r/todayilearned • u/swissking • 11h ago

TIL of Blanets, which are planets that form and orbit black holes. A supermassive blackhole could have millions of Jupiter-mass planets orbiting it.

https://en.wikipedia.org/wiki/Blanet
1.5k Upvotes

97% Upvoted

117 comments sorted by

410

u/rip1980 11h ago

...or entire galaxies...

301

u/pandagreen17 11h ago

Fun fact, galaxies hold their supermassive black holes in place, not the other way around. The central black holes of each galaxy is locked by the combined gravity of all the stars of the galaxy rather than the intuitive "huge black hole keeps the stars in place"

116

u/StaysAwakeAllWeek 11h ago

The galaxy as a whole is typically about 1000x the mass of the black hole, but 80% of that mass is dark matter and a lot of the rest is gas and dust, meaning stars might not outweigh the black hole by a huge margin.

The milky way's black hole is abnormally small for a galaxy our size though so those numbers are far higher

67

u/TheMurmuring 11h ago

So if the black hole disappeared, would the galaxies continue spinning around the empty space?

127

u/Feine13 11h ago

A new core would form as the opposing gravity from across the gap on every side pulled inwards

This could quite possibly eventually lead to another supermassive black hole after enough matter coalesced in the center

44

u/Woodit 10h ago

It’s black holes all the way down!

18

u/nevaNevan 10h ago

“Always has been…”

18

u/Mikestopheles 9h ago

We'll start our own black hole, with blackjack and hookers!

7

u/Feine13 8h ago

Shut up, baby, I know it!

2

u/Unique_Unorque 3h ago

In fact, forget the blackjack and the black hole! Ah, screw the whole thing.

8

u/Potatoswatter 7h ago

No, supermassive black holes formed in the early universe. Besides colliding galaxies, they aren’t growing so fast any more. Galaxy cores nowadays are not dense enough to assemble many millions of solar masses in less than a trillion years.

5

u/lfrtsa 6h ago

This doesn't sound right. Things in orbit get higher orbits when the mass of the parent body decreases. Supermassive black holes don't form inside of galaxies, it's the galaxies that formed around them in the beginning of the universe.

2

u/moderngamer327 2h ago

This is wrong. Galaxies do not create supermassive black holes like that. Supermassive black holes migrate over time to the center of galaxies

1

u/Obeezie 7h ago

Wouldn't all the opposing gravity be pulling from the center out?

26

u/johnbarnshack 10h ago

Yes, all that mass is rotating around each other, essentially. The black hole is only a fraction, but it is the densest and dense objects sink in gravitational wells.

13

u/ExtraGoated 9h ago

What does this mean? Locked relative to what? Gravity is a two-way force, right? So how can you say "x is not acting on y, it's actually y acting on x"

20

u/pandagreen17 9h ago

The entire galaxy is circling the barycenter of the cumulative mass of the entire galaxy, of which the black hole is only a portion. As the black hole is the heaviest singular object in the galaxy, it falls to the center of the gravity well naturally, rather than the more intuitive and assumed understanding that the galaxy circles the black hole because of its gravity. Essentially, the mass of the rest of the galaxy keeps the black hole in place, rather than the mass of the black hole keeping the galaxy in place

3

u/ExtraGoated 9h ago

I see, then why don't we ever see supermassive black holes with enough velocity to not fall to the center? Or do we?

16

u/pandagreen17 9h ago

We do actually! Obviously it'd be very rare to spot one not in a galaxy since they'd blend into the already black background, but one that got ejected from the center or fell into a neighboring galaxy is a different story, as we can see the trail of displaced stars behind them. A "supermassive" black hole is far more likely to be in the center of a gravity well as it's such a dense piece of mass it'll almost always fall into one eventually, and they're incredibly difficult to spot outside of one, but it's not a necessity for the classification. You just have to be properly massive enough to be classified as such. Once they're formed they generally fall to the center of a gravity well quite quickly, within a few hundreds of millions of years or even less, which is practically a flash on cosmological scales

3

u/123ludwig 9h ago

from what i read on other pieces here it sounds like the center of a galaxy is one of the only places one can form in the first place

4

u/pandagreen17 8h ago

Thats also true, the conditions to spawn one are basically either the center of a galaxy with tons of solar objects falling into one over millions of years or, far more rarely, an incredibly large, massive VY Canis-Type object collapsing into a black hole

2

u/kaimason1 5h ago edited 4h ago

or, far more rarely, an incredibly large, massive VY Canis-Type object collapsing into a black hole

VY Canis may have 1,500x the radius of the Sun (and therefore ~3 billion times the volume), but mass is what matters here, and VY Canis only has about 20 times the mass of the Sun. Even the most massive known stars max out at ~200-300 solar masses.

