Jupiter – The Planet

Jupiter is the fifth planet from the Sun and is the largest planet in the solar system. If Jupiter were hollow, more than one thousand Earths could fit inside. It also contains two and a half times the mass of all the other planets combined.

It has a mass of 1.9 x 1027 kg and is 142,800 kilometers  across the equator. Jupiter possesses 62 known satellites. The four largest are Callisto, Europa, Ganymede and Io, and were named after Galileo Galilei who observed them as long ago as 1610. The German astronomer Simon Marius claimed to have seen the moons around the same time, but he did not publish his observations and so Galileo is given the credit for their discovery.

Jupiter has a very faint ring system, but is totally invisible from the Earth.  The atmosphere is very deep, perhaps comprising the whole planet, and is somewhat like the Sun. It is composed mainly of hydrogen and helium, with small amounts of methane, ammonia, water vapor and other compounds. At great depths within Jupiter, the pressure is so great that the hydrogen atoms are broken up and the electrons are freed so that the resulting atoms consist of bare protons. This produces a state in which the hydrogen becomes metallic.

Auroral emissions, similar to Earth’s northern lights, were observed in the polar regions of Jupiter. The auroral emissions appear to be related to material from Io that spirals along magnetic field lines to fall into Jupiter’s atmosphere. Cloud-top lightning bolts, similar to superbolts in Earth’s high atmosphere, were also observed.

Jupiter Statistics
Mass (kg) : 1.900e+27
Equatorial radius (km) : 71,492
Mean distance from the Sun (km) : 778,330,000
Rotational period (days) : 0.41354
Orbital period (days) : 4332.71
Tilt of axis (degrees) : 3.13
Orbital inclination (degrees) : 1.308
Magnitude (Vo) -2.70
Mean cloud temperature : -121°C
Atmospheric pressure (bars) : 0.7
Atmospheric composition:
Hydrogen : 90%
Helium : 10%