| While its clouds are Jupiter's most striking feature to the eye, they are thought only to exist at the very top of Jupiter's atmosphere, in a layer about 50 kilometers (30 miles) thick. In this region, the pressure in the atmosphere is comparable to that on Earth. Much in the way your ears feel pressure when you dive to the depths of a pool due to the weight of the water above you, the pressure inside Jupiter grows with depth in the atmosphere. Below the clouds, there is a 21,000-kilometer (13,000-mile) thick layer of hydrogen and helium. This layer gradually changes from gas to liquid as the pressure increases.
A Sea of Liquid Hydrogen
Beneath the liquid hydrogen layer is a 40,000-kilometer (25,000-mile) deep sea of liquid metallic hydrogen. Unknown on Earth, liquid metallic hydrogen forms under the extreme pressures that exist on Jupiter. At this depth, the pressure is more than three million times what it is at the surface of the Earth. Hydrogen molecules are so tightly packed that they break up and become electrically conductive. Scientists believe it is this electrically conductive liquid that causes Jupiter's intense magnetic field.
Jupiter's Core
Down deep, it's hot in there! The temperature at the core of Jupiter is estimated to be 30,000 degrees Celsius (about 55,000 degrees Fahrenheit). This heat makes its way up through Jupiter and shines through cloud-free holes in the clouds, which are appropriately named "hot spots". Possibly solid, Jupiter's core is estimated to be about one-and-a-half times Earth's diameter, yet ten to thirty times more massive. If there is a solid surface, one could not stand on it without being crushed by the incredible weight of the atmosphere above.
One of the by-products of Jupiter's ocean of liquid metallic hydrogen is a magnetic field stronger than that of any other planet. A compass used at Jupiter would point south rather than north as it would on Earth, meaning Jupiter's magnetic field is inverted compared to Earth.
The Magnetosphere
 The area surrounding a planet that is dominated by the planet's magnetic field is called a magnetosphere. Jupiter's magnetosphere is molded into a teardrop shape by the solar wind, the stream of charged particles blown out from the Sun — its point directed away from the Sun. If you could actually see Jupiter's magnetosphere from the Earth, it would appear to be several times larger than the full Moon.
Inside the magnetosphere is a swarm of energetic particles and gases. The low-energy ions, protons, and electrons are called "plasma." At Jupiter, the plasma within the magnetosphere tends to rotate along with its rotating magnetic field about once in 9 hours, blasting charged particles off of the surfaces of the moons as it sweeps by.
The Io Plasma Torus
 The Pioneers and Voyagers observed a giant doughnut-shaped collection of charged particles surrounding Jupiter at about the distance of the orbit of Io, which is now called "the Io plasma torus." Some of the material from the volcanoes on Io gets caught up in the rotating field and forms the torus.
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