Star Talk - Jupiter, the King of Planets

Jupiter, the king of planets was named for the king of Roman gods. Jupiter is actually a title, or perhaps a term of endearment, meaning "Father Jove"...Jove is his proper name. It's appropriate that the planet is named for the greatest of the Roman gods, for it is by far the largest of the planets. If you took all the other planets and all of their moons, and all of the asteroids and comets, then doubled that mass, Jupiter would still be bigger. Our solar system is basically the Sun and Jupiter...everything else is crumbs and leftovers.

We know very little about the interior of Jupiter. We know the outer clouds are mostly hydrogen, helium, and ammonia ice crystals. We know the surface temperature is - 127 degrees C. and rises rapidly at depth. Only one probe, Pioneer, has penetrated the clouds, and it didn't last very long. As Pioneer got close, it encountered radiation levels more than 100 times greater than we expected. We have no idea why. Jupiter is assumed to have a core of molten iron. Above that is probably a vast sea of metallic liquid hydrogen. Then various layers of gases at increasingly cooler temperatures until we reach the surface cloudtops.

Jupiter spins at a very high rate. A day there lasts only 10 1/4 hours. Winds blow constantly at up to 28,000 mph. Vast storms with lightning far more powerful than we see here on Earth rage with incessant fury. It's the spin acting like a giant centrifuge that causes the clouds to form into the famous colored bands. It also causes the planet to bulge at the equator, which you can actually see in the telescope. Although it took form at the same time as the rest of the planets, Jupiter is so big that it's still collapsing and condensing. In doing so, it generates heat on its own due to the unbelievable pressure and density inside. Jupiter gives off about twice the amount of heat that it receives from the Sun. Could it eventually light off a nuclear furnace at its core and become a star? No, it would need to be 80-100 times more massive to do that. But it will get smaller, and denser, and eventually cooler. Just not in our lifetime.