Jupiter, the largest planet in our solar system


Jupiter is by far the largest planet in our solar system and is the fifth planet from our sun. It is about 318 times as massive as Earth. Jupiter is a gas giant, so it has no solid surface. Jupiter also has many moons ranging from rocky to icy to volcanic.

Jupiter is also featured in the movies “2001” and “2010” with Monoliths and the Hal 9000 computer.  If you’re a space geek you love those move.

How far away is Jupiter from Earth?

Jupiter is about 391 million miles from Earth and about 465 million miles from the sun.  It’s actually the fastest rotating planet in the solar system with each day lasting only about 10 Earth hours.  But takes about 12 Earth years for Jupiter to make it’s orbit around the sun.

What is a gas giant?

A planet is referred to as a gas giant if it has no solid surface and is composed entirely of gas. It is thought that Jupiter may actually have a solid core or possible the core is dissolved among the gas if it’s hot enough. Hydrogen and helium make up most of Jupiter’s mass.

The great Red Spot

There is this strange, large red spot that we can see on the surface of Jupiter. We don’t know exactly why it exists but appears to be a high pressure storm.  Is is thought to be composed of complex organic molecules, red phosphorus, or other sulfur compounds.  We do know it’s been around for at least 400 years since the first telescopes were able to observe the planet.

Jupiters Great Red Spot vs Earth
Jupiters Great Red Spot vs Earth

The red spot is very large, think of it like a very large storm, the size of two to three Earths!  Over time the red spot appears to be shrinking but we don’t know how long it may last.

Does Jupiter have rings?

Yes, in fact it has three main rings but are relatively faint and are difficult to see.  Voyager 1 first spotted the rings back in 1979 and further studied by the Galileo probe during the 1990’s.

The rings are made mostly of dust.  From the inside out they consist of an inner “Halo” ring, a thin “main” ring and two wide, thick and faint outer “gossamer rings”.

How many moons does Jupiter have?

Jupiter has a whopping 67 moons!  However the planet four largest moons (Io, Europa, Ganymede, and Callisto) are referred to as the Galilean satellites, after Italian astronomer Galileo Galilei, who observed them in 1610:

  • Io is volcanic and is fueled by gravitation tidal forces from Jupiter
  • Europa is very interesting because it is covered in ice and is thought to have a liquid ocean of water not far beneath the surface.  So much water in fact it would be about two times as much water as on Earth.  And where there is water they may be life!  The 2001 movie series, specifically the “2061: Odyssey Three” book, focuses on Europa has having intelligent life.
  • Ganymede is the largest moon in the solar system, even larger than the planet Mercury.
  • Callisto’s surface has many craters giving us a visible record into the past history of the moon