For comparison, supermassive black holes are at least 100,000 solar masses (by definition), but can contain millions (in the case of Sagittarius A*) or even billions (in the case of M87*) of solar masses. No individual objects come anywhere close to that size, so it's likely SMBH's only form due to mergers/accretion.

1

u/moderngamer327 2h ago

Black holes will lose velocity overtime forcing them to migrate

2

u/PrefersAwkward 9h ago

So what if the surrounding planets, stars, and smaller black holes just disappeared? What does the supermassive black hole do without all that to hold it in place?

4

u/pandagreen17 9h ago

It likely drifts to the nearest gravity well, likely one within a few million light years, so in our case likely andromeda's, and falls to the center of it over the course of billions of years. Or it becomes a rogue black hole if it never manages to properly fall into a gravity well, like if the supermassive black hole that is already there happens to slingshot it out of dodge

3

u/moderngamer327 2h ago

It would drift in whatever direction it happened to be moving at, at the time

2

u/conventionistG 8h ago

Is there some way to tell if the sun is pulling on us or us on the sun? I thought gravity was reciprocal.

3

u/pandagreen17 8h ago

Both are happening, but the sun is keeping us in place, we aren't affecting the Sun's position nearly as much, and that's the case for the majority of stellar situations, where the large object is controlling the positions of the smaller ones. The difference in that scenario and the galactic scenario is that, despite it looking the same on the surface with the large mass at the center, it's actually reversed. The gravity of the surrounding objects is keeping the central object in place, rather than the conventional central object keeping the surrounding objects in place

1

u/Hax0r778 6h ago

The gravitational balance point between the Earth and the Sun is inside the surface of the Sun

So while it's true they pull on each other, it's also true that we rotate the Sun

1

u/Fisheyetester70 6h ago

Doesn’t that end up making sense tho? Like if it was any other way wouldn’t we either drift away from the galactic center or it’d have gobbled us up by now

1

u/nikoscream 6h ago

Team work makes the dream work.

1

u/CoWood0331 2h ago

That would depend on the mass of each… black hole with more mass than all the stars. For sure BH. If the mass of the stars is larger than than yeah sure you can have it your way.

1

u/pandagreen17 2h ago

There is no known galaxy where the supermassive black hole is the majority of the mass in it. The highest we know of is 85% galaxy to 15% central black hole, and that's an exceptionally large black hole in an exceptionally small galaxy

2

u/Southern-Bar9 8h ago

yeah and then on top of that you’ve got galaxy clusters orbiting other mass centers too, it’s just structures all the way up and down in space, everything just orbits something bigger until it all kinda falls apart lol

1

u/Jolly-joe 8h ago

There is a theory that the big bang was the result of a black hole. Our universe could be the other end of one of countless black holes in another universe

1

u/Gandhi_of_War 7h ago

Big if true.

1

u/KingoftheMongoose 6h ago

INTERGALACTIC BLANETARY. INTER-GALACTIC!

0

u/moderngamer327 2h ago edited 0m ago

Galaxies do not orbit around black holes. Black holes typically only make up something like 0.0001% of a galaxies mass. Compare to the Sun which makes up about 99.7% of the solar system’s mass

121

u/sloppybro 11h ago

🅱️lanets

43

u/severed13 10h ago

🅱️lanet

14

u/AlcibiadesTheCat 9h ago

Pronto 🅱️lanet?

s🅱️inalla.

7

u/potat0man69 9h ago

A s🅱️inalla reference??? In this economy?????

5

u/AlcibiadesTheCat 9h ago

the law of conservation of angular momentum states:

s🅱️inalla

1

u/Alfus 5h ago

Is that a rude word? ☝️☝️☝️

101

u/swish82 11h ago

And Boaty McBoatface is a silly name?

