so, we may have found our first moon orbiting another planet? http://advances.sciencemag.org/lens/advances/4/10/eaav1784
it isn't confirmed yet (much like between the first detection of an exoplanet {1988} and the first confirmed one {1992, or '95 if we're talking main sequence stars}, this'll take years), but the evidence so far is well in favor of the object in question being a moon instead of a planet and honestly I'm excited as hell for this?
sure it's literally the easiest possible object to find of its type (a neptune-sized gas giant orbiting a superjovian at a great distance), but the fact that we've found something like this at all is kind of amazing
also it's a fucking -small gas giant orbiting another, larger gas giant-. that may very well have formed in place. if that's confirmed that bodes super well for finding like, actual habitable moons around gas giants in the future
@Thaminga a gas giant orbiting a gas giant, I wonder if the smaller one also has moons and if so just how deep orbital mechanics will physically let you go. Moons orbiting moons orbiting moons.
@Felthry I could definitely see four steps down happening (massive, almost-brown-dwarf gas giant -> small gas giant -> Mars-sized rocky moon -> tiny asteroidlike moonlet), though that would take a pretty huge system to really work out and sheer luck to actually like, exist
maybe around like, a type A or B star
@Felthry better yet: make said star a brown dwarf
@Thaminga oh, of course!
Then put a space station in orbit around the smallest mini-moon, because hey, why not, maybe some aliens live on this world that surely has some _really weird_ weather conditions
@Felthry orbits like that won't affect weather conditions too much, I don't think!
now, astronomical events though? yeah those are going to be all sorts of fucked up
@Thaminga I mean, the sun would be periodically eclipsed by one of several larger bodies, I feel like that would do _something_ to the weather
@Thaminga Unless you somehow manage to have the planetary system at a very high inclination, but that's even _more_ improbable
@Felthry There'd definitely be some level of inclination at least, but yeah; eclipses like this don't actually last for long enough to affect the overall weather patterns too greatly!
@Thaminga A very high inclination is quite improbable though!
I wonder what it'd take to get a planet with a moon orbiting at near-90° inclination... it'd almost certainly have to be a captured asteroid or Oort cloud object, maybe even an extrasolar asteroid
@Felthry I didn't say high, but even low inclinations will radically decrease your chances of an eclipse; an object orbiting Neptune at the same distance the Moon has from Earth would already move three planetary radii above and below the planet at an inclination of only 10°; while this is high for regularly formed moons, remember that this is with respect to the -orbit-, and regular moons are typically coplanar with their planets' rotation axes (which can be well, anything).
@Thaminga Oh, good point. I didn't think about planets with highly inclined rotation axes.
@Thaminga @Felthry Now I'm wishing I'd taken screenshots of some of the buck-wild systems I've seen in Elite Dangerous (which claims to do a rough modeling of system accretion).
Here's one I found on a list of nearby Interesting Systems: https://www.edsm.net/en/system/bodies/id/20145/name/32+Cassiopeiae
@Felthry @Thaminga Go exploring and you can see some really beautiful things. Here's a (extremely remote) ring outpost in the Sadr Region nebula about 1.8kLY from Sol, with the North American and Pelican Nebulae in the background.
There's another screenshot from inside a planetary nebula that I haven't shared because I want to keep it *mine*.
@Thaminga Go one step further by having the biggest gas giant orbit the distal star of a binary star system