
Twenty New Moons Found Orbiting Saturn - japaget
http://dtm.carnegiescience.edu/news/twenty-new-moons-found-orbiting-saturn
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typpo
Here's a visualization I made of the Saturn system with an option to highlight
the newly discovered moons:

[https://typpo.github.io/spacekit/examples/saturn/index.html](https://typpo.github.io/spacekit/examples/saturn/index.html)

Besides the 20 new moons, I find it interesting that there are 8 "lost" moons.
These are objects observed as far back as 2004 - but their current locations
are unknown.

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saagarjha
Is there a reason why moons don't seem to orbit above Saturn's poles?

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colechristensen
Conservation of angular momentum. Stars and their planetary systems form out
of clouds of dust and gas which collapse into a fuzzy disk and then into
bodies. The sum of the angular momentum before and after has to be the same so
there is a big statistical pressure towards all bodies rotation and orbital
planes to be near some average overall plane, there are gravitational forces
at work too. Orbits over poles are as far off plane as possible and so are
least likely.

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saagarjha
Then why don't they orbit in the same direction, as the planets do? Aren't
many moons gravitationally captured in any case?

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colechristensen
Gravitational capture is the only way retrograde orbits could happen - a blob
of spinning dust and gas just won't produce moons orbiting in opposite
directions. Anything going in the "wrong" direction will be subject to a whole
lot of drag forces and lose all of its orbital speed and fall inwards.
Retrograde orbits have to happen by grabbing something late or after the
formation phase.

All of the discovered retrograde orbiting moons are in similar orbits which
suggests they all came from some larger object broken apart. Keep in mind all
of these new objects are quite small, just a few miles across. About a billion
of them could fit inside Saturn's largest moon, Titan (seventeen were
discovered).

 _Regular moon_ fits with what I was talking about before.

 _Irregular moons_ are the ones with eccentric, retrograde, or otherwise weird
orbits and acquisition histories.

The more you get into specifics about this kind of thing, the less concise and
accurate you can be, it would take an expert up to date with the literature to
go much deeper.

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magduf
>Keep in mind all of these new objects are quite small, just a few miles
across. About a billion of them could fit inside Saturn's largest moon, Titan
(seventeen were discovered).

With planets, we started getting too many "planets" when we discovered more
and more really tiny ones, so we started coming up with new names for them:
"dwarf planet", "Trojan", "asteroid", etc. A small rock in the asteroid belt
orbits the Sun, but it still isn't called a "planet".

It sounds like we need to do something similar with moons, or else it's going
to get out of control. There's likely an absurd number of small rocks orbiting
Saturn and Jupiter; should they really all be called "moons"?

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perl4ever
"should they really all be called "moons"?"

Well, some of them are called "rings"...

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prewett
We had the Cassini spacecraft _in_ the Saturn system for 10 years, and in the
past two years we've found 32 new moons! We've found 67% more moons with
earth-based telescopes than we discovered actually being there. Wow, space is
big and we know nothing. (Of course, I don't think Cassini was actually
looking for new moons on the outskirts, but still, I'm surprised we didn't
accidentally find some of these...)

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m0skit0
Cassini's instrumentation was focused on studying surfaces, not finding moons
[https://en.wikipedia.org/wiki/Cassini%E2%80%93Huygens#Instru...](https://en.wikipedia.org/wiki/Cassini%E2%80%93Huygens#Instruments)

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kzrdude
A peeve I have would be to use a language of certainity ("has moons"):

> This brings the ringed planet’s total number of moons to 82, surpassing
> Jupiter, which has 79

When it's clear we don't have the absolute truth. We need to be humble. It's
clear then that Saturn has _at least_ 82 moons. Or maybe not even that, taking
account the "lost" moons mentioned in this discussion. Now we believe that
Saturn has about 82 moons.

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jcbrand
This is a problem with science reporting in general. Current theories or
observations are presented as absolute truth even though they're only
approximations of the truth based on our current data and understanding of
what's really going on.

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dimitar
Isn't the term moon devalued too much by now? Isn't there terminology to
classify these newly found 5km natural satelites differently from the massive
moons like ours, Ganymede, Europa and so on? Something like dwarf moons or
micromoons?

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benibela
Call them dwarf moons, until they have cleaned away the other moons

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carlob
I wonder when these are gonna go the way of Pluto: Saturn has n moons and a
shit-ton of dwarf moons. Wouldn't know where the threshold is though, because
something like Phoebe is an absolute outlier.

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taneq
That was my immediate thought - that the definition of ‘moon’ must have
recently changed.

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nsilvestri
Currently, the only way the definition of 'moon' can change is if it gets
defined at all.

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Razengan
It’s amazing that we still keep discovering so many new things in our own
neighborhood, and as another comment notes, still hard to keep track of things
as relatively close as Saturn’s “lost” moons.

This makes it kind of silly whenever we make confident assumptions about how
much of X or Y must be out there in the rest of the Universe.

(Not to knock the efforts of people who did accurately predict many facts
about faraway phenomena while being stuck on Earth.)

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xwdv
I wish they would open up the naming of at least one moon to whatever the
internet decides to come up with, rather than restricting it to the same old
boring gods and goddesses convention. That moon would probably become one of
the more popular celestial bodies in the solar system based on that alone.

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journalctl
“Today, class, we’re going to learn about Saturn’s newest moon, whose name the
district has forbidden me from actually saying.”

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AgentME
Think of all the confusion that could be caused if the voted name was actually
"whose name the district has forbidden me from actually saying".

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airstrike
Like setting your wifi password to "FOURWORDSALLLOWERCASE"

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perseusprime11
How come we are finding these new moons around Saturn just now? Did we not see
them before?

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kupopuffs
Nooo, my sci-fi novels!!

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Yuioup

      git commit -am 'Needs more moons'

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ForceOfPhil
Christopher Walken cowbell style Waow!

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dwoozle
Any notion of why the Earth has only one moon and other planets have hundreds?

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frabert
The Earth is miniscule in comparison to the planets that have hundreds of
moons. Those just have a stronger gravity field

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Yajirobe
What about Mars?

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dragonwriter
Mars has two itty-bitty moons, and the other two terrestrial planets have zero
moons. Earth’s moon has something like 99.99998% of the mass of all moons of
terrestrial planets.