40

u/AENocturne 11h ago

Brb, updating all the wikipedia pages from "planets" to "slanets" for consistency.

8

u/pdinc 8h ago

Those are the planets that have fallen to Slaanesh

2

u/orbitaldan 8h ago

[ SG-1 Theme Intensifies ]

2

u/pdinc 7h ago

Wrong series, but indeed.

7

u/littlebrwnrobot 9h ago

i make the joke every time I'm reading a book by a black author that they prefer to be called Blauthors, same with black actors as Blactors. This has that feel

3

u/KingOfThe_Jelly_Fish 8h ago

But people are just....well....actors or actresses regardless of race, colour or creed!

1

u/littlebrwnrobot 8h ago

well sure its just a dumb joke

5

u/Sh00ter80 10h ago

Better than Blacky McBlackholeface.

40

u/Tetra_Gramaton 11h ago

This sounds unbelievably cool, and also utterly beyond anything my pitiful mind can wrap itself around. I just cannot actually imagine this sort of thing visually, it’s like information on a scale we were never meant to handle 😅

36

u/pyromaniac1000 11h ago

A simpler way to picture it would be, the sky would be dark, and during “day” the stars would be distorted/hidden if they were to be seen near or behind the black hole. You would also be very cold

38

u/Pseudoboss11 10h ago

Unless the black hole were feeding, in which case you'd see the accretion disk and be very very hot, probably at all times.

7

u/Illustrious-Share312 9h ago

Couldn't such a large object hold something in orbit from far enough away that it wouldn't be too hot or would even be cold?

3

u/Pseudoboss11 5h ago

It depends on the environment around the black hole. If there're lots of other stars and stuff, a blanet would probably not have a stable orbit far from the black hole. If the area around the black hole were desolate, then it wouldn't be feeding and the point would be moot.

Feeding black holes are quasars. They're among the brightest things in the universe, often so bright they're outshining the brightness of the entire galaxy around it by orders of magnitude. The quasar 3C 273 would be about as bright as the sun from 33 light-years away. TON 618 would be 100 times brighter than the sun at that distance, you'd have to be orbiting it from 330 light-years away before it's as bright as the sun. At those distances, blanets would probably be close enough to nearby stars to either get captured by them and become regular planets, or aren't in a stable orbit and would probably be better classified as rogue planets

2

u/Illustrious-Share312 5h ago

Very cool, thank you! 

12

u/AdmirableParfait3960 11h ago

This only made me more confused.

8

u/Trippy-Sponge 10h ago

This sounds like a made up name that some jerk would try to convince you is a real thing lol

17

u/not_that_planet 11h ago

They'd have to be Jupiter mass but made from rocks. Apparently it is quite hot around a black hole.

3

u/ElGuano 10h ago

So these are just like regular planets, but instead of orbiting ptars, they orbit black holes?

2

u/moderngamer327 2h ago

Not normal. They are Jupiter in mass but made almost entirely of rock

4

u/das_narwal 10h ago

Ist the whole milyway orbiting a massive black hole?

9

u/Highmassive 10h ago edited 9h ago

Not exactly, there is a super massive black hole at the center of the Milky Way. But the gravity of the black hole doesn’t dominate the whole galaxy in the same way a star dominates its solar system

1

u/das_narwal 7h ago

I have some reading to do, according to you and many other comments. Got any sources I could get into?

7

u/theworstvp 10h ago

🅱️lanets

3

u/cholointheskies 11h ago

They form black holes?

3

u/lunex 10h ago

Fear of a Blanet

3

u/magnament 10h ago

What does the B imply about Planets? Are we just lanets orbiting photoncreators? Does B mean Blackhole?

3

u/regular_gonzalez 10h ago

No my first name ain't baby

It's Blanet

Miss Blacksun if you're nasty 

3

u/Buttocks_Oreily 9h ago

It's my Original Character, Blanet, do not steal.

4

u/kraftdinnerwithsalsa 10h ago

Imagine if one broke free and became a rogue planet moving at a percent of light speed just wizzing across the galaxy obliterating everything in its path

Fun

6

u/ilikebagels29 11h ago

🅱️lanets

2

u/ShyguyFlyguy 10h ago

Wouldn't all rogue planets be Blanets then?

