ABOUT    JUPITER

Fast   Facts

5th planet from the Sun. Has 63 moons, 4 of them planet-like.

Largest in the Solar System, 2.5x larger than all the other planets combined.

Apart from the Sun, accounts for over two thirds the mass of the Solar System, asteroids, comets and moons  included.

Diameter      141,968 km    (11.2x Earth; second only to the Sun- 1/10 of it).

Volume        1.425x1015 km3  (1316x Earth).  You can stuff 1300 Earths into Jupiter.

Mass            1.9x1027 kg. (317.8 xEarth).

Orbit            11.9 years  (12x Earth).

Day  or rotation  9 hrs.  50 min. (Earth is 24 hrs- 2.5 x longer).

Distance from sun  7,737, 000,000 km (5.2x earth).

Escape velocity 214,300km/hr. (59.5km/sec; Earth’s is 11.2km/sec)

4th brightest object in the nightsky  (after the Sun, the Moon and Venus).

IN   JUPITER

Resembles  a star more than a planet in composition. It’s called a gas giant with an atmosphere iof about 90% Hydrogen, 10 % Helium and small amounts of other gases like Ammonia and Sulphur and WaterVapour.  Compounds of Sulphur are mainly responsible for the colour we see on Jupiter.

About 150 km. beneath Jupiter’s atmosphere is a “crust” of Hydrogen gas.  Beneath this is a mantle of  metallic and liquid Hydrogen and way down a small, rocky core of  about 10-15 Earth masses  . The rapid                        rotation of the planet  bulges  the diameter at the equator 7% greater than at the poles.

Jupiter has a magnetic field stronger than that of Earth  (about 20,000x more)  and it’s magnetosphere extends between 3-7 million  km. in space (close to the orbit of Saturn).

Jupiter radiates more energy into space than it receives from the Sun. It’s interior is hot: probably over 20,000o C at the core ( Earth is 5, 500oC; the Sun is 15 million degrees C), the heat being produced by slow gravitational compression  of the planet. It does not have the size

or temperature to initiate nuclear fusion like the Sun. It would require a size 80X more than  and a temperature of several million degrees C.

ON   JUPITER

What we see on Jupiter is weather.  Weather on Earth is influenced by the sun.  On Jupiter, it is influenced by the vast gaseous envelope of the planet and by the internal heat generated deep within.  Jupiter’s tilt is just 3o (Earth’s is 23o ).  A thick atmosphere of Hydrogen and Helium forms  multi-coloured, latitudinal bands of clouds, atmospheric clouds and storms . These are all driven by thunderstorms, and illustrate the planet’s dynamic weather system. The vivid colours of Jupiter’s clouds are probably caused by reactions of the trace elements in the atmosphere. The colours indicate the height of the clouds- blue being the lowest. Then the browns, the whites and red being the highest. The light coloured bands are called zones, the dark coloured ones, belts.

Jupiter’s most famous feature is a swirling mass of clouds that is higher and cooler than the surrounding areas.It’s called the Great Red Spot, and is caused by tremendous winds that develop above the rapidly spinning planet.  It is likened to a supermassive hurricane with winds blowing  around the disturbance at about 400km/hr. It rotates counter clockwise every 6 -12 days. In comparison, Earth’s hurricanes generate wind speeds of 280 km/hr maximum. The Great Red Spot is about twice the size of Earth and is in the southern hemisphere of the planet. It has been raging for at least 300 years  (compare it to Earth’s storms and hurricanes which die after 4 or 5 days).  It is one of several  storms on Jupiter as the development of a second and third red spots have been observed, though not as massive as the first. The red colour is probably due to Sulphur compounds.

Auroral  emissions have been observed in the polar regions  and cloud-top lightening bolts, similar to those in Earth’s high atmosphere, have also been noticed. These are caused  partly by bombardment from the sun, and by volcanic activity on Io, the innermost Gallilean moon.

In  1994, the Earth looked on as fragments of the Shoemaker-Levy 9 comet slammed into Jupiter just as forecasted.  About a year before, the planet’s immense gravity had captured the comet and ripped it into many pieces. The orbits of the pieces were predicted and the actual impacts were witnessed by powerful telescopes.  Between July 16-22  (do the dates mean anything?)  21 pieces in all slammed into the southern part of the planet at speeds of 60 km/sec. Bright impact clouds more than 13,700 km in diameter  were caused by  several  impacts. Fireballs of rising material 3,000 m high were measured as the comet fragments plunged into the layers of gas.