Astronomers announced the discovery of 12 new moons surrounding Jupiter. We're
going to learn more about those moons, and what they can tell us about the
formation of our solar system, starting right now. Hello everyone, I'm Christian
Reddy. your friendly neighborhood astronomer welcome back to Launch Pad,
where we help you to make sense of the universe and our place in it. If this is
your first time visiting us, please make sure to hit that subscribe button and
ring that notification bell so that you don't miss out on any new videos. Twelve
new moons were discovered orbiting Jupiter, bringing its total count of
moons up to 79. The moons were discovered accidentally. A team led by Scott S
Shepard of the Carnegie Institute for Science were using the Dark Energy
Camera, a 520 megapixel camera mounted to the prime focus of the 4 meter Blanco
Telescope in Chile. They weren't looking for moons around planets so much as they
were looking for a new planet in our solar system. Jupiter just happened to be
close to their camera's field of view and sure enough, they happened to detect some
objects that were moving over time. However, those objects were not moving
around the Sun. Instead they were moving around Jupiter. The moons were discovered
in 2017, but they take between one and three years to make one orbit around
Jupiter, so it took a full year before they could confirm the orbits and verify
that these were in fact moons of Jupiter and not some background objects. Two of
the moons orbit relatively close to Jupiter. They follow what are called
prograde motions. That means that they orbit the planet in the same direction
as Jupiter spins on its axis. The rest of the moons orbit much farther away from
the planet in a retrograde, or backward motion. And then there's Valetudo, a
real oddball of a moon because it orbits in the same region as the retrograde
moons, but follows a prograde orbit around Jupiter. This is like driving your
car at high speed down the opposite lane on a highway; not exactly a particularly
stable situation. Valetudo is named after the Roman goddess of hygiene and
cleanliness and is the great-granddaughter of the Roman god
Jupiter. But no matter how clean Valetudo keeps herself, she's probably not
long for this world, at least not in the grand scheme of things. A million or a
hundred years from now, Valetudo will almost
certainly crash into one of those moons and disintegrate. The outer moons most
likely formed as a result of collisions between once larger bodies that smashed
into existing moons around Jupiter long ago.
Valetudo may be the very last of these once larger objects. These moons are
really tiny, only about one to three kilometers across.
but Valetudo and the nine retrograde moons that were discovered with it tell
us something significant about when they formed. You see, when the solar system was
really young, it was filled with gas and dust everywhere. Had these moons been
orbiting Jupiter in those days, they would have been moving against this dust.
The dust would have caused drag forces on the moons and the moons would have
spiraled in much closer to Jupiter. So the fact that they are where they are
today even at this tiny size tells us that they must have formed after the
solar system's dust dissipated. So there you go! Jupiter has 79 moons - more than
any other planet in our solar system by a long shot.
Although I would not be surprised if we discovered yet more moons surrounding
Jupiter and indeed around other planets in our solar system as well. It just goes to
show that there's always something new to discover, even in our neck of the
universe. Now if you'd like to learn more about how our solar system formed, I have
a video on that. I also have videos on moons of our solar system and on the
giant planets themselves so feel free to check them out.
I'll make sure I've got some links for them in the description below. And if
this is your first time here, thank you again for watching and please make sure
to subscribe and ring that notification bell so that you don't miss out on any
new videos. Thank you so much for watching, keep watching the skies, and
we'll see you soon. [BEEP] ...interesting because....[birds tweeting ] AARRGHH, birds.
[BEEP]
[sighs] [birds keep tweeting]