Robert’s Out of This World Space Odyssey: Jupiter, The Big Boy

Bring on the gas giants! And what better one to start with than the biggest planet in our solar system, Jupiter.


Jupiter is a big boy. In fact, it is so big that it Jupiter and its moons are basically a mini solar system within our own. When I say big, I mean big (compared to the other planets). It would take over 1,000 Earths to make something the size of Jupiter. Being so big makes it easy to see from Earth with the naked eye. Jupiter will be the second brightest planet in the sky (second to Venus). Because of its size, the ancient Romans named this planet after the king of their gods, Jupiter (the Greeks called it Zeus).

There is very little (if any) solid material on Jupiter – it is a giant ball of gas and liquid. It is comprised mostly of hydrogen and helium (more similar to the sun than the Earth), but there may be a very small solid metal core. If Jupiter was 80 times larger, it actually would have become a star and not a planet. Being so large also means it is the most massive (heaviest) planet, but since this weight is primarily Hydrogen and Helium (the two lightest elements), it is not very dense.

It takes this ball of gas 4,333 Earth days (about 12 years) to orbit around the sun. Jupiter can make one full rotation on its axis in 9 hours 56 minutes. That is faster than any other planet. Spinning so fast makes the center of Jupiter bulge out such that the diameter of the planet 7% larger at the equator than at the poles.

The average temperature of Jupiter (taken at the level we would consider ground level and also where any life would be, if there is any) is 70°F (21°C) – that is room temperature on Earth. Other than pleasant temperatures, the weather forecast on Jupiter calls for clouds and wind. The clouds are made of different chemicals that provide Jupiter with its fun colors. The high clouds of frozen ammonia are white and the darker blue clouds are found below them. The Great Red Spot is this planets most distinguishable beauty mark. It is a swirling spot of gas that is big enough for three Earths to fit inside of it. It really doesn’t move much and can shift colors from opaque to deep red (the color comes from small amounts of sulfur and phosphorous mixed with the ammonia crystals).

No giant planet wants to travel alone and Jupiter is no exception. This planetary rockstar has picked up a bunch of moons – 62 to be exact. The largest four, the Galilean moons (they were discovered by Galileo) are Io, Europa, Ganymede and Callisto. Jupiter is so big that it even has enough gravity to hold a comet in orbit.

A little known fact to most people is that Jupiter also has rings. That’s right, take that Saturn, you’re not the only one! Discovered in a picture taken by Voyager 1, the rings of Jupiter encircle the planet right around the equator. Jupiter has 3 faint rings that are made of tiny partials (similar to the size of particles in cigarette smoke). The main ring is around 20 miles (30 kilometers) thick and has an outer edge approximately 80,000 miles (129,000 kilometers) from the center of the planet.