Jupiter

Our solar system is pretty big. It used to be composed of nine planets, but we lost one to science, when they stated that Pluto was too small to be a planet, so now we have eight. I remember when some people believed that the asteroid belt was created from an exploded planet. That theory seems to have fallen out of favor. Today it is said that it is composed of extra material that was left over after the creation of the solar system. We can see the sun at the center and the planets circling around it. What do we really have though? I think that we should think of our solar system as composed of Solar System like structures. No there are no more suns in the solar system, only one, but some planets have more moons around them than the sun has planets. For the purpose of this article, I have focused in on Jupiter. Some think of this giant planet as a star that didn't make it. Right now there are 63 known moons circling this giant. The planet is so big, that several Earths could fit into the red spot that circles around Jupiter in its atmosphere.

To give you some idea of the size of Jupiter as compared to the Earth, the diameter of Earth in kilometers is 12,756, but the diameter of Jupiter is 142,984 km. The planet's diameter is over 11 times that of our planet. A day on Jupiter is only 9 hours long, because it rotates so fast. The planet is over 5 times further away from the Sun than the Earth is. Actually Jupiter does us a very big favor, it is so big and has such strong gravity, that it attracts many dangerous asteroids and thus protects the Earth. But Jupiter is the master of its own system of moons, some of which could even contain life. I am not saying that any of them have life, I am just saying that none of them have been fully explored yet and you never know what you might find.

When Galileo first pointed his telescope to the heavens he saw Jupiter and the four moons that now are referred to by his name, the Galilean Moons. They are Io, Europa, Ganymede and Callisto. They were sufficiently large enough to be seen even with his primitive telescope.

After the Galilean moons come a bunch of small ones. Some scientists think that many of the moons that are now orbiting Jupiter were meteors that were captured by Jupiter's gravity and now orbit the planet at different distances. Some of Jupiter's moons seem to be more interesting than others. Europa probably is of the most interest to NASA right now. It is believed that the entire moon is covered with ice and that if you dig down about 3 miles, you will possibly hit oceans. NASA feels that where there are oceans, there could be life. In 1995 the Galileo spacecraft took images and measurements of this moon. Europa is slightly smaller than our moon.

Io has been called one of the most exotic places in the entire solar system. I guess that one of the reasons for this is that it is very volcanic. As a matter of fact, it is the most volcanic place known in this solar system. Besides volcanoes that spew out lava to heights of over 16,000 feet, it has mountains that are 52,000 feet tall. Wow, watch out Mt. Everest. Io is bathed in electrons, protons and ions, due to its closeness to Jupiter. It is closer to that planet than our moon is to Earth.

Ganymede is the largest of Jupiter's moons and the largest moon in this solar system. It is larger than the planet Mercury, but has only half of its mass. It has a very distinctive surface, being composed of light and dark patches. Frost or ice is visible at the poles of the moon. There seems to be much water ice covering the moon. There are many craters on Ganymede, reminding us of our own moon.

Callisto is the last of the Galilean moons. This is also a large moon. It is approximately the size of the planet Mercury and is the third largest moon in the solar system. This moon doesn't have many features aside from impact craters. There are not even any mountains. The scientists that observed tests made by the Galileo spacecraft on its flyby have concluded that the moon has a crust about 124 miles thick and might have a salty ocean under that. Sorry, but I have to put this in the realm of wild guess. I think this is based on the low density of the moon, but maybe there is something inside the moon that we are not familiar with yet, or maybe there are large hollow areas that contribute to its low density?

Here is a list of Jupiter's Moons: