I have had a few clear nights of late, which is unusual for me living in the UK, the weather is typically not my friend. But one of the nightly delights has been seeing enigmatic Saturn rise in the East as the sky darkens.
Saturn is the sixth planet from the sun and holds a special place in my heart as it was the first thing I ever saw through a telescope when I was ten years old.
The ringed planet is easy to spot just to the east of the bright star Spica in the constellation Virgo. To the naked eye it looks like a modestly bright yellow star, but a telescope reveals a stunning world with mysteries just waiting to be unveiled.
The most iconic features of Saturn is the glorious ring system that can be seen through a telescope with a magnification of around 20x or more. Powerful telescopes will reveal a greater level of detail, but at first glance the rings may actually appear to be solid.
Closer study reveals voids in the rings like the famous "Cassini Division" discovered by Giovanni Cassini in 1675. The division is not completely empty, however, but it is one of many regions of much lower ring particle density whose origin lies with the nature of the rings themselves.
Saturn’s rings, like all planetary ring systems, are made up of countless billions of pieces of ice and rock all in orbit around the planet. The resonances of forces that generate the gaps are varied but many, like the Cassini Division, are caused by gravitational forces from Saturn's moons.
In the case of the Cassini Division, the moon Mimas orbits Saturn once for every two orbits of particles straying into the 4,800 kilometer wide gap. This resonance causes a constant tug on the particles in approximately the same direction, which forces them out of the division. There are other causes for gaps in the rings of Saturn -- for example, some moon's of Saturn orbit within the ring system and their gravitational influence keeps some gaps clear of debris.
The gaps and fine rings surrounding Saturn are generally the result of gravitational effects in one way or another but one other feature less well understood are the strange, almost ghostly "spokes."
As their name suggests, they resemble the spokes of a bike, radiating out across the ring system and were first spotted back in the 1980's. They seem to vary in brightness and size and can last many hours before fading from view. Their origin is still unknown but it is thought they may be the results of microscopic ice particles interacting with ring particles and Saturn's magnetic field as they orbit.
Unlike the spokes in Saturn's rings, the rings themselves are easily observed by amateur astronomers. As the summer progresses and Saturn climbs higher in the sky, do try and take a look at Saturn, it is the object that ignited a fire deep inside me nearly thirty years ago and maybe, just maybe, it will spark something inside you too.