Jupiter
Overview
Jupiter was named after the king of ancient Roman gods.
As the name aptly describes, Jupiter, the fifth planet from the Sun, is the king of all the planets in our solar system. It is a gas giant, and it is the largest of all the planets. In fact, its mass is more than twice of the combined mass of all other planets in the solar system.
Jupiter is composed of primarily hydrogen and helium, and most of Jupiter is in the form of liquid hydrogen. It is a huge ball of liquid hydrogen. Underneath the ocean of hydrogen, there is a relatively small core of molten rock and ice.
Jupiter would have become a star if it had been about 80 times more massive than it is now.
Galilean Moons
According to NASA, Jupiter has 53 confirmed moons and 26 provisional moons awaiting confirmation of discovery.
Among the confirmed satellites, four are large moons. They are Io, Europa, Ganymede, and Callisto (names of the Greek god Zeus’ wives). Galileo Galilei was the first to observe these four large moons (in 1610) using his newly invented telescope. The discovery of these four moons, orbiting another planet other than our Earth, helped Galileo defend his point that Copernican system of solar system was right. And that upended Ptolemy’s system of the geocentric universe.
What happened to Galileo, for supporting heliocentric theory, was a different story. You can read that sad story here. Now, these four moons are known as Galilean satellites.
One of the Galilean moons Ganymede is the largest of all the moons in the whole solar system; it is even bigger than the planet Mercury.
Another moon Europa may have ocean of liquid water under its frozen crust with life supporting ingredients.
Interesting Facts
Size: Jupiter’s radius is about 71,500 Kilometers. It is really a huge planet. We can fill Jupiter with 1321 earths. See how small the Earth looks next to Jupiter!!
Atmosphere: Jupiter has a thin (71 kilometers) gaseous atmosphere consisting of ammonia, ammonium hydrosulfide clouds and water vapor. Underneath the thin atmosphere lie the layers of molecular hydrogen, liquid hydrogen, metallic hydrogen and the possible core of silicate rock and ice, as the picture below shows.
Orbit: Jupiter takes 4333 earth days (about 12 earth years) to orbit the Sun. Its average distance from the Sun is 778 million kilometers. Sunlight takes 43 minutes to reach Jupiter.
Day and Year: Though it is a huge planet, its day is only about 10 hours. It spins on its axis extremely fast. Its year is 4333 earth days.
The Great Red Spot: The huge red spot on Jupiter is a shallow anticyclonic storm. It is bigger than our planet Earth and has been going on for centuries.
Life on Europa: One of the four big moons of Jupiter is Europa. As there is the possibility of liquid water below Europa’s surface, scientists speculate that organic molecules and life may exist in Europa. But there is no evidence for it so far.
Sources:
- The Cambridge Guide to the Solar System by Kenneth R. Lang, Cambridge University Press.