Leicester University Physics Department

Jupiter

picture : Jupiter taken from Jet Propulsion Labs, NASA

Solar System Index

The Sun

Mercury

Venus

Earth

The Moon

Mars

Jupiter

Saturn

Uranus

Neptune

Pluto

The Kuiper Belt

Introduction

Being the fifth and largest planet of the solar system, Jupiter is almost as huge as a planet can be before becoming a star. This gas giant has many moons, new ones having been discovered quite recently.

Great Red Spot

Jupiter's Red Spot Jupiter's atmosphere is incredible to look at. Huge swirling patterns can be seen over the entire planet, and the study of them has indirectly helped scientists understand more about the nature of weather on our own planet. The Great Red Spot is, as far as we can tell, the most permanent weather feature in the solar system. It has existed for as long as it could be observed, and probably will for many more years. This picture of the Great Red Spot, courtesy of NASA, has a scale of several Earth diameters. In other words, you could fit several Earths into it at once!

Jupiter's Ring System

Jupiter's rings Although it is well known that Saturn has a ring system, it is not as commonly known that Jupiter does. In fact, all the gas giants do. The picture, taken by one of the Voyager probes (courtesy of NASA), shows one of the best shots of Jupiter's ring. It is made up of similar materials to Saturn's rings, but is far smaller and less spectacular.

Jupiter's Moons

Jupiter has several moons like all of the gas giants. The montage shown is of the four largest : Callisto & Ganymede at the top, and Europa & Io at the bottom. There are many other moons, but Ganymede, Io and Europa are by far the most studied.

The Galilean moons

Ganymede is the largest moon in the solar system, having a diameter of over five thousand kilometers, greater than that of both Mercury and Pluto. Its surface is a mixture of old, heavily cratered regions, and younger regions with lighter grooves and ridges. This is due to movements of the planet's crust in a similar way to earthquakes on the Earth.

Europa's surface is made of ice. It is extremely smooth, most visible markings being due to different surface compositions instead of craters and ridges, which suggests that it is quite a young moon, having been recently active. It is thought that that underneath Europa's surface there might be vast amounts of liquid water, making it the only moon or planet other than the Earth with more than trace amounts. It is believed that Europa has a similar structure to the Earth, and there is speculation that it could have a 'mantle' made of liquid water. Like Io, Titan and Triton, Europa has an atmosphere, the main constituent being Oxygen (which eliminates the possibility of all life as we know it, due to the lack of Carbon-based molecular gases). However, with the possible existence of liquid water deep under the surface, hopes of finding very primitive organisms have not been completely eliminated.

Io is by far the most volcanically active object in the solar system, as it undergoes tidal deformation due to orbital resonance with Europa and Ganymede. Europa completes one orbit for every two of Io's, Ganymede one for every four. At any time there are several active volcanoes here (one such is shown in the picture included, provided courtesy of the Planetary Data Systems, JPL), pumping out vast amounts of molten rock onto the surface, covering any craters which may have existed there. The pock-marked appearance of this moon led one NASA scientist to describe it as a 'giant pizza' when pictures were first received from the Voyager probes. Io is one of only four moons to have an atmosphere (none of them are breathable), the others being Titan, Triton and Europa.

Missions to Jupiter

Voyager probe In 1972, NASA sent the Pioneer 10 probe to Jupiter, allowing us the first views of this immense planet. It discovered the intense radiation belts, and proved that Jupiter was predominantly a fluid (gas and liquid) planet. This was later followed by Pioneer 11. Voyagers 1 & 2 (an artist's impression courtesy of NSSDC is included) followed the Pioneer program, allowing all of the gas giants to be studied.

The Voyager probes, being far more technically advanced, were able to study the features of Jupiter in far greater detail than ever before. To this day, the data obtained is still being analysed. On its way to the solar poles, the Ulysses probe used Jupiter's gravitational assist, allowing greater study of its magnetic features. The latest probe to complete a study of the planet was the NASA-run Galileo orbiter and atmospheric probe, which began its mission in December 1995 and ended in September 2003, when the orbiter finally spiralled into the planet. In its eight-year mission Galileo obtained stunning images of the Galilean moons as well as Jupiter itself, and also had a close encounter with the asteroid 243 Ida and its moon, Dactyl. The image above shows volcanic activity on Io at night, and was taken by Galileo (courtesy of JPL).

The Shoemaker-Levy 9 Comet Impact

Before 1992, comet Shoemaker-Levy 9 was just one of many that travel through our solar system. However, on July 7, 1992, on closest approach to Jupiter, the incredible forces experienced when that close to such a massive body tore it into many different pieces.

Disintegrated Shoemaker-Levy 9

The course change incurred by this break up meant that these fragments would again return two years later, colliding straight into Jupiter's atmosphere. Eugene and Carolyn Shoemaker, together with David Levy were the first to identify that the comet had indeed been split into so many pieces. The image of the comet provided is a much higher resolution image taken using the Hubble Space Telescope (courtesy of STSCI), and was one of many used to confirm what Levy and the Shoemakers had originally discovered. When SL-9 struck Jupiter between the 16th and 22nd July, 1994, massive atmospheric disturbances was created, allowing scientists far more insight into the atmosphere of the world. It also gave scientists data that allowed them to study more about the theories involved with high speed impacts, and fluid dynamics.