Named after the Roman king of the gods, Jupiter is fitting of its name. With a mass of 1.90 x 1027 kg and a mean diameter of 139,822 km, Jupiter is easily the largest and most massive planet in the Solar. To put this in perspective, it would take 11 Earths lined up next to each other to stretch from one side of Jupiter to the other and it would take 317 Earths to equal the mass of Jupiter. It is the largest and most massive planet with the fastest rotation.
Jupiter has the shortest day of the eight planets. Jupiter rotates very quickly, turning on its axis once every 9 hours and 55 minutes. This rapid rotation is also what causes the flattening effect of the planet, which is why it has an oblate shape.
One orbit of the Sun takes Jupiter 11.86 Earth years. This means that when viewed from Earth, the planet appears to move very slowly in the sky. It takes months for Jupiter to move from one constellation to the next.
Jupiter has a faint ring system around it. Its ring is mostly comprised of dust particles from some of Jupiter’s moons during impacts from comets and asteroids. The ring system begins about 92,000 km above Jupiter’s clouds and reaches more than 225,000 km from the planet. The rings are somewhere between 2,000-12,500 km thick. The view from Jupiter is murky at best. Don’t buy Jovian real estate for the view.
Jupiter has at least 67 moons in satellite around the planet. This includes the four large moons called the Galilean moons that were first discovered by Galileo Galilei in 1610. The largest of Jupiter’s moons, Ganymede is the largest moon in the solar system. Ganymede is larger than the planet Mercury with a diameter of around 5,268 km.
Jupiter has a very strong magnetic field. This is around 14 times stronger than the magnetic field found on Earth – the largest of any planet in the solar system. This is the reason why Jupiter pulls meteors and other planetary debris away from Earth toward itself and its moons.
Jupiter has a very unique cloud layer. The upper atmosphere of the planet is divided into zones and cloud belts which are made of ammonia crystals, sulfur and a mixture of these two compounds.
Jupiter does not experience seasons like other planets such as Earth and Mars. This is because the axis is only tilted by 3.13 degrees.
Eight spacecraft have visited Jupiter so far. Those are Pioneer 10 and 11, Voyager 1 and 2, Galileo, Cassini, Ulysses and the New Horizons mission. There are also plans for future missions to focus on the Jovian moons of Jupiter – Europa, Ganymede and Callisto.
THE RED AND BLUE SPOTS (SEE PICTURE ABOVE)
The “red spot” is a gigantic hurricane of ammonia gases that has been raging for at least 300 years. A giant red spot was seen on Jupiter in the seventeenth century, when telescopes first started to be used. However, it is unknown whether this is the same red spot that we see today, or whether Jupiter has had many such storms that have come and gone as the centuries pass. The red spot circulates anticlockwise and takes six (earth) days to rotate completely. Another mystery surrounding the red spot is what makes it red: scientists have come up with several theories (for instance, the presence of red organic compounds) but as yet nobody knows for certain.
The “blue spot” is an aurora.Recently the Hubble Space Telescope captured an amazing event on the North Pole of Jupiter. As you can see from the image above, Jupiter, like Earth, has an Aurora ( Northern Lights ) which instead of a mystical green like on Earth, appears to be an electric blue colour.
Those layers of the atmosphere visible to Earth-based telescopes are divided into lighter and darker horizontal bands. Scientists believe these bands to be layers of high and low pressure. As a result, storms often develop on the boundaries between two adjacent bands. The vertical dimension (i.e., thickness) of Jupiter’s atmosphere is more difficult to define than those of the terrestrial planets. For example, whereas the lower boundary for the atmosphere on Earth is its solid planetary surface, there is no such equivalent on Jupiter. Essentially, Jupiter’s atmosphere transitions from a gaseous outer zone into the planet’s liquid layer. However, for practical purposes scientists have designated the depth at which the atmospheric pressure equals ten times the pressure at sea level on Earth as Jupiter’s “surface”. The composition of Jupiter’s atmosphere is very interesting. At roughly 90% hydrogen and 10% helium, Jupiter’s composition is nearly the same as the Sun’s. The only difference between the two is that the Sun is much more massive than Jupiter. This composition supports the theory that Jupiter could have been a star.
ORBIT & ROTATION
With a mean orbital distance of 7.78 x 108 km, Jupiter is, on average, a little more than five times the distance from the Earth to the Sun. This means that it takes about 43 minutes for sunlight to reach Jupiter. Jupiter’s year is about 4,333 Earth days in length— that’s about 12 times the length of one Earth year! Jupiter’s axial tilt of 3.17° is extremely small, second lowest in the Solar System behind Mercury. What this means is Jupiter doesn’t experience seasons at all.
Two things stand out about Jupiter’s rotation. The first is its speed. At just under 10 hours, Jupiter has the shortest rotational period in the Solar System. (Saturn is a close second at 10.7 hours.) This quick rotational speed causes the planet to bulge near its equator, making it less spherical than most of the other planets. The second stand-out characteristic of Jupiter’s rotation is that different parts rotate at different speeds. This is due to Jupiter’s not being a solid body. For example, the polar atmosphere rotates about 5 minutes more slowly than that found at the equator.
Now let’s sum up the conditions on Jupiter that preclude the existence of life.
The planet is a gas giant composed mainly of hydrogen and helium. There is virtually no water to support known life forms. The planet does not have a solid surface for life to develop anywhere except as a floating microscopic organism. Free floating organisms could only exist at the very tops of the clouds due to atmospheric pressure that is progressively more intense than anything seen on Earth. While the cloud tops could harbour life that is resistant to solar radiation, the atmosphere is in constant chaos. Convection forces the lower atmosphere upwards and colder areas of the atmosphere are constantly being sucked closer to the core. The churning would eventually expose any organisms to the extreme pressures nearer the core, thus killing any that may develop. Should an organism find a way to resist atmospheric pressure that reaches 1,000 times what it is here on Earth, there are the temperatures close to the planet’s core. Gravitational compression has heated areas near the core to over 10,000 degrees Celsius. It is so hot in some areas that hydrogen is in a liquid metallic state.
Jupiter is so gravitationally strong that if you stood on its surface, you would be pulled to its core with immense force squashing you into pulp. The force of the gravitational pull would draw you inexorably toward the core where you would be cooked. Or the winds would lift you higher and higher where you would freeze or be killed by radiation from space.
The question ”is there life on Jupiter?” seems pretty well decided. Jupiter is completely inhospitable to life as we understand it, so there is no way that life could exist on the gas giant.
Next week we look at Saturn. I will return you to Earth after we have investigated Uranus and Neptune. We might as well check them all out.