Saturn is at its closest to the Earth this month, at a distance of around 1,300 million kilometres. Even at its closest approach to the Earth, however, it is not possible to distinguish anything more than a star-like point of light with the naked eye and a telescope is required to see its magnificent ring system.

It appears after sunset in the east appearing highest in the sky at around midnight in the constellation Libra. The picture featured on this page was shot on April 20 by British amateur astronomer Damian Peach from Mt. Olympus, Cyprus (1,950m altitude) under excellent observing conditions, away from the turbulent atmosphere and light pollution of the cities down at sea level.

An interesting feature on Saturn is the hexagon-shaped cloud formation shown at the bottom of the photo. Nobody is sure why clouds would form a hexagon shape with straight edges, however, this feature was discovered first from images shot by the Voyager spacecraft in the 1980s and has been observed ever since over 20 years later. Four ‘Earths’ could fit inside the hexagon.

High resolution photographs from these space missions have shown how the rings of Saturn are composed of hundreds of thousands of smaller rings. The rings cannot be solid, because they lie inside the so-called Roche limit. It is thought that they represent either a satellite torn apart by tidal forces, or more probably material that was never allowed to condense into moons because of the tidal forces. The rings are composed of particles that are mostly ice crystals, with sizes as large as centimetres or metres.

Events during this month

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Alexei Pace is president of the Astronomical Society of Malta.