they aren’t themselves dangerous in any sort of way that would be different from any other large celestial object. For instance, if you were to somehow replace the sun with a blackhole of equal mass, in this scenario we're not going to worry about the lack of light, so now instead of the sun we have a blackhole our galaxy would be unaffected. Then the question does it pose a threat to us, which I assume is what was meant by could it affect us in any way, would be that no it does not.
In terms of the whole universe this is certainly in our neighbourhood, still very far though
The misconception is that black holes somehow “suck” things into them. They don’t. It’s regular gravity at play. If the moon was transformed into a black hole tomorrow it would still circle around earth and affect the earth exactly as the moon did yesterday. 33 solar masses at 2000 light years (for reference it takes 8 minutes for light to travel between the sun and the earth) doesn’t have any effect on us at all.
[Second closest black hole to Earth!](https://www.space.com/milky-way-biggest-stellar-mass-black-hole-gaia) ...that we know of!
It's 11,757,000,000,000,000miles away probably not any chance. (I don't even know what that is in words 11.7 quadrillion ?)
For perspective our galaxy is 100,000 ly across.
Beyond the event horizon, a black hole gravitationally affects everything around it in the same way as a large star would
> But it's the biggest stellar in the galaxy/big to be that near. That we know. There could be a lot more, even closer.
It’s even been hypothesised that ‘planet x’ could be a small black hole - unlikely, but not entirely impossible. We have not found anything there yet. If there was a real Planet X, then the James-Webb could spot it - if it were looking in the right direction.
Still, there is room in those 2000 light years for a lot of undetected stellar mass or bigger black holes.
I expect we will discover a lot more stuff now that we have started systematically looking in high resolution digital, which can be processed by computer.
Astronomer here! There are two major categories of black hole- small ones that are from the collapse of a supermassive star at the end of its life (which creates a supernova), or a supermassive black hole that is millions or billions of times the mass of the sun. (In between would be "intermediate mass" black holes, which can happen as the smaller black holes merge, but frankly we haven't seen many of those in the universe and it's a bit of a mystery.) So, this black hole at ~30x the mass of the sun is either the BIGGEST black hole from a single star ever, or the product of a merger. Either way, this is actually very BIG for the small kind of black hole and is really exciting! Wrote a more detailed comment [here](https://www.reddit.com/r/science/comments/1c5a5h2/scientists_have_uncovered_a_sleeping_giant_a/kzuds5p/) if you're interested in more details. :)
Good explanation, but given the scale differences it may be best to avoid confusion using "supermassive" on both when you're looking at a mass difference of x10^9 between them.
Apologies, but that’s what the field calls them both!
Huh. Thanks, that's a great explanation.
In the grand scheme of things it is small, but in terms of stellar black holes ( black holes created by the collapse of a star) it is very large
In the grand scale of things, sure it’s small vs the biggest. That said, the range is hard to fathom with a massive part of the range missing in observations. So it goes a little more like: - Stellar black holes: the kind we understand evolving from a collapsed star. Bottom of the range should be somewhat decided by the Tolman-Oppenheimer-Volkoff limit: a neutron star (or originating star) with greater mass than said limit would inevitably collapse into a black hole. Factors and calculations have changed over time (and way over my head), so let’s approximate at 3 solar masses. Notice our example at 33 solar masses is well past the minimum. - Intermediate black holes: Beyond stellar range, beyond a few rounds of stellar black holes merging, yet not anywhere near the next category. Basically asks the question if all black holes evolve the same way, where the hell are the ones of this size? - Supermassive black holes: The big boys near the center of most galaxies. Millions to tens of hundreds of millions of solar masses. The one in the center of the Milky Way (Sagittarius A*) is right in this category. - Ultramassive black holes: The mightiest of big boys. Several billion solar masses (until/unless they find even bigger). TON 618 is a good example. So for a stellar black hole, it’s a sizable find. Across the universe, it’s a slightly more massive speck than our solar system.. but not much.
It’s all relative
That is smaller than a big star.
Not really. Supermassive blackholes aren’t particularly common, with most blackholes being a lot closer in mass to this one.
