Jupiter becomes the planet with the most moons with this discovery!
Astronomers have discovered 12 new moons around Jupiter, bringing that planet's total count
to 92 moons.
The most significant number of natural satellites of any planet in our solar system.
How were these moons discovered, and by what names will they be known?
Let's find out!
" It is incredible that we are discovering satellites
on this gas giant 400 years after Galileo first observed Jupiter's four largest moons.
But the reality is that Jupiter is a planet that has always surprised astronomers with
the enormous variety of objects orbiting around it, artificial satellites larger than planets
(Ganymede), thousands of asteroids that share its orbit (Trojan asteroids), and a ring of
asteroids that it is not possible to see with telescopes.
Being such a massive body, it is expected that we discover new bodies orbiting around
it from time to time.
The discovery The new satellites were detected in March
2017 by a team led by astronomer Scott Sheppard of the Carnegie Institution for Science in
Washington.
The discovery was carried out with the Subaru Telescope, located in Hawaii, in addition
to the Victor M. Blanco telescopes, on Cerro Tololo and the Magellan telescope, both located
in the Atacama Desert in Chile.
In 2012 the Victor Blanco telescope was updated with a new 570-megapixel camera called DECam,
which allows observing very dim objects in space, such as asteroids or natural satellites
around giant planets such as Jupiter.
Sheppard saw the moons for the first time while looking for the hypothetical planet
9, which is believed to exist beyond Pluto; in a past video, we talked much more in detail
about Planet 9, and we recommend you see it.
While Sheppard was searching for the elusive planet 9, he observed an object passing in
front of the telescope, but it was not planet 9, but a much smaller object and also closer.
This object appeared to be very close to the asteroid belt, but as it measured its orbit,
it realized that it did not appear to be orbiting the sun.
The only objects that do not orbit the sun are two, the planets and the natural satellites
of those planets.
And since that object was not a planet, there was only one option, but before jumping to
conclusions, it was necessary to corroborate the information.
Why until now?
If the discovery of Jupiter's satellites was made in 2017, why did the news come out until
now?
The reason is that astronomers weren't entirely sure if they were satellites.
The main difference between asteroids and natural satellites is that asteroids orbit
the sun, while satellites orbit planets.
However, the line between asteroids and natural satellites is sometimes unclear, especially
regarding giant planets.
The images captured by telescopes in astronomical observatories are not high definition as you
imagine; they are points of light on a dark background; because of this, when astronomers
discover new objects in the solar system, they must first study them for a long time
to see their orbit, their trajectory, as well as their size and direction.
But the farther away it is from the object, the more difficult this process is.
The satellites discovered by Sheppard's team were no exception to the rule.
Once their data was taken, the information was sent to other telescopes, such as Magellan
at the Las Campanas Observatory in Chile, where they could corroborate this first object's
location.
To corroborate that it is a satellite around Jupiter and not an asteroid, the team must
observe the object for at least a year and corroborate its orbit.
The Minor Planet Centre, which operates at the Smithsonian Astrophysical Observatory
in Massachusetts under the auspices of the International Astronomical Union, is the organization
that confirms such discoveries in the Solar System.
After observing the objects for a long time and sending the information to the center
of Minor Planets, Dr. Gareth Williams pointed out that what Sheppard had observed were new
moons around Jupiter.
Retrograde satellites Astronomers initially suspected that the newly
discovered objects were satellites and not asteroids because they have a retrograde orbit,
meaning they orbit Jupiter in the opposite direction to the planet's rotation.
All eight planets in the Solar System orbit the Sun in the direction of the Sun's rotation,
which is counterclockwise when viewed from the Sun's north pole.
Six of the planets also rotate around their axis in this same direction.
The exceptions, planets with retrograde rotation, are Venus and Uranus.
Venus' axial tilt is 177°, rotating almost precisely in the opposite direction to its
orbit.
Uranus has an axial tilt of 97.77°, so its axis of rotation is roughly parallel to the
plane of the Solar System.
The reason for Uranus' unusual axial tilt is not known with certainty.
Still, the usual speculation is that, during the formation of the Solar System, an Earth-sized
protoplanet collided with Uranus, causing the skewed orientation.
Even known dwarf planets and dwarf planet candidates have orbits in the same direction
of solar rotation, but some have a retrograde rotation, like Pluto which has retrograde
rotation; Its axial tilt is about 120 degrees, so it rotates in the opposite direction to
the planets in much the same way as Venus.
In the Solar System, natural satellites typically have Prograde orbits; they orbit in the same
direction as their host planet, but many asteroid-sized moons usually have retrograde orbits.
This is because small satellites usually originate by gravitational capture; this means that
initially, the planets did not have these satellites.
At some point, an asteroid that passed near them was trapped by gravity and thus remained
orbiting said planet.
Because the asteroid can enter the planet's gravitational field from any direction, many
asteroids that become moons have a retrograde orbit relative to the planet.
All satellites with retrograde orbits in the solar system are tiny, except for one, Triton,
the largest moon of Neptune; it is the only natural satellite so large that it has this
type of orbit.
Astronomers believe that Triton was initially a dwarf planet like Pluto, but that, at some
point in history, it entered Neptune's gravitational field, becoming trapped as a natural satellite.
Asteroids can also have retrograde orbits concerning the Sun, although rare.
Comets can have this type of orbit; the most evident example is the famous Halley's comet,
which has this type of orbit.
The fact that 9 of the new moons discovered on Jupiter have this type of orbit gives us
an idea of how large the gravitational field of this planet is because it means that many
asteroids that have entered its orbit can no longer leave and they stay orbit the planet
in a retrograde orbit.
In addition to being very small, another characteristic shared by satellites with retrograde orbits
is that they are usually located very far from the planet.
For example, on Jupiter, the largest satellites orbit very close and in the same direction
as the planet's rotation.
Then there is another group of satellites a little further away that also orbit the
planet in the same direction.
But, they are usually smaller.
Finally, we have the smaller satellites that, due to their low mass and size, are located
in the farthest area; in this area is where they locate the satellites with retrograde
orbits.
The exciting thing about this is that although retrograde satellites have their zone around
Jupiter, there is one that ultimately leaves the rule because it orbits in the area of
retrograde moons.
But, with an orbit similar to those of the Galilean moons, it is in the same direction
as Jupiter's rotation.
So far, it is the only known moon to do this; scientists have temporarily given it the name
Valetudo.
This moon takes about a year and a half to travel around Jupiter, and its orbit crosses
the orbits of the retrograde moons in the opposite direction.
Therefore, scientists believe that there is a probability that this little "strange ball"
could cause a head-on collision with other satellites of Jupiter, which would be interesting
for science since head-on collisions would reduce objects to dust and be something never
seen before.
The discovery that small moons in different orbital groups are still abundant suggests
that the collisions that created them occurred after the era of planet formation.
In that phase, the Sun was still surrounded by a rotating disk of gas and dust that gave
rise to the planets.
Because of their size, between one and three kilometers, the new moons were most influenced
by this disk of gas and dust.
The Carnegie Institution for Science noted that if these materials had been present when
Jupiter's first moons collided to form today's moons, the drag exerted by gas and dust would
have been enough for the small moons to spiral toward Jupiter.
The moons' existence shows that they probably formed after this gas and dust dissipated,
which would mean that collisions between asteroids continued a long time later than we thought
until now.
How will they be baptized?
Jupiter and Saturn are loaded with tiny moons, considered fragments of once-larger moons
that collide with each other or with comets or asteroids.
The same goes for Uranus and Neptune, but they are so distant that they make it even
more difficult to detect possible moons; these are too small, usually a few kilometers; therefore,
astronomers rarely bother to name them.
Jupiter's newly discovered moons have yet to be christened, as half are less than 1.5
kilometers in diameter as if to justify a name.
However, Sheppard proposed calling the new "weirdo" Valetudo, named after the Roman goddess
of health and hygiene, great-granddaughter of the god Jupiter.
As an unnecessary but interesting fact, the name chosen by Sheppard is a tribute to his
hygiene-obsessed girlfriend who "showers several times a day."
In addition, he pointed out that it is likely that in the past, Valetudo was a much larger
satellite.
Still, by going in the opposite direction to the rest of the satellites, it has had
collisions that have reduced its size.
For now, the rest of the moons remain unnamed, but it is expected that they will be related
to Greek mythology and the god Jupiter if it is decided to name them.
What name would you give to one of these new moons if you had the opportunity?
Let us know what you think in the comments!