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World: Space Probe Finds New Ring, New Moon Around Saturn

  • Jan Jun

The "Cassini-Huygens" Saturn probe is continuing to bring new information about the sixth planet in the solar system. The latest discovery involves a new ring around the planet and new moon -- Saturn's 34th known satellite. The discoveries indicate the planet's moons may influence the shape of the rings.

London, 13 September 2004 (RFE/RL) -- The discovery of the new ring and moon was credited to British astronomer Carl Murray of Queens College, at the University of London. But Professor Murray tells RFE/RL he played only a small part in the discovery.

"I should say the discovery belongs to the [entire] Cassini imaging team. I am a member of that team. I was just lucky enough to be the first person to see it, but the credit belongs to the entire team," Murray said.

Murray says the imaging team discovered the new ring and moon by studying hundreds of images from the spacecraft -- now in orbit around Saturn. Team members then compared the current images with images collected by another space probe -- the U.S. "Voyager" probe -- that flew past Saturn some 20 years ago.
"It's like the crime scene. You see the evidence before you, and then you're trying to deduce who was at the scene of the crime. Which moons were there, are the moons, the suspects if you like, that you haven't seen yet, you haven't interviewed yet."


"The new ring that was discovered was in an image taken on 1 July. Just after the spacecraft had its main engine burn, and had looked down at the rings, crossed the rings plane and looked back up at the rings again. The viewing geometry that we got showed us this ring," Murray said.

A total of four planets in the solar system are known to have rings -- the others are Jupiter, Neptune, and Uranus -- though Saturn's remain by far the most spectacular.

Saturn's rings were first viewed by Italian astronomer Galileo Galilei in 1610, but only identified as rings later by Dutch astronomer Christian Huygens. Galileo's compatriot, Giovanni Cassini, discovered Saturn's largest moon, Titan.

The space probe was named "Cassini-Huygens" to recognize the contributions of these early astronomers.

The discovery of the new moon, some three to five kilometers wide, was part of the study of the ring structure. Scientists have labelled Saturn's rings according to the letters of the alphabet. Murray focused on the outermost "F" ring.

"The images that this new moon appeared in were taken on 21 June. In the whole sequence of images that was designed by the imaging team leader Carolyn Porco to look for small, undetected moons. It was in that sequence that I actually was the first person to spot this moon pass around the outer F-ring," Murray said.

Murray says the work of the imaging team can be compared to that of police detectives at a crime scene.

"It's like the crime scene. You see the evidence before you, and then you're trying to deduce who was at the scene of the crime. Which moons were there, are the moons, the suspects if you like, that you haven't seen yet, you haven't interviewed yet. You have to go through this process to try to find all the likely suspects, and then figure out who was actually responsible," Murray said.

Another British researcher, professor Stan Cawley of the University of Leicester -- whose team has discovered magnetic storms on Saturn -- thinks the discovery of the new moon confirms that the moons influence the shape of the rings.

"These new images resolve that problem, because it's clear that there is at least one new moon close to this ring, which is causing all the structure in it that we see," Cawley said.

Murray expects yet more new discoveries to take place.

"We are taking images virtually all the time. At the moment we are really quite far out, so most of the images that I would be interested in will be taken again probably next month or the month after, as we get really close into the system. But we are in orbit around Saturn for four years, and we have over 70 orbits of the planet. So, there will be lots more opportunities to look for small moons and perhaps new rings to see how they all interact with each other," Murray said.

So, it seems, Saturn might have more surprises in store.
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