If a Moon Has a Moon, Is Its Moon Called a Moonmoon?
A few years ago, an astronomer's son asked the type of question only kids and genius astrophysicists come up with: Can a moon have a moon? Juna Kollmeier of the Carnegie Institution Observatories couldn't answer her child's query, but she realized that investigating the idea could help answer questions about how moons form and even reveal some of the hidden history of the Solar System, reports Ryan F. Mandelbaum at Gizmodo.
The results, which she co-authored with astronomer Sean Raymond of the University of Bordeaux, were recently published in a short paper titled "Can Moons Have Moons?" on the preprint server arXiv.org, which hosts yet-to-be peer reviewed research. The study, however, has raised an even bigger question that now has the scientific Twitterverse riled up. Just what do you call the moon of a moon?
In their study, Kollmeier and Raymond looked at what would happen to a small submoon orbiting another moon. According to the paper, what they found is that in most cases there's just not enough space for a submoon to orbit another moon. Tidal forces would pull the little moon toward the host planet, ripping the mini moon to pieces.
For a submoon to survive, it needs to be small—about six miles in diameter or less. It also needs to orbit a large moon with enough gravity to hold it in place and must be far enough away from the host planet to complete its own orbit. It turns out that several moons in our own solar system fit the bill and could host submoons, including Titan and Iapetus, which orbit Saturn, and Callisto, which orbits Jupiter. Even our own moon is the right size and distance from Earth to potentially host its very own moon.
Also at ScienceAlert, Quartz, and Know Your Meme.
(Score: 4, Funny) by acid andy on Friday October 12 2018, @09:49PM (7 children)
Big moons have little moons upon their backs to bite 'em,
And little moons have lesser moons, and so, ad infinitum.
Yo Dawg! I heard ya like moons. So I put a moon on yo moon so you can surf while you surf!
If a cat has kittens, does a rat have rittens, a bat bittens and a mat mittens?
(Score: 3, Funny) by DannyB on Friday October 12 2018, @09:51PM (1 child)
So you're saying that moon's moons can have a moon. And those moons can in turn be mooned.
To transfer files: right-click on file, pick Copy. Unplug mouse, plug mouse into other computer. Right-click, paste.
(Score: 2) by acid andy on Friday October 12 2018, @09:55PM
Yeah, but if the moon is the moon of another moon, is the moon the moon is a moon of a metamoon?
If a cat has kittens, does a rat have rittens, a bat bittens and a mat mittens?
(Score: 2) by All Your Lawn Are Belong To Us on Friday October 12 2018, @10:10PM (2 children)
Moons all the way down, eh?
This sig for rent.
(Score: 2) by acid andy on Friday October 12 2018, @10:37PM (1 child)
Sure looks that way. But don't tell the turtles. They get terribly upset!
If a cat has kittens, does a rat have rittens, a bat bittens and a mat mittens?
(Score: 2) by DannyB on Monday October 15 2018, @02:00PM
That's no moon. It's a space station.
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(Score: 3, Touché) by maxwell demon on Saturday October 13 2018, @01:47PM
That sounds pretty lunatic. ;-)
The Tao of math: The numbers you can count are not the real numbers.
(Score: 0) by Anonymous Coward on Sunday October 14 2018, @12:32AM
Imagine a Beowulf cluster of that.
(Score: 1, Funny) by Anonymous Coward on Friday October 12 2018, @09:51PM (1 child)
Siphonaptera
by Augustus De Morgan
Big fleas have little fleas upon their backs to bite 'em,
And little fleas have lesser fleas, and so, ad infinitum.
And the great fleas, themselves, in turn, have greater fleas to go on;
While these again have greater still, and greater still, and so on.
(Score: 1, Informative) by Anonymous Coward on Friday October 12 2018, @10:23PM
(Score: 0) by Anonymous Coward on Friday October 12 2018, @10:15PM (6 children)
mooned?
moonies?
mooninites?
(Score: 0) by Anonymous Coward on Friday October 12 2018, @10:38PM (2 children)
Mor-Moons?
(Score: 2) by fishybell on Saturday October 13 2018, @12:21AM (1 child)
In accordance with recent revelation, they preferred to be called Members of the Church of Jesus Christ of Latter Day Saints.
