Saturn – the most magnificent planet in the solar system

Posted in Science, Space, Travel on Friday, 23 March 2012

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This edited article about space originally appeared in Look and Learn issue number 674 published on 14 December 1974.

Saturn, picture, image, illustration

Space probe passing Saturn by Wilf Hardy

Imagine looking out of your bedroom window on a clear night and seeing ten moons shining brightly in the sky. It would be a wonderful sight. But it is one you are never likely to see, for you would have to live on Saturn to witness it. And to do that is a highly improbable enterprise because Saturn has no solid surface.

However, man may one day set up an outpost on one of Saturn’s moons – Titan for example – and use that to find out more about Saturn and its satellites.

But first, let us get Saturn into perspective. It is the most magnificent planet in the solar system. But as its nearest distance from us is 1,028 million miles, its glory can only be seen through a powerful telescope. Saturn is 67,000 miles in diameter and its average distance from the Sun is 887 million miles.

The planet is surrounded by three rings. The outer one is 171,000 miles in diameter and 10,000 miles from edge to edge. The inner one is 122,000 miles in diameter and 11,500 miles from edge to edge. These rings are composed of ice-coated particles and there are times when the rings and the gaps between them are visible from Earth.

In fact, Saturn’s rings are unique. Nothing quite like them has been discovered in astronomy. Viewed through a telescope, they are a beautiful, unforgettable sight. Both astronomers and mathematicians became very interested in them in the 19th century. It was Clark Maxwell, a Scottish physicist (1831 – 79) who proved mathematically that they were composed of minute particles. This was again confirmed in 1895, when the spectroscope showed that the rings rotated faster on the inside than the outside.

More divisions were found, and astronomers also detected a semi-transparent inner ring now called the Crepe Ring.

However, although such long-distance observations are valuable, we may get more help from future space flights. An American Mariner craft is due to reach Saturn in 1981. And Pioneer II is expected to fly past this planet. It may be possible to direct it to fly inside the rings to find out how dense are the particles and whether Saturn has a magnetic field.

When this happens, we may know almost as much about Saturn as we do about Jupiter, which has been approached by Pioneer 10. This craft just managed to survive the intense radiation belts which surround this, the largest planet in the solar system.

The wealth of new information with which it returned has revealed many new facts and opened new speculations about Jupiter’s environment.

This giant in the sky is 88,700 miles in diameter and, at its nearest to us, is 390 million miles away. It probably consists of a mass of gases, surrounding a comparatively small, solid core. Its cloud blanket is encircled by a series of coloured rings.

There is also on the cloud surface a red spot, 30,000 miles long and 8,000 miles wide.
Like Saturn, Jupiter has several moons, twelve to be exact, and the largest is bigger than our Moon. Most of them are of rock, but one may be made of ice.

Pioneer 10’s observations showed that Jupiter has a powerful magnetic field and to possess protons and high energy electrons in its radiation belts. In fact, the space craft received a radiation dosage a thousand times heavier than that required to kill a man.

Helium was detected in the atmosphere, which is now known to consist of hydrogen, helium, ammonia, methane and several minor constituents.

It was also discovered that there is little difference between the temperature of the sunlit and dark sides.

The strange thing to consider, when thinking of the immense size of Jupiter, is that it weighs more than all the eight other planets put together. If it could be magically shrunk down to the size of a football, our Earth would be about as small as a cherry.

And Jupiter is amazingly different from Earth in other ways. One month (one moon orbit of the Earth) is about 27 days by lunar time. But Jupiter can have twelve different months to choose from, varying from six hours to over two years, because it has twelve moons.

A ‘year’ on Jupiter is a very long time by our standards. A child on Earth could be born and grow up to be ten before Jupiter circled the sun. And yet a ‘day’ on Jupiter is just over nine hours by our time – a Jupiter calendar would have to be divided up into 10,000 ‘days’.

Because Jupiter is so far away from the sun (more than 480 million miles compared with the Earth’s 93 million miles) sunlight is very weak, less than a thirtieth of the brightness of our sunlight. This makes Jupiter extremely cold.

Scattered between the orbits of Mars and Jupiter are thousands of midget worlds which are too small to be called planets or moons and which do not travel in paths like planets or moons. These are called asteroids or planetoids and only three of them have diameters of over 250 miles. These are Ceres, whose diameter has been computed by various scientists as being from 427 to 485 miles, Vesta with its diameter of about 370 miles and Pallas whose diameter is about 280 miles.

Scientists have been extremely interested in these planetoids and one man, Arthur Clarke, suggested a unique use for Icarus. This is a body which approaches to within 17,000,000 miles from the sun’s surface.

He suggested that when Icarus is at its closest to Earth, it might be possible for a space craft from Earth to dock with it and place a radio transmitter either on its surface or buried beneath it.

This would enable scientists to study the Sun, since Icarus passes so close to it. But the problem of heat damage arises, for Icarus must become a red hot ball when it is near to the Sun. The likelihood of scientific apparatus surviving at such a temperature is remote. But if equipment could be designed to resist such great heat, the value of the information it would provide could be immense.

Even more ambitious is the proposal to establish an outpost on Titan, one of Saturn’s satellites, so that this planet could be observed. It just goes to show that, in outer space, exploration has few limits.

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