It's a good thing moons aren't a measure of
worth, because Jupiter would be the coolest thing floating. I mean, PLUTO has FIVE! We've got one. Just one measly little moon. A staple of alien worlds in science fiction
is multiple moons (or suns), because we lowly Earthlings have only ever had the one. The creation of which is a touchy subject,
but you can see more on that if you subscribe and check out my video on it; but why do we
keep living moonogamously while planets like Mars get to take both of their gals for a
spin? We only have one moon because of the way the
solar system was formed! There are two categories of planets, terrestrial
and jovian -- the terrestrial planets: Mars, Earth, Venus and Mercury; only have three
moons in TOTAL. Mars has two, Phobos and Deimos, and we have
one The Moon or Luna. Mercury and Venus are left all alone. Jovian planets, on the other hand, have scores
of moons! Jupiter has more than 60, Saturn also is over
that sextalunar threshold, Uranus has 27, and Neptune has 14. New Horizons is getting closer to Pluto as
we speak, and imaging Pluto's FIVE moons. FIVE. PLUTO IS A DWARF PLANET and it's swinging
with more moons than us. WTF pluto. We don't know the EXACT reason different planets
have different satellites -- the technical term for a moon -- but planets acquire satellites
through one of three possible ways. ONE, they get smacked by another body that
causes a chunk to begin to orbit; TWO, they capture it using their gravity to snap a passing
celestial body. THREE, they form alongside a planet from an
accretion disk. The first theory is likely how Earth got Luna
up there. The second explains Mars' moons. Mars is very close to the asteroid belt that
sits between the terrestrial and jovian planets; it could have easily grabbed its proto-planet-sized
satellites from there. It also may explain Pluto's five tiny moons. Pluto's smallest satellites, Nix and Hydra,
are little icy bodies which probably got too close and were trapped by Pluto's gravity. The accretion disks in the third theory, vogue
with the idea of solar system and planetary formation. As a solar system forms, dust gathers, spinning
into a disc. Eventually, gravity pulls the dust and gas
together, forming a planet, while any gas flying around the edge forms planetesimals
by coalescing around tiny chunks of ice, rock or flakes of metal or dust. Sometimes those planetesimals slam together
forming satellites -- which is probably how Jupiter got so many. Venus may have had a moon at one point, but
a paper from CalTech postulated the yellow planet suffered an impact which reversed its
spin, causing its moon to crash into its surface. Eventually, the satellite was absorbed and
it merged with the planet. Mercury has no moon because it's so small;
and although that didn't stop Pluto or Mars -- Mercury has the added difficulty of being
closest to the Sun. The solar wind is strong with all us terrestrial
planets, blowing away material that might have formed accretion disk planets, and affecting
satellites more than with jovian planets. The thing is, we only DISCOVERED other moons
existed when Galileo spotted Jupiter's four largest in 1610; these so-called Galilean
moons: Io, Europa, Ganymede and Calisto lit up astronomers' collective imaginations in
a fire still burning today. It was only in the 1970s that we finally confirmed
Mercury's LACK of moon, when scientists used instruments on Mariner 10 to peek at the tiny
planet. As we've learned more about satellites, missions
have been proposed to study them and not just their parent planets.