(Score: 0) by Anonymous Coward on Saturday October 13 2018, @01:25PM
Surprised they're not called Moronists!
(Score: 2) by shortscreen on Saturday October 13 2018, @08:34AM
Chibi-Moon.
(Score: 2) by Unixnut on Saturday October 13 2018, @10:04AM (1 child)
Dwarf Moons
:-D
(Score: 2) by Unixnut on Saturday October 13 2018, @10:07AM
</plutorimshot>
(I didn't realise soylent stripped out the tags from plain text in the last post)
(Score: 4, Insightful) by black6host on Friday October 12 2018, @10:18PM (18 children)
Ok, first off, from TFA:
I don't think this is the first time this question has been asked. However, I do suggest the authors of this study do quickly head over to /r/theydidthemath :)
Actually, I find this stuff fascinating. Physics classes did that to me, it's not my fault...
(Score: 2) by takyon on Friday October 12 2018, @10:47PM (13 children)
1. Even if moonmoons rarely occur naturally due to the tight orbit constraints, we could potentially redirect asteroids into stable orbits around the Moon, Callisto, and Titan. All 3 of these moons happen to be decent locations for human habitats: the Moon for obvious reasons, Callisto because it experiences lower radiation than the other Galilean moons, and Titan due to its dense atmosphere.
2. The first exomoon MAY be a Neptune-sized object [soylentnews.org]. If it is far enough from its host planet, it could have substantially larger satellites of its own.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 2) by acid andy on Friday October 12 2018, @10:59PM (12 children)
Are there any benefits to us of doing this? Like, sources of minerals to the colonies below, some kind of orbital stepping stone or natural space station, or nudging them into a stable orbit to avoid a collision?
If a cat has kittens, does a rat have rittens, a bat bittens and a mat mittens?
(Score: 0) by Anonymous Coward on Friday October 12 2018, @11:08PM (1 child)
I guess you could post it as a status update on Facebook, or upload some pics to Instagram. But other than a social media distraction I don't think there's any real benefit.
(Score: 3, Funny) by acid andy on Friday October 12 2018, @11:17PM
You could write an article where you have to keep clicking through to see the 10 asteroids, with fresh ads by each one. Or is that too last decade?
If a cat has kittens, does a rat have rittens, a bat bittens and a mat mittens?
(Score: 2) by takyon on Friday October 12 2018, @11:28PM (9 children)
It might be easier to get the desired minerals and metals from asteroids. Titan is estimated to be half water, with a lot of ice and other junk near the surface.
Collision avoidance is definitely a good idea for near-Earth asteroids, since they are relatively accessible to us and we don't want them to hit Earth. Putting them into orbit around the Moon may be the politically correct option to avoid fears of causing a deliberate collision into Earth.
In all cases, putting the objects into orbit could make them easier to study, especially if there is a manned presence nearby.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 2) by realDonaldTrump on Saturday October 13 2018, @12:01AM (8 children)
There's an Asteroid coming. Shaped like a skull. They call it 2015 TB145. As in, To Be Determined. And they say it won't hit us. But maybe they're wrong. Who knows? Nobody knows. And SoylentNews Editors don't want you to know. Censored Sub!!!
(Score: 2) by takyon on Saturday October 13 2018, @02:23AM
Maybe I will chuck it in with the skeleton one, which is slated for Halloween.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 0) by Anonymous Coward on Saturday October 13 2018, @12:20PM (6 children)
Nobody knows? Only someone who is intentionally ignorant.
Read and remove your ignorance:
https://en.wikipedia.org/wiki/2015_TB145 [wikipedia.org]
http://www.minorplanetcenter.net/db_search/show_object?object_id=2015+TB145 [minorplanetcenter.net]
Oh, I'm sorry. "Ignorance is bliss" and you like it that way?
(Score: 2, Flamebait) by realDonaldTrump on Saturday October 13 2018, @07:11PM (5 children)
They don't know for sure. Nobody knows for sure what will happen. In life or in Space. And maybe you don't look at your Links. It says there. They call it "uncertainty." Fancy way to say, we don't know for sure!!!
