The Idiot’s Guide to Everything: Jupiter

Posted on November 21, 2011




 In our solar system, there are eight planets. Eight planets of differing composition, interior and size. One of these planets absolutely dwarves the other seven on every possible scale. This planet is the 5th planet from the sun, Jupiter. If you were to combine the mass of Mercury, Venus, Earth, Mars, Saturn, Uranus and Neptune, double it, and then add a bit more, you would have the mass of Jupiter. Take a moment to properly take that in. Jupiter is more than double the mass of all the other planets combined. When you were in school and learning about the planets, from the diagrams you are shown you could be forgiven for thinking that Saturn and Jupiter are not far apart from each other in terms of size. This is not true. Simply put, Jupiter is the largest planet in our solar system, by a LONG way. It’s mass is 318 times that of Earth. Three Hundred and Eighteen. It is only around 10 times smaller than our sun.

 With a diameter of 88,850miles, Jupiter is 11 times wider than Earth. Despite being an average of 483 million miles from the sun, Jupiter is regularly seen in our night sky, being the 4th brightest object there. Through binoculars it appears clearly as a round disc, and even a small telescope will shows its cloudy outer layers. It has the fastest rotational period of any planet, with a day on Jupiter lasting less than 10 Earth hours, 9 hours and 50 minutes to be exact. A year on Jupiter lasts a total of 11.9 Earth years however. The diameter of the planet around the equator is 5,600 miles greater than the polar diameter also, giving it a sort of squashed look. This is due to its rapid rotation.

 Jupiter is the first gas planet encountered in the solar system, and is made up of 90% hydrogen and 10% helium. In fact, it is more like the sun than any other planet, and many scientists have theorised that it is actually a failed star. It is enveloped in a cloud atmosphere that is about 600 miles deep, with clouds of different composition forming throughout depending on temperature and pressure. There is no solid surface beneath the clouds, but it does have a rocky core that is 10 times the mass of the Earth. Electric currents within the planet create an incredibly strong magnetic field that stretches millions of miles into space, interacting with the sun’s solar wind as far as 7 million miles from Jupiter itself. This interaction with solar wind creates the beautiful colourful aurorae that have been photographed by the Hubble telescope on its poles. The gravity of Jupiter is so strong that scientists use it to accelerate spacecraft that are on their way to Saturn, Uranus or Neptune.

 The visible surface of Jupiter consists of swirling, distinctively coloured bands of clouds, which are constantly changing and form parallel to its equator. The dark bands are called belts, and consist of descending, warm gases, where as the lighter bands are called zones, and consist of ascending, cool gases. The colours range from red and brown to blue, depending on the compounds that they contain. Individual clouds features rarely last more than a few weeks on the chaotic planet, but some have been known to last for over a century. The most well known of these of course is the Great Red Spot.

 The Great Red Spot is found on the southern edge of the south equatorial belt. It is a viscous storm that rages anti-clockwise, and has been raging for over 400 years. It is larger than Earth. Unlike the hurricanes that are found on Earth, the Great Red Spot never comes over land, and it is driven by the internal heat source of Jupiter. It is believed to have absorbed weaker storms, which account for its size and longevity. It is shrinking however, and is half the size today that it was 100 years ago. It is colder and higher up than most clouds on Jupiter, sitting 8 km above the clouds. It makes a full anti clockwise rotation every 6 earth days. At the very edge of the storm the winds reach speeds of up 432 km/h. These sorts of massive storms are common on the gas giants of the outer solar system, but none are as well known as the Great Red Spot.

 Jupiter also has a faint ring of dust around 60,000 miles wide. One of the most fascinating aspects of Jupiter is its complex and vast system of satellites. It has over 60 known moons, which can be split into 3 groups. Most of these moons are small and faint, being less than 10km in diameter and only recently found, but it is the four Galilean moons that create the most interest. These moons are Ganymede (the largest moon in the solar system and bigger than Mercury), Callisto (similar size to Mercury), Europa (possibly the best hope for life outside of Earth in the solar system) and Io (the most geologically active celestial body in the solar system, with over 400 active volcanoes). These moons will be written about in a separate piece which will come once the planets themselves have been finished.

 Jupiter is named after the Roman father of the gods, the ruler of Olympus. Shockingly, Galileo was the first to view it through a telescope, at which point he also identified what would be termed the Galilean moons. Jupiter’s satellites are named after the lovers of Zeus, who is the Greek equivalent of Jupiter. The first recorded observations of Jupiter are from Babylonian times, and it has played a great role in Astronomy and even society ever since. The earliest known drawing of the Great Red Spot was made in 1831 by Heinrich Schwabe, a German pharmacist more known for his work on sunspots. It was first visited by Pioneer 10 in 1973, and since then 5 more probes have visited the planet, the latest of which is Galileo, whose mission ended in 2003 when it was deliberately steered into the planet. A spacecraft called Juno was launched in August 2011 with the aim of observing Jupiter’s poles, and it should arrive by 2016.

 Is there life on Jupiter? Extremely unlikely. However, as will be looked at further when talking about the Galilean moons, there are countless hypothesis regarding the harbouring of life on Europa. Jupiter itself however is far too violent a world to contain life as we know it. Whatever solid surface there may be underneath all of the vile swirling storm clouds would be under significant pressure, and there is also next to no water in its atmosphere. If an astronaut were to visit Jupiter, he wouldn’t make it past the upper storms.