These results support the possibility that Saturn’s rings formed billions of years ago, perhaps at the time when giant impacts excavated the great basins on the Moon. The findings also suggest that giant exoplanets may also commonly have rings.
Dr Larry Esposito, Principal Investigator of Cassini’s UVIS instrument, will be presenting the results at the European Planetary Science Congress in Münster on Tuesday 23rd September.
“Both Cassini observations and theoretical calculations can allow the rings of Saturn to be billions of years old. This means we humans are not just lucky to see rings around Saturn. This would lead us to expect massive rings also to surround giant planets circling other stars,” said Dr Esposito.
Esposito’s colleagues at the University of Colorado, Glen Stewart and Stuart Robbins, have computed the gravitational attraction and collisions between more than 100,000 particles, representing a sample of those in Saturn’s rings. They followed the orbit and history of each individual particle, and calculate the amount of starlight that would pass through the ring. These results have been compared to Cassini observations of starlight blocked by the rings, which has traditionally been used to estimate the total amount of material in the ring system. Esposito used this method in 1983 to estimate that rings of Saturn contain as much material as Saturn’s small moon Mimas, which is about 250 miles across. The new simulations show Saturn’s ring particles aggregate into clumps, which would lead to the previous estimate being low by a factor of 3 or more.
Calculations by Esposito and his student Joshua Elliott show that meteorites slowly grind and shatter the particles in the ring. Gradually, a layer of dust and fragments builds up and covers each particle. This layer includes both ice (from the particle) and meteoritic dust. As time passes, the ring system is more polluted and darkened by meteoritic dust.
Because the rings appear so clean and bright, it was argued that the rings of Saturn were much younger than Saturn, which is some 4.5 billion years old. It was calculated from Voyager measurements that the rings are only about 100 million years old, approximately as ancient as when dinosaurs inhabited the Earth. The new calculations show that if the rings are more massive, they appear less polluted, and thus could be proportionately older. Recycling of ring material extends their lifetime and reduces the expected darkening.
One problem with this proposal for more massive and ancient rings is that the Pioneer 11 space mission to Saturn in 1979 measured the ring mass indirectly by observing charged particles created by cosmic rays bombarding the rings.
“Those mass estimates were similar to the ones from Voyager star occultations, apparently confirming the previous low mass value. However, we now recognize that the charged particles are double-valued. That means they could arise from either a small or large mass. We now see that the larger mass value could be consistent with the underestimates due to ring clumpiness,” said Dr Esposito.
Anita Heward | alfa
Enhancing the quantum sensing capabilities of diamond
23.11.2017 | The Hebrew University of Jerusalem
Quantum optics allows us to abandon expensive lasers in spectroscopy
22.11.2017 | Lomonosov Moscow State University
Heat from the friction of rocks caused by tidal forces could be the “engine” for the hydrothermal activity on Saturn's moon Enceladus. This presupposes that...
The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.
Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
23.11.2017 | Information Technology
23.11.2017 | Physics and Astronomy
23.11.2017 | Life Sciences