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Seen all those pix of Jupiter from last night showing three or four of its moons?
Yeah, it actually has more. A lot more. A LOT lot more.
A new paper shows that Jupiter may have *600* moons bigger than about 1 km in diameter! https://www.syfy.com/syfywire/wait-jupiter-has-how-many-moons
Yeah, it actually has more. A lot more. A LOT lot more.
A new paper shows that Jupiter may have *600* moons bigger than about 1 km in diameter! https://www.syfy.com/syfywire/wait-jupiter-has-how-many-moons
2/ As of now, we know of 79 confirmed moons of Jupiter, ranging in size from Ganymede (bigger than the planet Mercury!) down to some about a kilometer wide. The small ones are faint and hard to spot, but a handful are known. A dozen were recently found. https://www.syfy.com/syfywire/a-dozen-new-moons-for-jupiter
3/ But more lie in wait. A set of images taken in 2010 was reexamined by astronomers, using a clever technique to help them find dimmer moons. In the end they found 45 new candidate moons. They need to be confirmed, but this indicates a LOT more are out there.
4/ Given how many they found, how big an area on the sky they looked, and how many their technique might have missed, they figure there are something like 600 one-km moons orbiting Jupiter, within a factor of 2 (so maybe 300 - 1,200). That's a lot of moons.
5/ It sounds like a traffic hazard, but space is big. Many of those orbit Jupiter 20 million km out, so plenty of room to move around.
Thing is, even though Jupiter is the biggest planet I doubt it has THE MOST moons. Another planet likely holds that title. Wanna guess?
Thing is, even though Jupiter is the biggest planet I doubt it has THE MOST moons. Another planet likely holds that title. Wanna guess?
6/ Neptune! Mind you we only know of 14, but that's because Neptune is so far away (4.5 billion km!). Small moons are too dim to see. But it's still a big planet, and more importantly *it's far from the Sun*. That's critical.
7/ There's a volume of space around a planet where the planet's gravity dominates over the Sun. A moon orbiting there can be stable for a long time. If it gets too far out the Sun pulls on it hard enough to yank it loose. It's called the Hill sphere.
8/ It depends on the mass of the planet and how far it is form the Sun. Neptune isn't as massive as Jupiter, but it's MUCH farther out, so its Hill Sphere is enormous, *twice* the radius of Jupiter's, so 8 times the volume. TONS more room for moons.
9/ Neptune has a couple of known moons that orbit it 45+ million km out. That's almost Mercury's distance from the Sun! The outer solar system is very roomy. Also, there are lots of iceballs out there called Trans-Neptunian Objects that could be captured by Neptune.
10/ If you're curious, I wrote a longer explanation of this on my newsletter:
https://badastronomy.substack.com/p/ban-257-political-analogue-astrogear
BTW this is why it's hard for moons to have moons. Their Hill Spheres are usually small because they're usually very near planets.
https://badastronomy.substack.com/p/ban-257-political-analogue-astrogear
BTW this is why it's hard for moons to have moons. Their Hill Spheres are usually small because they're usually very near planets.
11/ So while Jupiter having 600+ moons may be shocking, Neptune might have far more. Cool!
Finding Jupiter's moons will be easier though, so I hope dedicated searches look for them.
Finding Jupiter's moons will be easier though, so I hope dedicated searches look for them.
12/ The hard part would be naming them.
I suggest John, Maureen, Don, Judy, Will, Penny, Zachary, and B9?
#ThePainThePain https://www.syfy.com/syfywire/contest-pick-names-for-jupiters-new-moons
I suggest John, Maureen, Don, Judy, Will, Penny, Zachary, and B9?
#ThePainThePain https://www.syfy.com/syfywire/contest-pick-names-for-jupiters-new-moons
13/13 So as you gawk over the amazing and beautiful images and videos of the conjunction, remember, there's a LOT more there that you can't see. And we're not even sure how much more. https://www.syfy.com/syfywire/wait-jupiter-has-how-many-moons
