Saturn is well known for its rings, which can be seen with a common
telescope. Scientists have now found a previously unseen interplay between
the planet and its signature rings by using data gathered over a 40-year
period to show that the planet's famous rings may not be as tranquil as they
appear.
The vast ring system of Saturn is heating its higher atmosphere, an
occurrence that has never been observed before in the solar system,
according to a compilation of past studies of the planet.
This result was reached by combining data from four NASA planetary probes
that observed ultraviolet (UV) radiation. This included data from the
Cassini mission, which landed at Saturn in 2004, and gathered UV data over a
number of years, as well as the Voyager 1 and 2 spacecraft that passed by
Saturn in the 1980s, detecting UV excess that was thought to be noise at the
time. The Hubble Space Telescope and the International Ultraviolet Explorer,
both of which were deployed in 1978, provided additional data.
Scientists already knew that particles in Saturn's rings were steadily
falling in towards the planet based on data from the Cassini spacecraft.
Unexpected was how the planet's atomic hydrogen levels were impacted by the
bands' breakup. Atomic hydrogen is very volatile because it only exists as
single atoms, not compounds.
Although the gradual disintegration of the rings is well known, its impact
on the planet's atomic hydrogen came as a surprise, according to research
main author Lofti Ben-Jaffel. "We were already aware of the impact of the
rings thanks to the Cassini spacecraft. But we were unaware of the atomic
hydrogen concentration.
The finding relied heavily on the linking of the archived data using
high-resolution readings from the Imaging Spectrograph (STIS) on the Hubble
Space Telescope. The exact STIS measurements were used to calibrate the
historical data that the Voyager and Cassini spacecraft had already
collected. An overabundance of UV light was visible in the resulting picture
as a spectral line of hot hydrogen in Saturn's atmosphere, which denotes
atmospheric heating.
The scientists believed that a constant shower of icy particles pulled in
by Saturn's gravitational pull from its rings and dropping onto the planet
was the most plausible account for the planet's atmospheric heating.
According to Ben-Jaffel, "everything is driven by ring particles cascading
into the atmosphere at specific latitudes." They alter the makeup of the
higher atmosphere.
It is anticipated that the unexpected interaction between Saturn's rings
and the planet will help scientists establish whether exoplanets circling
other stars have ring systems similar to Saturn's. The UV radiation spectra
of a planet could be used to detect them even though they would be too far
away to see them.
According to Ben-Jaffel, "this ring characterization effect on a planet's
upper atmosphere is just getting started." "We ultimately want to have a
worldwide strategy that would produce an accurate signature of the
atmospheres on other planets. Investigating its applicability to worlds
orbiting other stars is one of the objectives of this research.
The study was published in the
Planetary Science Journal.
