I AM enough of an artist to draw freely upon my imagination. Imagination is more important than knowledge. Knowledge is limited, imagination encircles the world. — Albert Einstein

SATURN is the sixth planet out from the Sun. It is huge, and absolutely massive — no two opinions about that. But, its beautiful appearance and the very elegant ring system lend to it the credence of being billed as the most photogenic of all planets.

I will go a step further: together with the brightest of all stars, Sirius, which comes in sharp and scintillating, shimmering colours during winter nights, planet Saturn is by far the most invitingly beautiful (if that expression is permitted in English language!) of all celestial characters.

The stunningly beautiful planet is named after the Roman god of harvest and, like every other planet, has a symbol of its own: a sickle, an appropriate implement for harvesting. Whenever in our skies, Saturn was supposed to bring a good harvest, and it apparently did. Hence the social and religious reverence accorded to this object d’ art of nature.

The questions that seize our minds at this point in time, as we gaze on the remarkable planet are: what gasses planet Saturn consists of and what materials form its core, mantle and crust? And, what does its ring system comprise of, and, where lies the complexity of the system? Besides, how come the rings are unique as against the main body of the planet? What is the fate of the ring system?

The questions will keep us occupied till we have found the answers that fulfil our curiosity.

First of all, as you know already, planet Saturn came into being — that is, it was formed — at the same time as did the other eight planets and about 100 moons of the Solar System from the very same nebula, about five billion years ago. Needless to say at this point, that all of the moons are not really moons, any which way you try to define them; not all of them. Many are not spherical in shape so it can be safely assumed that these few are captured asteroids, or, in a case or two, former comets that came too close and were “arrested” by the great planet. We have dwelt on this issue before and will do so again in future.

Back to Saturn. For a century and a half, Saturn’s ring system has held a folklore status. In fact, together with Halley’s Comet, presumed canals of Mars and the Great Red Spot of Jupiter, the rings of Saturn have been held in awe by scientists and common folks alike. Visible from the Earth with an ordinary telescope the sight of rings is highly enchanting besides being unquestionably attractive.

Saturn is remarkable in many ways, apart from its lovely ring system. Those few who bend over backwards to insist that Jupiter is a brown dwarf and not a planet, they regard Saturn as the largest planet as a consequence. Whatever, it is second only to Jupiter in size and mass. Its mass is 95 times that of the Earth (Jupiter is 318 times more massive than the Earth). The giant (Saturn) is so large that if its matter is spread out diffusely (rather tenuously, like clouds in the skies of Karachi) it can take in our planet some 750 times over!

Its density is the lowest among all planets: it is so low that if we could find an ocean large enough to put it in, Saturn would float in it! Its low density also suggests that it is not a solid body but mainly consists of gasses, principally the lightest of all elements, namely hydrogen and helium.

Saturn spins on its axis once in 10 hours and 40 minutes. Therefore, it bulges on its equator far more than any other planet, making the equatorial diameter by about 13 per cent longer than the polar diameter. For one full revolution around the master star, the Sun, Saturn requires a sedate 29.5 years.

In form and substance it is not very different from its elder sibling, Jupiter. In the middle it has a core made of liquid rocks several times heavier than Earth, by at least 12 times. Around the core is a layer of liquid hydrogen under such high pressure that it conducts electricity like metals do on Earth. Then comes a thick layer of liquid hydrogen and helium, right on top of which is a thin veneer of atmosphere.

Next comes a puzzle, with which you are already familiar: Saturn has been found to be a few degrees warmer than it should have been. It is admitted that a portion of the emitting heat is borrowed from the distant Sun and then reflected back into space. But it is also generating its own heat at the centre. With Jupiter it is well understood for the truly massive size which is very slowly contracting but Saturn being considerably smaller and no shrinking taking place, any shrinking must have stopped billions of years ago. Then why?

This kept scientists ruminating for generations — until they found the clue. As you know that atoms of helium are slightly heavier than those of hydrogen. As such they are forced to filter down, or drizzle down towards the centre, through continuous layers of hydrogen, thus causing the planetary atmosphere to heat up a little with friction. This was a paradox refusing to surrender, or be found out. Until the time scientists found the answer. It was proved that the upper layers (top) of planet Saturn are very low on the supply of helium, with only hydrogen in abundance. The rest of helium has “dripped” down towards the centre of the planet, in the process creating (or generating) heat. The American satellites Pioneer and Voyagers helped solve the thus far elusive riddle.

Now you know how the secrets of nature can never lay hidden for long. Sooner or later they are discovered and found out. It is much like your mummy hiding away the jar of sweet cookies from you! But for how long!

A discussion on the moon of the great planet is long pending. Of the at least 21 moons of Saturn many, in fact most, are unique in one way or the other. There are the big ones, there are the small ones, the moons come in all colours and hues. And individual characteristics too. We will take a detailed look upon them soon enough. As also the belief that both Jupiter and Saturn are in fact twins of some sort.

For the secrets of Saturn’s ring system and a plethora of moons dancing around this wonderful planet let us meet in the next issue!

The writer is a professional astronomer and a former head of PIA Planetarium. He can be reached at astronomerpreone@hotmail.com