(Score: 1, Funny) by Anonymous Coward on Saturday October 13 2018, @09:22PM (4 children)
How tall are you? Six foot 2 inches? Six foot one inch? Six foot 1.5 inches? Six foot 1.75023 inches?
They don't know for sure.
I look at the links. Not only that, I try to understand them. You may consider doing that.
Here let me get that [minorplanetcenter.net] for you:
What they are saying is that this orbit has a low calculated orbit uncertainty.
It's as if you launched a nuclear warhead at Tycho Crater [wikipedia.org] on the Moon, or even at a MoonMoon!
It might get a direct hit.
Then again, it might miss it by 10 miles. Maybe 20? Unlikely, but maybe 100 miles?
You are saying people cannot know for certain...
.... that it might actually hit the White House!!!
Yes, your statement is about that far off.
If ever a MoonMoon is found orbiting Luna, I hope they don't let you anywhere near the orbital calculations!
(Score: 2) by realDonaldTrump on Monday October 15 2018, @02:06PM (3 children)
Dumb tweet. Because nobody's seen the Skull for YEARS. So nobody knows what's been happening with it. What it's been doing. If you read the stories here -- they're saying, Planet 9. Otherwise known as Planet X. Is pushing things around with its Gravity. The planets, the asteroids -- many things. And possibly it pushed the Skull. NOBODY KNOWS.
Another thing, they had a story. The Farting Asteroid. Oumuamua. Not sure about the spelling. The media are constantly pouring over my tweets, looking for the misspelling. But, Oumuamua let out a big Fart. And it was like a rocket. Like a blast from a rocket. Maybe the Skull does the same thing -- NOBODY KNOWS.
The nuclear, we have the best nuclear of anybody. Except possibly for Israel. But it's not PERFECTO. If you look into the history of it, lots of things that didn't go the way they expected. Or the way they wanted. And if I use my Nuclear Button, possibly some of it will land in USA. It could land in Washington, on Trump International Hotel in Washington. Because it's something that our guys built. Regular guys that, at the end of the day, they go home to their families. And maybe a guy had a bad day, maybe he made a mistake. Or maybe he turned into a total nutjob. Or, maybe our nuclear has been hacked so ALL of it lands on us. So it comes back to us. And we won't find out until I launch it. I don't know. And you don't know. NOBODY KNOWS!!
(Score: 2) by martyb on Wednesday October 17 2018, @03:43PM (2 children)
Translation: I don't know (and really don't care) how scientists calculate orbits. Of course scientists, who have been doing this all their life, would NEVER think about measurement errors and how that might affect their calculations. Given a clear example of how much I do not understand things explained so that even a five year old could understand... ignorance is bliss and I want to be HAPPY!
As for the farting orangutan, that would be me. I ate at Taco Bell and those refried beans were really tasty, but... well you KNOW. It was, well, NUCLEAR! I can't say for sure, I might be wrong, but I'm pretty sure it was the beans. We need to get rid of those beans. Put them in orbit around the moon. All of them. Let them clump together under the POWER of GRAVITY! If we did that, then it would be a bean-moonmoon. But it would probably not last long. When that SKULL asteroid sees all those beans.. I tell ya, believe me, they are not going to last. It will gobble them up like CRAZY!
And those scientists who made mistakes. I tell ya, they never learn anything from their mistakes. They'd never think to make adjustments so they did not repeat past mistakes! And I should KNOW! I sure don't learn anything from my mistakes! No, the only thing that is PERFECTO is ME! People say I never lie. Never say anything unless I think it through and all the possible complications. Smart people! But I'm smarter! Stable GENIUS they call me! Well, some people do. NOBODY KNOWS! Trust me!
So believe me when I say that Skull asteroid COULD hit a MoonMoon!
Wit is intellect, dancing.
(Score: 4, Interesting) by realDonaldTrump on Thursday October 18 2018, @12:07PM (1 child)
Dumb tweet. And maybe you're being sarcastic. Or, maybe not. But, dumb either way. You don't read, or don't believe, the stories of SoylentNews. You think they're Fake News. And you're one of the Editors. So interesting. Really says so much!
