Saturn’s moon casts shadow on its ring

June 15th, 2009 - 12:47 pm ICT by ANI  

Sydney, June 15 (ANI): The Cassini spacecraft has found long shadows in a ring gap created by the eight-kilometre-wide Saturn moon Dephnis, which orbits in the planet’s outer A ring.

According to a report by ABC News, taking advantage of a very low sun angle relative to the planet’s rings, Cassini scientists found the shadows in the ring gap.

Extrapolating from the results, the team determined the moon was creating a vertical structure about one and a half kilometres in height, or150 times as high as the rings are thick.

The planet’s three main rings are about 10 metres thick.

Scientists had predicted that gravitational forces associated with embedded moons would create vertical structures as they dip above and below the ring plane, but they have never before observed it.

“It’s one thing to get data back that shows you’re right about something, but to get pictures that are this stunning is really wonderful,” said Dr John Weiss, a Cassini researcher with the Space Science Institute in Colorado.

The images were taken over the past several weeks as part of ongoing studies of Saturn’s ring system.

The Cassini spacecraft was about a million kilometres away and nearly directly above the rings for the shoot, which was made possible by a Sun angle that occurs once every 15 years.

In addition to unravelling some of the inner workings of the Saturn system, the studies are expected to help scientists refine measurements of moons embedded in the planet’s rings.

The research also could help scientists understand the physics of protostellar systems and other disk systems, like galaxies.

Scientists will continue looking for structures in Saturn’s rings while the Sun is in favourable alignment throughout the next several months.

They also are trying to find tiny moonlets that may be creating 10 unaccounted for gaps in the planet’s rings.

Cassini arrived at Saturn in 2004 and completed its primary four-year mission last year.

The team won funding for a two-year extension to study the planet during equinox, when the Sun will be directly overhead at noon on the planet’s equator.

The alignment, which occurs every half-Saturn year, or about 15 Earth years, lowers the Sun angle relative to the plane of the rings, causing any out-of-plane structures to cast long shadows across the rings’ surface. (ANI)

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