Jupiter is the giant of the solar system. Its mass is over two times that of all the other planets, moons, asteroids and comets put together.
All the inner planets (Mercury, Venus, Earth and Mars) are largely made of rock. Jupiter is the first of the gas giants. It mainly consists of hydrogen and helium. Unlike the inner planets Jupiter doesn't have a surface as such, just layers of cloud held together by the planet's gravity. When viewed through a small telescope it is possible to see dark stripes running parrellel to Jupiter's equator. These are caused by different belts of cloud in the Jovian atmoshere.
In a larger telescope, the Great Red Spot can be seen. This was first spotted by Giovanni Cassini in 1665 and appears to be a vast storm that has been raging on Jupiter for hundreds of years.

When looking at Jupiter through binoculars, it should be possible to see one or more of the Galilean moons. Discovered by Galileo in 1610 they are the four largest of Jupiter's satellites.
The smallest is Europa, which is slightly smaller than our own moon. Io is bigger than our moon and Ganymede and Callisto are both bigger than the planet Mercury. Astronomers are particularly interested in Europa because underneath it's icy surface there appears to be evidence of a warmer salty ocean. If this is the case then Europa could be our best chance of finding extra terrestrial life.

Jupiter Statistics
 Equatorial radius (km)71,492 
 Mean distance from the Sun (km)778,330,000 
 Mean distance from the Sun (Earth = 1)5.2028 
 Rotational period (days)0.41354 
 Orbital period (days)4332.71 
 Mean cloud temperature-121°C 
 Atmospheric pressure (bars)0.7 
 Atmospheric composition



With the unaided eye Jupiter appears as a very bright star.

With binoculars it should be possible to see one or more of Jupiter's largest four moons strung out along it's axis.
Viewed through a telescope you should be able to see the equatorial belts quite clearly. All the Galilean moons can be seen (providing they are not hidden by the planet). If one of the moons is moving across the front of the planet (called a transit), this may also be visible in a small telescope. The times of transits and the positions of the moons can be found in various astronomy magazines.

Return to Planets Page

Return to Home Page

Return to Home Page