Apple #24: Jupiter

Jupiter is my favorite planet. I like it because of the spot, which is a storm, and because it's lots of different colors. And, it turns out, all kinds of crazy stuff goes on there.


(Photo of Jupiter from Zabawiki)

• Jupiter is the fifth planet from the Sun.

• It is the largest planet in our solar system. It has more than twice the mass of all the other planets combined. If Jupiter were hollow, more than 1,000 Earths would fit inside it.

• Galileo's discovery in 1610 of four of Jupiter's moons and the fact that they rotated around Jupiter was the first time anybody realized that things in the heavens rotated around things other than the Earth.

• We now know of 63 moons that orbit around Jupiter.

• Jupiter is 90% hydrogen and 10% helium, with traces of methane, water, ammonia, and "rock." This composition is considered to be very close to that of the nebula from which our solar system was formed.

• The presence of "rock" is really only a guess. Scientists think that Jupiter probably has a rocky core, with a mass of about 10 to 15 times that of Earth.

• Around this core is liquid metallic hydrogen, which can exist only at pressures greater than 4 million bars.

• Winds whip around Jupiter at more than 400 mph, driven mostly by the planet's internal heat. This heat is generated by the planet's slow gravitational compression.

• The colors which seem to be on the planet are actually clouds, made mostly of ammonia and ice. The exact reason for the colors is uncertain. Some say they're from trace elements in the atmosphere, maybe sulfur or phosphorous. In some images, the colors are coded to correspond with altitudes of the clouds, where blue is the lowest and red is the highest.

• The Great Red Spot (GRS) is a 12,000 km by 25,000 km oval, large enough to hold two Earths.

• The Spot is actually a hurricane-like storm of gases, which has existed for at least as long as people have been looking at it, or over 400 years. Nobody seems to know much more about it than that. See a movie of the red spot in action.

• Jupiter also has rings, like Saturn, though they are much smaller and fainter. They were discovered by Voyager I in 1979. They are actually small dust particles.

• Jupiter also has "auroral emissions" or magnetic events like Earth's northern lights.

This is from the Hubble Space Telescope, in 2004:

Update: In July 2009, the telescope Hubble has taken pictures of a new large spot on Jupiter, a black one. It's estimated to be 6,000 miles wide, or about twice the size of Europe. This spot was probably caused, astronomers believe, by an impact from a comet or an asteroid.

To-scale image of the new black spot on Jupiter, as taken by Hubble.
(Photo from the Hubblesite)

While everyone has been talking about how great Hubble is for the pictures it's taken, the new black spot was first noticed by an amateur astronomer named Anthony Wesley from Australia.

Sources:
The Nine Planets
Views of the Solar System, Jupiter page
Hubble Space Telescope's Hubblesite
A little bit more detail about the Great Red Spot, from Astronomy 161, as taught by the Department of Physics & Astronomy at the University of Tennessee

News about the black spot:
"Hubble pictures Jupiter's 'scar'," BBC News, July 24, 2009
"See Jupiter's Great Black Spot," MSNBC News, July 24, 2009