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Astronomy - Planet Jupiter
Mass: 1.90 X 1027 kg (317.9 Earths)
Radius (equatorial): 71 492 km
Mean density: 1.33 g cm3
Distance from Sun: 778 330 000 km
Rotational period: 0.4135 days
Orbital Period: 4332.71 days
Escape velocity: 59.56 km s-1
Apparent magnitude: -2.70
Surface temperature: -121°C (cloud)
Atmospheric composition: hydrogen (90%), helium
(10%)
Number of statellite: 16 (Europa, Ganymede, Callisto, Io etc.)
Characteristics
Jupiter is the largest planet and is the fourth brightest object in the sky, after the
Sun, the Moon and Venus. Its volume can fit in more than one thousand Earths
and contains more matter than all of the other planets combined. Jupiter's
magnetosphere, measured by the Cassini spacecrsft is found to extend far into
space, with a distance equivalent to 30 times the radius of the planet. If its
magnetosphere is visible from Earth, it would appear five times as large as the full
moon. Unlike Saturn, Jupiter has also a ring system but is much thinner and very
faint. It was only discovered whenVoyager 1 approached the planet in 1979.
One can only speculate the structure of the planet. Its atmosphere is very thick
and deep. The interior pressure may reach 100 millions times the pressure on
Earth's surface. Just like the Sun, it is composed of mainly hydrogen and helium.
Jupiter's weather is highly dynamic. Strips of latitudinal bands and turbulance
clouds are clearly visible even with a small telescope. The charactristic red spot
(The Giant Red Spot) is in fact a complex strom, moving in a counter-clockwise
direction, has been raging for hundreds of years. The first direct measurement of
its upper atmosphere was first carried out by the Galileo Probe in July 1995. The
probe managed to penetrate about 200 km before it was crushed by the
atmosphere.
Jupiter has 16 known moons. The four largest moons (named in order of
increasing size: Europa, Io, Callisto and Ganymede) were discovered by Galileo
Galilei in 1610 and are subsequently known as the Galilean satellites. Apart from
the 16 named moons, recently 23 more have been discovered but not yet been
named.
4. Jupiter’s big. No, really really big. And massive too.
Jupiter has the most mass of any planet in the Solar System. You may be wondering exactly how massive
this planet is. Not only is Jupiter’s mass 318 times the mass of the Earth, but it is also two and a half times
the mass of all the planets in the entire Solar System. Even though the planet is massive, it has a density
lower than Earth’s. This causes Jupiter to have a gravity approximately two and a half times greater than
Earth’s gravity.
5. And yet, Jupiter is the fastest rotating planet
Despite Jupiter’s large mass, it is the fastest planet to complete a full axial rotation. It takes just under ten
hours for the planet to do a full rotation. As a result of its extreme speed, Jupiter has actually flattened at
both ends and expanded in the middle like a ball that is being compressed between someone’s hands.