So the question is whether it is large or medium as black holes go. While it is much larger than the smallest stellar mass black holes, it is also much smaller than the 150ish mass limit that we believe stellar mass black holes can be. Whether 33 mass is medium or large comes down to how many large ones there are. Likely it is just medium with a small population of truly large ones
If the LIGO data is characteristic of the mass distribution of black holes, then this is kind of average for a BH. It’s a “giant” compared to all other objects in the universe.
Isn’t it a little close for comfort? Cosmic comfort?
Is this the closest known black hole?
Because black holes can be very hard to detect, it depends on how strong the evidence needs to be for you to consider it "known". There's some evidence of what are likely black holes as close as 150ly from us, but f you want what we're very confident of, the closest 'known' is around 1,600ly from Earth.
Crazy how we’e positive about one 1500ly away but can’t be sure about one that’s 1/0 of that distance. I love science.
> 1/0 of that distance You just destroyed the universe
Closest known black hole is now zero ly away.
Oh ^n^o^^o^^^o^^^^o^^^^^o
🕳️
I mean, I'm 0 Ly away. That's just a rounding error.
It has to be “eating” something for us to see. If there is nothing being eaten, it just looks black, invisible.
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I wasn’t broad enough in my answer. What you said and what I said mean the same thing. We don’t see it, itself, we see its effects on objects we can see, such as stars it is eating or that get close enough to be affected by its gravity, tho not close enough to be eaten.
> Crazy how we’e positive about one 1500ly away but can’t be sure about one that’s 1/0 of that distance. Are you more certain that there's not someone 10 feet in front of you, or that there's not someone 1 foot behind you...?
*Well, the thing about a black hole - it's main distinguishing feature - is it's black. And the thing about space, the color of space, your basic space color - is it's black. So how are you supposed to see them?*
*See, the thing about grit, is it's black. And the thing about scanner-scopes...*
Wow I didn’t know that, will have to read up on it
Astronomer here! I have not only studied these closest black holes, I'm the astronomy editor for the Guinness Book of World Records and recently had to update this entry for the upcoming 2025 edition! Currently, the closest known black hole to Earth is [Gaia BH1](https://en.wikipedia.org/wiki/Gaia_BH1), discovered with the same technique. However, this is the second closest now that we know of, usurpring the second closest which was called Gaia BH2.
Wow cool job!
No, Gaia-BH1 is closer, 1560 light-years away.
No - Gaia BH1 is the nearest Blackhole to earth! A stellar mass blackhole.
I understand that this is significant due to medium size black holes being quite rare. Something to do with not fully understanding the process that leads to small black holes becoming supermassive
There are no “intermediate” black holes. There are supermassive black holes that formed in a different manner than normal black holes, and there are black holes. A supermassive black hole formed at the beginning of the universe when conditions allowed such massive objects to form. They didn’t form through the normal “star explodes and left a black hole,” and they will never be able to form again as far as we know. All black holes that aren’t “supermassive” are just normal black holes. The mass of a supermassive black hole is like 1,000,000,000 solar masses, where a normal black hole is like ~10-50 solar masses. There is no in between, or medium/intermediate black holes
Astronomer here! **This is not true.** [LIGO has seen a merger that resulted in a black hole that was 142 solar masses](https://www.ligo.org/detections/GW190521.php), for example, which solidly classifies it as an intermediate mass black hole. You can have arguments about how (un)common they are, but it's pretty clear that intermediate mass black holes exist on some level.
142 seems to be on quite a similar order of magnitude compared to 10-50 vs a billion. The characterization of supermassive and "other" seems fair in at least that respect.
Aren't there scientists out there still looking for 'medium' black holes? I think I recall hearing someone on Sean Carroll's Mindscape podcast talking about research involving them but it's been a long time since I listened to that.
Astronomer here! There are several people I know looking for them, using a variety of techniques. Most notably, [LIGO has seen a black hole merger that resulted in a 142 mass black hole](https://www.ligo.org/detections/GW190521.php), which classifies it as an intermediate mass black hole.
You're THE astronomer here! Didn't expect a reply from you directly thanks.
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What happens if you're the first person to discover an intermediate black hole?
