Jupiter is the third brightest object in the sky after the moon and Venus. It has more than twice the mass of all the other planets combines. Its radius is 71,500 km. It would take more than 1400 earths to equal the volume of Jupiter. Jupiter exhibits differential rotation which means that its rotation rate is not constant from one location to another. It has the fastest rotation of any planet in the solar system. The rapid rotation has altered Jupiter’s shape. Due to the shape of Jupiter, astronomers have determined that it has a dense, compact core about ten times the mass of earth.
Jupiter’s atmosphere consist of a series of ever-changing atmospheric bands and the Great Red Spot. It is mostly made up of molecular hydrogen and helium. There is also small amounts of atmospheric methane, ammonia, and water vapor. Jupiter’s abundance of hydrogen and helium is due to its strong gravity.
Jupiter has many weather patterns. The Great Red Spot is a good example because it is a continuously existing spot of wind like a terrestrial hurricane. These storms, most of which are much smaller than the Red Spot, are common on Jupiter.
Jupiter has thirteen moons. The four largest moons are called the Galilean moons and the are Io, Europa, Ganymede, and Callisto. Io is the most active moon being the most geologically active object in the entire solar system. Its surface is a collage of reds, yellows, and blackish-browns due to the volcanic action on the moon. Jupiter’s magnetic field continually sweeps past Io and collects particles that the volcanoes spew into space. This causes the Io plasma torus which is a doughnut-shaped area of heavy ions that completely encircle Jupiter.
Europa, the smallest of the four Galilean moons is a generally young moon, maybe only a few million years old. Researchers believe so since there are relatively few craters on its surface. Its surface is made mostly ice that may be several kilometer thick and there may be a one hundred kilometer deep liquid ocean below it. There is evidence that in some places, water erupts and floods the terrain.
Ganymede and Callisto are the two outermost moons. They are not very dense which suggests that they have substantial amounts of ice throughout their masses.
Jupiter also has a ring that may be made up of fragments chipped off by meteorite impacts from the moons Metis and Adrastea.