Jupiter

Jupiter is HUGE

More than 1300 Earths could be packed into Jupiter’s volume

It’s 318 times more massive than Earth

It has more than 2 ½ times as much mass as all of the other planets combined

It has a large mass, but it’s density is very low—this implies that Jupiter is mostly hydrogen and helium, with only a small amount of metal/rock (since it’s mostly gas, it’s called a gas giant—or, a Jovian planet)

What’s Jupiter made of?

Jupiter has three cloud layers

The first cloud layer is made of frozen crystals of ammonia, the second is ammonium hydrosulfide, and the third is mostly water vapor

Below the clouds, Jupiter has four regions:

helium and molecular hydrogen, helium and liquid metallic hydrogen, and a small, rocky core covered in an icy shell

Jupiter has no continents, islands, or any form of land—the only terrestrial/rocky stuff is at the core—but even that only accounts for 4% of Jupiter’s mass

The outer cloud layer

Jupiter has the fastest rotation of any planet—it rotates once every 10 hours

Jupiter looks striped because it is covered in belts of gas—these belts move east and west, causing the constant storms (like the Red Spot) on Jupiter’s surface

The Storms

The rapid rotation of Jupiter causes it’s outer layer of gas and ice to be covered in huge storms, like hurricanes

There are brown ovals and white ovals—brown ovals are warmer clouds, lower in Jupiter’s atmosphere, and the white ovals are cooler clouds, higher in the atmosphere

These ovals could last for hours, or centuries

The Great Red SpotThe Red Spot is a larger version of one of these oval storms

Because of the intense winds and rotation, it is always changing dimensions—right now, it’s 25,000 km long and 12,000 km wide (big enough to fit two Earths, side by side)

It was first observed in 1656, but there’s no way to know how long was there before that

It also has a daughter-storm—in the late 90s, three small white storms merged together to form a second red storm—Red Spot Jr. It’s much smaller, but similar to the Great Spot

One mystery about these red spots is how they got their color. How did three white storms merge to form a storm that later became red? The cause of the color is unknown

Formation of Red Spot Jr

The Liquid Layer

The enormous mass of Jupiter creates an intense amount of pressure—enough pressure to transform hydrogen in the atmosphere into liquid metallic hydrogen

This liquid metallic hydrogen can conduct electricity and heat like a metal, and so this entire liquid layer is full of currents of electricity

This electricity gives Jupiter a super strong magnetic field

The Core

The weight of Jupiter above the rocky core compresses the core into a sphere that has a radius of 10,000 km (Earth’s diameter is 12,756 km)

The core’s mass is equal to the mass of 305 Earths

The pressure of Jupiter’s weight forced light ice out of the rock and metal core, and created the icy shell, the barrier between the core and the liquid metallic hydrogen

But, theses ices should be liquid—the temperature at the core is 25,000 K (almost 4 times hotter than the surface of the Sun)

The moons—or, Jupiter’s harem

All 63 of Jupiter’s moons are named after the Roman/Greek god Jupiter/Zeus’ many lovers (and companions)

The four largest moons are Io, Europa, Ganymede and Callisto (these are called the Gallilean satellites)

Io and Europa are similar to Earth’s moon in size and density (meaning they’re rocky like our moon), and Ganymede and Callisto are similar to Mercury in size (BUT, their low densities imply that they are mostly water and ice…)

They are thought to have formed at the same time Jupiter was formed, from debris orbiting the planet

Each moon has its own unique composition and core

Io

Io has a larger density (3570 kg/m3) than Jupiter (1330 kg/m3), but obviously, its mass is much smaller—this leads astronomers to believe that Io is mostly iron and rock, more like Earth than Jupiter

It takes 1.8 days for Io to orbit Jupiter

Io’s coolest feature—it’s covered in almost 300 active volcanoes

These volcanoes have huge eruptions, and create lava that’s rich in magnesium and iron

But why so volcanic?Io’s volcanic activity is due to the numerous other moons orbiting Jupiter—their gravitational forces cause Io’s orbit to change distance from Jupiter

This put a lot of stress on Io, and actual causes the moon the “squeeze and flex.” This leads to increased friction in the moon, which increases heat

All of this heat brings gases and molten rock to Io’s surface, and eventually ejects them through volcanoes and geysers

If Io is one of Jupiter’s lovers, she is under a lot of stress from all of his other lovers—they are constantly vying for Jupiter’s attention, pushing each other farther away from the planet, and creating friction and stress in the process (and leading to explosions)

Europa

Europa takes 3.5 days to orbit Jupiter

Europa undergoes the same stress from the other moons that Io does—but in this case, the stress causes Europa’s surface to crack, and there’s enough heat created from this to keep the water in Europa’s crust in a liquid state

So, under the ice and rock surface of Europa is an actual ocean

Maybe Europa’s ocean supports life…

GanymedeGanymede is the largest satellite in the solar system—it’s diameter is larger than Mercury’s, but it’s density is much less

It takes 7.2 days to orbit Jupiter

Like Europa, it has an iron core, an underground, liquid water ocean, a thin covering of ice, and a thin atmosphere

Ganymede has two magnetic fields—the inner one is strong and permanent, and the outer one changes a lot. Jupiter’s magnetic field creates electric currents inside Ganymede, which creates Ganymede’s second magnetic field.

This could mean that Ganymede’s water might actually be salt water, because salt water is good at conducting electricity

The second magnetic field and implication of salt water support the theory of the ocean in Ganymede, and like Europa, might mean that the moon can hold life…

CallistoCallisto is the farthest moon from Jupiter

It takes 16.7 days to orbit Jupiter

Callisto also apparently has a liquid water ocean

But in Callisto’s case, the ocean is kept in a liquid state not from the stress of other moons, but from the heat generated by radioactive decay at the moon’s core

Callisto is super cold (it can get down to -315°F)

Callisto has a huge asteroid impact site, called Valhalla

This is important because the area around the site is much smoother than impact sites on Earth’s moon—the liquid ocean could have caused the asteroid to have less impact on the surface, supporting the theory of a liquid water ocean in Callisto

The other moonsThe other 59 moons are much smaller than the Gallilean satellites

The Gallilean moons, and the smaller moons that are closer to Jupiter, orbit the planet in the same direction of the planet’s rotation (called prograde orbits)

The moons on the outside rotate in the opposite direction (retrograde orbits)

Besides the many moons, Jupiter also has three ringlets (little rings), which are made up of dust particles and stuff that is ejected from Io

And besides the moons and the ringlets, there are two doughnut-shaped regions, composed of charged gas particles, that orbit Jupiter. These are called plasmas. One is the Io Torus, and the other one is in Europa’s orbit

Jupiter—the King Planet