Asked by: Steevo Barker, Stevenage
Jupiter is often described as a ‘gas giant’, suggesting that it’s a huge balloon-like mass of hydrogen and helium, plus traces of other gases. In reality, the huge gravitational force of Jupiter crushes these elements to the point where they are anything but gas-like.
Lab studies have shown that the pressures expected within Jupiter cause an incredibly hot material called metallic hydrogen to form. Astronomers have confirmed the existence of a 40,000km thick layer of this stuff by analysing how the trajectories of space probes are perturbed as they approach. One such probe, Galileo, actually fired a probe into Jupiter’s clouds in 1995: it got just 150km in before disintegrating.