Giant Ring around Saturn

Today's newspapers carried exciting find of a mega ring around Saturn. Read on:

Scientists have discovered a giant ring around Saturn, the biggest yet discovered in the solar system.

The “supersized ring”, as it being called by the scientists from the University of Virginia who discovered it, is so big it would span the width of two full moons worth of sky if you could see it from Saturn.

Saturn’s rings were first discovered almost exactly 400 years ago by Galileo Galilei and are visible with even the smallest telescopes, but this ring is only visible in the infra-red light and was first spotted by Nasa’s Spitzer Space Telescope.

It is about 10 times the diameter of Saturn and orbits at a distance of eight million kilometres from the planet.

It covers a volume of space which would contain a billion Earths though it is made of an extremely tenuous film of dust from Phoebe, one of Saturn’s outer moons.

Irish-born scientist Prof Carl Murray said the discovery did not come as a surprise as it had been speculated about in a little known scientific paper delivered 30 years ago.

Prof Murray, who is one of the chief scientists on the Cassini spacecraft mission which has been photographing Saturn and its ring systems for years, said it solved a mystery as to why one of Saturn’s moons, Iapetus, is heavily marked on one side and completely smooth on another.

“When I heard about it, I just nodded and said ‘yes that’s almost what we suspected’,” he said.

Prof Murray will give a lecture at the Dundalk Institute of Technology tonight at 8pm and at Trinity College tomorrow hosted by Astronomy Ireland, where he will discuss the new discovery.

“Phoebe is the source of the ring material. We had a 300-year problem observed by the original (Giovanni) Cassini who discovered Iapetus and who saw that it appeared to have a dark and a bright hemisphere.”

Like our moon, Iapetus is tidally locked with the planet so the side facing Phoebe would be one that would be impacted from debris coming from that moon.

“We had some indication about this from the Voyager spacecraft (which photographed Saturn and its moons in the early 1980s), but we finally saw with the Cassini images that Iapetus had a coating.

“It was theorised that if Phoebe was impacted and ejecta came off it would spiral in towards Saturn and the first moon it would come to is Iapetus. It all seems to make sense,” the professor explained.

“We suspected there must be a ring. It was like a smoking gun and we now have the evidence.”

Meanwhile, scientists will tomorrow target our own Moon to find out if there are large quantities of water hidden in craters which never see sunlight.

At exactly 12.31pm Irish time, the Lunar Crater Observation and Sensing Satellite (LCross) will send a rocket into the lunar surface near the Moon’s South Pole.

The impact of the explosion will throw up 350 tonnes of lunar dust, which will be analysed by LCross before it too crashes into the surface.

Coincidentally, last month the Indian satellite Chandrayaan 1 discovered traces of water across the Moon and particularly in the polar areas, a discovery which would have seemed wholly improbable a couple of decades ago.

If the scientific hunch is correct and there are billions of gallons of water frozen near the Lunar poles, it could prove to be critical in establishing a permanent manned base on the Moon.
- Ronan McGreevy in The Irish Times