A Lancaster University PhD student has measured the optical depth of The optical depth is connected to the transparency of an object, and it shows how far light can travel through that object before it gets absorbed or scattered.
Cassini Mission and Research Collaboration
The research, led by Lancaster University in collaboration with the Swedish Institute of Space Physics, was recently published in the Monthly Notices of the Royal Astronomical Society.
The
Video of the Cassini spacecraft moving through the plane of Saturn’s ring system, created by George Xystouris using NASA Eyes. Credit: NASA/
Methodology and Findings
Lancaster University PhD student George Xystouris, under the supervision of Dr. Chris Arridge, analyzed historic data from the Langmuir Probe onboard Cassini, an instrument that was measuring the cold
“Focusing on the data variations we realized that they were connected with how much sunlight each ring would allow to pass. Eventually, using the properties of the material that the Langmuir Probe was made of, and how bright the Sun was in Saturn’s neighborhood, we managed to calculate the change in the photoelectrons number for each ring, and calculate the optical depth of Saturn’s rings.
“This was a novel and exciting result! We used an instrument that is mainly used for plasma measurements to measure a planetary feature, which is a unique use of the Langmuir Probe, and our results agreed with studies that used high-resolution imagers to measure the transparency of the rings.”
Future Visibility of Saturn’s Rings
Τhe main rings, which extend up to 140,000 km (90,000 miles) from the planet, but have a maximum thickness of only 1 km (0.6 miles), are to disappear from view from Earth by 2025. In that year the rings will be tilted edge-on to Earth, making it almost impossible to view them. They will tilt back towards Earth during the next phase of Saturn’s 29-year orbit and will continue to become more visible and brighter until 2032.
Professor Mike Edmunds, the President of the Royal Astronomical Society, added: “It is always good to see a postgraduate student involved in using space probe instrumentation in an unusual and inventive way. Innovation of this kind is just what is needed in astronomical research – and an approach which many former students who are in a variety of careers are applying to help address the world’s problems.”
Reference: “Estimating the optical depth of Saturn’s main rings using the Cassini Langmuir Probe” by Georgios Xystouris, Christopher S Arridge, Michiko M Morooka and Jan-Erik Wahlund, 18 September 2023, Monthly Notices of the Royal Astronomical Society.
DOI: 10.1093/mnras/stad2793