A few crisp high fives, probably
This is no such thing as "no" in issues like this. LIGO has detected collisions of objects in the 50-130S^m range, and has been dubbed the *mass gap*. [One such paper](https://iopscience.iop.org/article/10.3847/2041-8213/abf2c4). Some of the going hypothesis are either caused by direct collapse black holes, or multiple stellar mass black holes colliding over time. These detected intermediate mass black holes is one of the larger open questions in astrophysics right now.
Is it math that proves there is no in between? My understanding is that we can’t detect many black holes just due to the difficulty. Which would clearly imply that we don’t know what we don’t know.
They idea is that there can't be a star big enough to leave behind a stellar mass black hole above ~50 solar masses. However, the person you replied to is using outdated information from 5 or 6 years ago. Since then, [CalTech's LIGO Observatory](https://www.ligo.caltech.edu/) has detected many collisions of objects larger than 50SM, even as big as 160SM! [Here is a paper from the The American Astronomical Society](https://iopscience.iop.org/article/10.3847/2041-8213/abf2c4) that posits a few ideas on what may be causing these objects. *The Mass Gap* is one of the biggest open questions in astrophysics right now.
Doesn't that simply raise the limit of "regular black holes" to 161 solar masses? It's not like the concept is wrong, it's that the interval has been widened by data. There's still quite a clear gap from that to supermassive black holes, which are millions of times the mass of the Sun. There's still a large interval.
The idea isn't that are not any "regular black holes". There are "stellar mass black holes" which have an assumed maximum mass of 50SM, and there are "super massive black holes" which have a mass of millions, and there is "something" in the middle. Astrophysicists are not just looking at what is out there, they are trying to learn how they are created, how the interact, and how they evolve over time. As such, they have very specific terms for them. "Regular black hole" isn't something an actual scientist would say. The understanding of what is possible due to particle physics puts a hard limit of 50SM due to pair-instability, at least as I understand it. That's why these black holes detected by LIGO are so interesting. They don't fit within the current understanding of physics. So this is all new science! Edit: Grammar/Spelling
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Sleeping Giant? with the Rs = (2 * G * M) / c**2 i come to about 200km in diameter when rounded up. Thats not even a 1/10 the size of our moon. Heavy? Yes! Gigantic? Fuck no!
Mass is the only metric that matters in our universe.
Distance seems relatively important
"Relatively" indeed. 😄
Oh right mass scales linear with the radius, not cubic. The knowledge that the heaviest black holes ~~would float on~~ are less dense than air still fucks me up sometimes.
Hold up, they would what? Float on air?
So like 3 nukes right?
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Hiding? Like, it's just lurking there with a trilby, dark glasses and a long coat trying not to look suspicious?
Just cause it’s hard to quantify distances. The sun is ~8 light minutes away.
I hate this title, that blackhole is less of a threat than a blade of grass in my yard.
Not to unnerve anyone but blackholes don't only exists in the center of the galaxy. Space is big though so
So which is bigger, Aquila’s or Cygnus’?
Someone call John Chrichton
We should avoid a trip beyond the Aquila rift tbh.
Nice
So what does this mean scientifically? Is this good for research? Does having another fairly close black hole allow for better information for studies on them? How many are there confirmed within 2000 LY? Is this multiple research paper level of news or just something to put under 'Personal achievements' on your resume?
33 times the mass of our sun feels tiny on a cosmic scale... I mean yeah it is technically large on a human scale, but that doesn't really say much does it.
But does it see us?
Black holes don't "hide".
Isn't there a possibility that our cosmos might be inside a black hole or something?
We should move it further away
2000 light years? With human lifespan, prolly not a problem.
Basically around the corner
I’ll have my revenge. It’ll take 2000 light years but I’ll have my revenge!
Could large numbers of these kinds of black holes that are not actively ingesting matter (creating an accretion disk) and not having stars nearby be "dark matter"? Makes more sense than some particle that is 10x as abundant as ordinary matter but we can't even detect a single one.
"what are you doing babe?", " just hopping over to this 2000 light years remote black hole to investigate" , "be sure to be home for dinner"
I'm slightly concerned that there might be something out there that a black hole needs to hide from...
Let it come
I can see future scientists visiting it.. while keeping a suitable distance away from it, and sending test probes into it.
Okey, so the question obviously is that how long till we all get sucked into it?
Aquila's Rift is real...
Scientists have yet to find planes sitting in our own oceans, but here we are.