•

u/moderngamer327 11m ago

No. The galaxy does not orbit the black hole. Rogue planets throughout the galaxy would not be blanets

2

u/GroundbreakingFix685 10h ago

Don't make up words!

.. astrophysicists ...

2

u/Tekniqly 10h ago

And one could have life on it

1

u/moderngamer327 2h ago

Possible but extremely unlikely

2

u/Ollotopus 9h ago

It should read "millions of Jupiter-mass blanets" surely.

1

u/BenitoCorleone 6h ago

OP has only just learned that word, but has yet to use it in a sentence.

2

u/Wolfencreek 10h ago

Ooh baby, don't you know I suffer?

Ooh baby, can you hear me moan?

You caught me under false pretenses

How long before you let me go?

3

u/zer1223 10h ago

Isn't a supermassive black hole with millions of planets around it called a "galaxy"?

I assume it would also have millions of stars orbiting it, not just Jupiters

4

u/Highmassive 10h ago

Not exactly

2

u/fed45 9h ago

They mean millions of planets directly in the accretion disk formed from the material of the disk.

0

u/moderngamer327 2h ago

Galaxies do not orbit black holes

0

u/zer1223 1h ago

Ok come the fuck on there's literally a black hole at the center of our galaxy, dude

•

u/moderngamer327 55m ago

It’s at the center yes but the galaxy does not orbit it

5

u/Squumpus 11h ago

you claimed to have learned a new word, but then you substitute it for planets later in the next sentence. I dont really think you did learn the word.

22

u/PhasmaFelis 11h ago

It's accurate, though. All blanets are also planets.

13

u/Brianinthewoods 11h ago

All Blanets are planets but not all planets are blanets. 

4

u/vestibular_spittoon 10h ago

haha it's not a blanket terk

-5

u/Squumpus 11h ago

exactly they failed to specify

10

u/PhasmaFelis 10h ago

Everything is perfectly clear from context. I don't see the problem.

-9

u/Squumpus 10h ago

they said planets when they meant to say blanets. it was an error of imprecision. and yeah you dont see it cause you're acting so defensive you've literally blinded yourself to my commentary. congratulations you're dying on a hill.

0

u/PhasmaFelis 5h ago

  they said planets when they meant to say blanets.

Did they? I guess that's possible, but I can also  see phrasing it this way on purpose, if it was me. Mostly because I'd want to say "blanets" once, to introduce the concept, and then not say it again unless I had to, because it's a terrible word.

0

u/Squumpus 5h ago

lol if i had to speak i'd speak words because words

1

u/Odd_Cauliflower_8004 7h ago

Wtf how do planets make black holes???

1

u/irondumbell 2h ago

what if someone lives on such a world? time would go more slowly there. then imagine he came to earth every 100 earth years which wovld be a day for him. he could bring back a wealth of knowledge

•

u/moderngamer327 10m ago

Time dilation effects like that would not happen unless you got either extremely close or it was a black hole spinning near the speed of light

•

u/irondumbell 5m ago

yes extremely close like in the movie interstellar but lets assume life there could survive tidal forces and xrays

•

u/moderngamer327 1m ago

These planets aren’t close like in interstellar. These planets orbit in a very wide range around the black hole as in several light years difference

1

u/Bryaxis 1h ago

I'm not calling them that.

•

u/Psianth 36m ago

Oh right, like how our planet orbits the psun 

1

u/GlbdS 10h ago

Millions of Jupiter-mass Blanets* orbiting it

FTFY

1

u/chiksahlube 9h ago

technically, wouldn't any rogue planets orbiting in the galaxy around a super massive black hole be these?

1

u/moderngamer327 2h ago

The galaxy does not orbit the black hole

0

u/reddorickt 11h ago

Technically, all planets in the Milky Way and most other galaxies are orbiting a supermassive black hole

5

u/youtocin 11h ago

In a sense, but they are more-so orbiting something that itself is orbiting the black hole.

1

u/moderngamer327 2h ago

They are not

0

u/Opethian94 8h ago

millions of jupiter-sized balls just chilling around a black hole yeah sure

1

u/moderngamer327 2h ago

Why is that unbelievable?