Look Up! Saturn Opposes the Sun
Saturn's illuminated majestic rings and the gas giant's shadow are captured during this 2007 Cassini mission photograph.NASA/JPL-Caltech/SSI
Of all the planets in the Solar System, there are none as stunning nor intriguing as Saturn. It has been known for thousands of years, though only with the invention of the telescope was its true nature revealed.
It's an alien world that is easy to spot with the unaided eye and even with a basic telescope, Saturn's true beauty is there to be enjoyed. April is a great month to take a look at the planet as it lies at opposition on April 12 — meaning it is opposite to the sun in the sky so is visible all night, rising as the sun sets and setting as the sun rises.
It only takes a magnification of around 20 to 25 times for the rings to become visible, so even a small bird-spotting telescope will resolve them, but a larger telescope is needed to see the gaps in the rings or the belts around the planet.
My first ever view through a telescope was of the ringed planet and seeing it for real ignited a fire in me that burns strong even today, more than 20 years on. But like all things in astronomy, and science in general, Saturn remains a mystery in many ways and there are many things about the planet that we still don't fully understand.
For starters, it's not fully understood why Saturn is the only planet with an incredible system of rings, unrivalled in their splendour by the faint rings of Jupiter, Uranus and Neptune. We do know that the rings are made from countless tiny pieces of ice and dust. We also know that the rings are sculptured by tiny moons in orbit around the planet, gravitational interactions forming spaces between the rings. But why Saturn has such an extensive system is unknown.
Current theories suggest they are either the result of a moon — which was destroyed by a collision or by the tidal forces of the gas giant — or leftover material from the planet's formation.
When the rings were studied closely during the Voyager 2 spacecraft flyby in 1981, strange dark features known as "spokes" were spotted in the so called 'B' ring. Strangely, the spokes seemed to retain their shape, which was inconsistent with the idea that they should change in appearance. The actual nature and cause of the spokes is unknown but based on their visibility it seems they are made from microscopic dust particles suspended above the rings by electrostatic effects. The origins of the dust particles is the real mystery — perhaps they originate from micrometeoroid impacts on the rings?
The planet itself has mysteries all of its own. While the upper layers of the Saturnian atmosphere is quite bland in comparison to the other giant planets, occasional planet-wide storms erupt every thirty years or so. This seems to be linked in some way to seasonal variations on the planet that has an orbital period around the sun of just under thirty years. However, the storm in Dec. 2010 erupted about ten years too early!
The higher latitudes around the north pole are also exhibiting strange atmospheric phenomena as first seen by Voyager in the 1980's. A strange hexagonal cloud seems to have taken residence over the north pole, large enough to swallow four Earths. These shapes have been simulated on Earth in enclosed containers but quite why it's happening in the atmosphere of a massive planet is still unknown.
It may be many years before we finally solve these and other mysteries of the ringed planet. But until then, the sixth planet from the sun will retain a special place in my heart and I hope its beauty and mysteries will continue to inspire and intrigue people for many more years to come. So tonight, remember to look up.