Saturn isn't a slouch either, however Jupiter may be the stormiest spot in
the Solar System. According to a recent research, the ringed behemoth also
experiences recurrent megastorms that may endure for a century and leave
long-lasting atmospheric scars.
A team of astronomers led by Cheng Li of the University of Michigan
examined radio waves released by Saturn and discovered long-lasting signs of
huge storms, including equatorial storms that occurred hundreds of years
ago.
This is an intriguing look into Saturn's dynamics, and it can provide light
on the mysterious megastorms that rage every few decades.
Li argues
that comprehending the principles underlying the Solar System's biggest
storms "puts the theory of hurricanes into a broader cosmic context,
challenging our current knowledge and pushing the limits of terrestrial
meteorology."
With the exception of its amazing ring system, Saturn seems somewhat dull
and brown at pure optical wavelengths.
But in radio light, the entire planet appears to be surrounded by a series
of sharply contrasted atmospheric bands. This eye-catching view enables
scientists to track the ammonia in Saturn's atmosphere because ammonia
absorbs radio waves.
Li and his coworkers made thorough radio observations of Saturn with the
Very Large Array
of the National Radio Astronomy Observatory in order to investigate the
distribution of ammonia in the atmosphere.
Only a little amount of water, methane, and ammonia are present in
Saturn's atmosphere, which is mostly composed of hydrogen and helium. However, the ammonia
predominates in the top layer of cloud. Scientists can examine what is
underneath that higher layer using radio measurements.
The researchers discovered something intriguing at this location.
We explore the large planets' invisible cloud layers at radio frequencies.
Imke de Pater, an astronomer at the University of California, Berkeley, states that
observations below these cloud layers are necessary to constrain the
planet's true atmospheric composition, a crucial component for planet
formation models. This is because chemical reactions and dynamics will
change the composition of a planet's atmosphere.
"Radio observations help characterize dynamical, physical, and chemical
processes, including heat transport, cloud formation, and convection in the
atmospheres of giant planets on both global and local scales."
Their radio pictures' brighter bands reveal substantially lower ammonia
concentrations in those bands. The scientists discovered ammonia in Saturn's
top cloud layer as they had predicted, but they also discovered abnormally
high amounts of the gas between 100 and 200 kilometers (62 and 124 miles)
deeper in the atmosphere. Between the two, the mid-altitude zone is largely
ammonia-free.
According to the team's calculations, the megastorms that occur on Saturn
every 28 to 30 years (or once per Saturn year) precipitate ammonia farther
into the atmosphere, where it evaporatively transports back to the cloud
tops. Since ancient megastorms can last for hundreds of years after they
have passed, deep ammonia concentrations can serve as recorders of such
events.
With each of the six megastorms that have been documented on Saturn since
1876, the researchers were able to link abnormalities they had discovered.
Additionally, scientists discovered an anomaly that they think points to an
even earlier megastorm.
We frequently draw parallels between the happenings on Saturn and Jupiter
since they are both gas giants. The team's findings also demonstrate that
the two are more dissimilar than we once believed. Jupiter's alternating
bands of dark and light clouds are linked to temperature anomalies. The
storms rule the day on Saturn. This is a hint that can help us understand
the many paths gas giant exoplanets can take in their evolution.
The following megastorm is anticipated to occur in 10 or 20 years. To see
what fresh things it can teach us will be exciting.
The research has been published in
Science Advances.
