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*artist's
drawing |

average
distance
from the Sun:
about 778,000,000 km
diameter: 88.650 miles = 142,984 km
mass: about 1,899,000,000,000,000,000,000,000,000 kg
temperature: -166 C at cloud tops
number of moons: at least 63
any rings? yes, but they're really faint,
which is why you usually don't see them drawn in pictures
length of a year: 11.86 of our years
length of a day: only 9 hrs, 50 min, 28 sec!!!
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Jupiter is one of the Gas Giants. When
you see pictures of it - like the one we have on this page - you're
really looking at a thick layer of hydrogen and helium clouds that
completely cover the planet. If we would really want to try to see
Jupiter's surface, we'd have to send something through all those clouds
which are a few thousand kilometers deep. Jupiter, itself, is made up of
liquid hydrogen (see the next question) on the "surface."
Below this is liquid metallic hydrogen. There's none of this on the
earth! The center is chewy caramel - just kidding! The center is a big
chunk of ice and rock. |

Well, first of all, there's no surface
to stand on... You'd just have to swim around in an ocean of liquid
hydrogen. But the gravity on Jupiter is so strong that you'd sink
anyway. There's no oxygen to breathe or water to drink. So, the answer
is NO!


To escape Jupiter's gravity and get
out into space, a rocket has to travel at a speed of 134,118 mph or 60 km/sec. That's about
2063 times faster than your parents are allowed to
drive on a U.S. highway!

There are the Galilean moons
(discovered by Galileo): Io, Europa, Ganymede and Callisto.
The others are: Metis,
Adrastea, Amalthea, Thebe, Leda, Himalia, Lysithea, Elara, Ananke, Carme,
Pasiphae and Sinope.
In 1979, one of our flying robot
explorers, Voyager, took a picture of an ACTIVE volcano on Io! The lava
was shooting HUNDREDS OF MILES into space.
Europa has a surface made of ice and
scientists think there is an ocean underneath! This is the most likely
place in our solar system (other than Earth) for life to exist. There
are plans for us to have swimming robots explore this ocean. What a
great sci-fi movie this would make!
Jupiter is really huge! It's the
largest planet in our solar system. In fact, over 1300 Earths could fit
inside Jupiter! Now, that's big! Go
back up and look how long a day on Jupiter is. This is how long it takes
to make one full spin (like a 360 on your skateboard). How long? ONLY
ABOUT 10 HOURS?! That's the shortest day of any of our planets. So...
Jupiter is the biggest and spins the fastest. That's COOL! With all that
liquid metal spinning around really fast, Jupiter is a really big
magnet. 
The hottest
temperatures in our solar system (yes, even hotter than the Sun) occur
in Jupiter's magnetosphere. This is kind of like a big hallo
that the magnetic field makes around a planet. The temperatures here can
be a high as 300-400 million K. The center of the Sun (remember this is
the hottest part) is only 15 million K. Not only is Jupiter's
magnetosphere the hottest thing in our solar system, it's the biggest
too! It goes out past Saturn and you'd even be able to fit the Sun
inside of it.
Did
you notice that Jupiter is made up of the same stuff as the Sun? So, is
Jupiter hot like the Sun? It's magnetosphere sure is hot... But Jupiter,
itself, is not hot. The reason is that it just isn't big enough. For the
Sun, we told you that the Sun's heat came
from all the hydrogen atoms banging into each other. Because Jupiter is
a LOT smaller than the Sun, it just doesn't have a strong enough gravity
to get the hydrogen atoms running around enough. We
didn't used to think that Jupiter had rings. No one here had ever been
able to see any. That is, until 1979 (that's only a couple years after
Star Wars came out), when Voyager took some pictures of Jupiter
close up. It found rings! They are a LOT smaller that Saturn's rings.
(We left them off our drawing.) Did
you see the big red spot that we have in our picture of Jupiter? Well,
it's called the Great Red Spot. (Good name, huh?) It's a big storm
that's been going on for about 300 years! It varies in size and it's
sometimes as wide as three Earths!
Sources:
In Quest of the Universe, 2nd ed. by Karl F. Kuhn
Voyages Through the Universe, 2nd ed. by Fraknoi, Morrison and Wolff
Universe by Kaufmann
The Complete Idiot's Guide to Astronomy by Christopher De Pree and Alan
Axelrod
The Astronomy Cafe by Sten Odenwald |