The Importance of Planetary Rings as Astrophysical Laboratories
If you are a stargazing enthusiast, then there is a good chance you have observed the rings of Saturn. But apart from their fascinating structure, these rings hold more value than just as a mere reminder of how beautiful the universe can be. Dr. Phil Sutton explores the purposefulness of planetary rings in his seminar, “The importance of Planetary Rings as Astrophysical Laboratories”, delivered on the 15th of October 2025.
First and foremost, you may not be acquainted with such structures as planetary rings, so what are they?
As Dr. Sutton explains, these rings are an assembly of particles that orbit a planet in a common direction. In this context, the term particle does not refer to actual sub-atomic particles, like electrons or protons, but to a wide range of different-sized objects measuring at around 1 to 30 meters in the inner rings of the planet, and about a millionth of a meter in the outer rings. The gravitational effect of the oblateness of the planet (how “squashed” the planet is) causes the rings to be extremely flat and hold almost perfect circular orbits. The immense volume of particles within the ring creates a collision blockade, bumping any particle in a non-circular orbit back to a circular one, keeping the flatness and circular orbit of the ring stable.
Within the ring system itself, gaps can be observed in between rings. These gaps are often caused by embedded moons within the rings that, due to their enormous size in comparison to the ring particles, “push” any material out of their way by means of a significantly greater gravitational force. If these moons are big enough, then the gaps are clear and sometimes even visible via telescope! But for smaller moons (moonlets), only local disturbance is created, showcasing propeller-like structures within the rings. Sometimes moons or planets outside the ring system will resonate (synchronize their orbital period) with the ring, amplifying the gravitational effects on each other and often causing the formation of gaps in the absence of embedded moons.
Similarly to these moons, comets can also affect the ring structure of a planetary ring. The gravitational effect of a comet causes a wobbling effect on the ring structure when passing close to it, temporarily affecting its very flat shape, creating ripples across it. (Similar to dropping a rock (comet) in a pond and observing the disturbance (ripples) on the surface (ring system) of the pond)
Now that we are more familiar with planetary rings and how they work, what exactly can we do with such information?
Dr. Sutton introduces us to his most recent research on the exoplanet J1407b (the first exoplanet with a ring system to be discovered!) [1] Data collected showed a gap within J1407b’s ring system, and we now know that either means an embedded moon is within the system creating the gap, or orbital resonance with a moon or planet outside the ring is occurring, creating the gap. Dr. Sutton’s intent was to identify an exomoon creating such gap (for the first time ever!).
Starting by investigating a possible orbital resonance affecting the ring system, by modelling the ring system and simulating a multitude of different scenarios that could lead to such gap as observed, Dr. Sutton concluded that this is highly unlikely as simulation results showed disturbances within the ring system that were not observed by real measurements. With low probability on the orbital resonance front, Dr. Sutton continued his research by means of finding evidence for possible moon formation within this ring system, which showed to be quite difficult due to its inhospitable conditions.
Unfortunately, Dr. Sutton’s conclusions do not seem to lead towards his original intent but nonetheless his research opens a new world of scenarios to what could possibly explain such gap, with many researchers sharing his belief that “Planetary ring systems provide excellent natural laboratories” [2]
[1] J. Winder, “The story of J1407b, the first exoplanet discovered with a ring system like Saturn”, BBC Sky at Night Magazine.
[2] P. D. Nicholson, “Planetary Rings,” Astrophysical Discs - An EC Summer School, Astronomical Society of the Pacific, 1999.
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Presentation: 2/3 - Good grammar and English, title, date and the presenters name stated but should be moved to the start to make it clearer
Content: 3/3 - Seminar content well covered
Context: 2/3 - Context well covered, might be beneficial to expand outside of the presenters own research more
Style: 2/3 - Easy and smooth to read through, subheadings would make it more engaging
External source: 2/3 - Own understanding and research mention but could be expanded on.
Overall a nice read!
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Feedback: The presentation (3/3), content (3/3), context (2/3), style (3/3), and external source (2/3) are all great. Most aspects of the mark scheme are included, having mentioned the date, title, speaker name, good grammar and a quoted supporting external source. The post was engaging to read and covered a great amount of content. There may be places where information gets slightly technical or wordy, but all areas have been well explained.
13/15