9-11, remember the planes? Everybody thought, "oh, these planes are going to L.A. Or San Francisco." Well, they didn't go to L.A. And they didn't go to San Francisco. They were supposed to -- they didn't. They went to NYC -- and Pennsylvania. Because the guys driving them were VERY UNPREDICTABLE. But, I predicted the 9/11 attack on America in my book "The America We Deserve." I happen to think that they had not only a plane, but they had bombs that exploded almost simultaneously.
By the way, 40 Wall Street actually was the second-tallest building in downtown Manhattan, and it was actually, before the World Trade Center, was the tallest. And then, when they built the World Trade Center, it became known as the second-tallest. And after that horrible day, it became the tallest.
I said, look at the story about OUMUAMUA. That says, it's a rock. But it's also a rocket. It goes this way, it goes that way. Zigs & Zags. And nobody knows which way it will go. They call it, ASTEROID. And Space Skull is another one. They call it dead comet, it looks dead. Looks like a skull. But possibly it's not dead. And suddenly, Zig. Zag. And it goes somewhere UNPREDICTABLE. Like me!!!
(Score: 2) by martyb on Thursday October 18 2018, @07:59PM
Yes, my comment was intended to be funny, but I accidentally left off the "=)" smiley. My bad!
And... you got a genuine LOL out of me with that one. That got you a "+1 Funny" from me!
Wit is intellect, dancing.
(Score: 0) by Anonymous Coward on Saturday October 13 2018, @02:10AM (1 child)
Does it have to be a permanent "moon"? If not, then we have a working example, the Apollo Command/Service Module orbited the moon quite successfully while the lander went down to the surface and later partly returned.
https://en.wikipedia.org/wiki/Apollo_Command/Service_Module [wikipedia.org]
(Score: 2) by takyon on Saturday October 13 2018, @02:47AM
Maybe it doesn't need to be permanent to satisfy the definition of subsatellite, but it likely needs to be permanent or close to it if you want to actually find a naturally-occurring one. Iapetus may have evidence of a past one in the form of its ridge [wikipedia.org].
There probably are some subsatellites in our solar system, but they might be in between the size of a dust grain and a small room.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 2) by suburbanitemediocrity on Saturday October 13 2018, @09:15AM (1 child)
The Earth's moon has had many moon in the past. Even now I think it has a couple. It was a really dumb statement to make and show lack of thought. And yes, I took physics classes and know that three body systems are not stable, but for reasons, they can last a long time.
(Score: 0) by Anonymous Coward on Saturday October 13 2018, @10:35AM
Source? Not counting manmade.
(Score: 2) by bob_super on Friday October 12 2018, @11:54PM (1 child)
Gravity, how the fuck does it work ?
If the Earth, orbiting the Sun, can have a moon, Mars a few, and Jupiter well over 69 moons, can you tell me what part of gravity prevents a body orbiting around a planet from having a body orbiting it, the way we clearly see is possible when the main body is the Sun ?
(Score: 4, Informative) by bzipitidoo on Saturday October 13 2018, @03:22AM
Hill sphere and Roche limit.
Hill sphere is the maximum orbital distance of a satellite about a body without being perturbed and ending up in orbit about the larger body that the body orbits. Roche limit is the minimum orbital distance of a satellite that tidal forces won't be stronger than its own gravity and rip it apart. The Roche limit can be greater than the Hill sphere, which means there is no stable orbit for a satellite. The Hill sphere of a body can be smaller than the body, another case in which there is no stable orbit for a satellite. Most moons have the latter property.
If there weren't other bodies about, the Hill sphere of a body would be infinite. A planet could be orbiting the sun at a distance of 1000 light years or more, if the sun wasn't in a galaxy.
(Score: 1, Funny) by Anonymous Coward on Saturday October 13 2018, @02:07AM
The following really happened, science lesson c.1965, during the Gemini space program.
Sub: Now class, who knows what a satellite is?
Me: (sticks hand up)
Sub: You, carrot top--
Me: It's a smaller body orbiting around a larger body.
Sub: No, sorry, it's a moon.
Class: (snicker)
Me: (too stunned to say any more)
(Score: 2) by stretch611 on Saturday October 13 2018, @03:40AM
I suggest we call it a cheek.
After all, when I shoot the moon at someone, I usually do it with multiple cheeks.
Now with 5 covid vaccine shots/boosters altering my DNA :P