The Planet Jupiter - Facts, Information, & Pictures

Jupiter is one of the most interesting planets in the solar system.  It is a gas giant with storms that are larger than the planet Earth, a thick poisonous atmosphere, a diverse system of moons, and even thin, faint rings.  It is a great telescope target.  Jupiter rotates about every 10 hours, so from night to night, it looks different.   Most of the visible clouds on Jupiter are made of ammonia.  Strong east and west winds form the bands that are easily viewable in most telescopes.  Water has been detected on the planet.  Due to its thick atmosphere, we have not been able to peer at its core, but it is suspected to contain a small rocky core, possible the size of earth (which is miniscule compared to the overall size of Jupiter). 

Jupiter Cloud Motion

Jupiter has storm called the Great Red Spot (GRS) which is also visible in most telescopes.  the GRS has been raging for over 300 years.  It is about 3 times the size of Earth.  The Great Red Spot changes color from dark red to white to a dark pink.  The Great Red Spot is far from the only storm on Mars.  It just so happens to be the largest and most dynamic. 

Great Red Spot in Motion

Jupiter has an enormous magnetic field that is 20,000 times larger than that of Earth.  It extends almost 1 million miles toward the Sun.  The solar wind "pushes" most of the the magnetic field away from the sun and causes it to extend 1 billion miles behind Jupiter, reaching all the way to Saturn.

Jupiter also has a thin, faint ring system.  The rings were discovered by Voyager 1 in 1979.  The rings are only visible when the are lit from the back by the Sun, so they are only visible when you are on the other side of Jupiter relative to the Earth.  Thus, no Earth based telescopes can see the rings.

Jupiter has been visited by Pioneer 10, Pioneer 11, Galileo, Voyager 1, Voyager 2, Cassini, and most recently the New Horizons Spacecraft flew by on its way to Pluto.  Jupiter missions present a real challenge for spacecraft engineers due to the intense radiation it gives off.

Jupiter is almost a solar system unto itself.  Various spacecraft to have visited Jupiter have located a total of 49 moons!  The outer moons are most likely asteroids that got caught up in Jupiter's gravity and entered its orbit.  From ground based telescopes, we can see the four largest moons, Io, Ganymede, Europa, and Callisto.  They revolve around Jupiter rather fast and you can see them change position throughout the night.  Sky & Telescope has a great tool  to determine the positions of these four moons for any date and time. 

Jupiter's moon Io is the most volcanically active body in the solar system.  Jupiter's intense gravity tugs and pulls Io causing it to deform, heating up its core and causing volcanoes to spew throughout the moon.  The surface is a yellow color due to deposits of sulfur. 

Europa is a moon that is thought to be a large body of water (twice as much water as on Earth) encapsulated by a thin layer of ice.  The liquid water underneath the surface does not freeze because there is some heat source inside.  We can surmise that there is liquid water underneath the ice because of the cracks in the surface with water that flows up and freezes over creating new surface ice.  Astrobiologists are excited about the prospect of liquid water that may support life.  Life has been found in thermal vents on the bottom of the ocean on Earth, which may be similar to the conditions on Europa. 

Ganymede is actually larger than Mercury and is the largest known moon of an any planet.  Ganymede is thought to have a rocky core surrounded by a large amount of ice and topped off with a thin layer ice and rock mixed together.

Callisto's surface is littered with ancient craters.  There are no real defined layers on Callisto.  The moon is thought to be one big mixture of ice and rock.  A fine dust covers the surface of Callisto, including its craters.