The Importance of Planetary Rings as Astrophysical Laboratories
Saturn has famously large rings, visibly spanning over 250,000Km[1] (and up to millions of Km for the fainter outer rings[2]), but did you know that stars and even asteroids can also have rings? Dr Phil Sutton explores astronomical ring systems around the universe in his seminar “The Importance of Planetary Rings as Astrophysical Laboratories”, delivered on 15/10/25, with focus on his work on exoplanetary ring systems (planets not within our Solar System). Evaluating the largest ring system ever found on an exoplanet, lying over 400 light years away![1]
Rings are everywhere in space (even Jupiter and Uranus have their own ring systems) and they are crucial in the formation of star systems, planets and moons. We define rings as a collection of separate particles orbiting in a common direction. As planets spin their centripetal force causes a bulge at their equators, this means more gravity acts there, pulling any debris into a flat line about the planet’s centre of spin, forming a ring.
Any particles moving in other directions eventually crash into particles within the ring, knocking them both out, thus removing particles orbiting in a different direction to the rest of the ring. This is why ring are always circular and there can only ever be a maximum of one ring around a planet.
Some of the particles within rings can clump up due to gravity, forming planets around stars or moon around planets, these form gaps in the ring system or can use the ring up entirely. Due to the higher gravity of the moons or planets their gravity offsets and ‘wobbles’ the ring system, this is detectable and is actually how a lot of moons are found, even if we cannot see them.
Phil talks about how he was looking at the largest ring system around a planet ever discovered, orbiting J1407b which is a brown dwarf that’s 20 times more massive than Saturn, lying 433.8 lightyears away![1] Its rings are estimated to be a whopping 180,000,000Km wide, putting Saturn’s to shame by about 200 times. The exoplanet was discovered by analysing abnormal light curves from its parent star J1407 (creative, I know), which is where the light from the star dims for a period of time due to a planet (and its rings) travelling in front of it, blocking its light - which can be measured.
Dr Sutton explains his work in trying to be the first to ever discover an exomoon, using J1407b as his exoplanet of choice due to its large rings. Due to the planet’s highly elliptical (non-circular) orbit around its star, its rings are very fragile and aren’t friendly to moon formation. Phil’s simulations show that a ring system around the planet is only stable if the rings orbit opposite to the planet’s rotation (retrograde), which is rare and only caused by large events like collisions or a former moon being ripped apart. The gaps measured within the ring system likely that moons are creating them as their gravity pulls on the ring at regular intervals in its orbit, this is called orbital resonance. Using the resonance and eccentricity (how elliptical the orbit is) data Phil found where an exomoon should be, however evidence concluded that a moon being in this spot counteracts other observations of the ring system and thus is likely not to be there.
Other astronomers have tried to see if J1407b is even a planet at all, or if it even orbits the presumed parent star. Perhaps it was pure coincidence that the planet was seen in a light curve of the J1407 star, or perhaps it was just passing close to the star system without actually being in orbit around it. Scientists are still finding out everything they can about this unique exoplanet, with it inspiring more work in the exoplanet field each day. BBC Sky at Night Magazine[3] claims over 6000 exoplanets have been discovered as of summer 2025, with only more to be discovered as more research is put into this exciting field.
Perhaps one day we will see exomoons, or perhaps we may even see another planet like Earth.
References:
[1] https://www.skyatnightmagazine.com/space-science/j1407b
[2] https://www.britannica.com/place/Saturn-planet/The-ring-system
[3] https://www.skyatnightmagazine.com/space-science/direct-images-exoplanets
42890
Good mix of information and captivating language, it is very concise and also clear you understand this very well
94931
Following the Module Handbooks five criteria.
Overall presentation 2/3 to improve add date of the seminar
Accurate report of take home message 3/3
Accurate contextulasation 3/3
Additional Assessment from external source 3/3
Writing Style and Technical Level. 3/3
Very Good to me.
76354
A really good balance of keeping the scientific content whilst being accessible for a lay audience, e.g. still using phrases such as elliptical orbit but just simply putting non-circular in brackets helps anyone understand what is being explained, or defining retrograde easily! Good references used as it shows extra research whilst being interesting facts to remain engaging :-) Overall good grammar, presentation and many areas from the seminar covered concisely.
46422
Brilliant job on concisely explaining the information in an engaging way. Technical ideas are introduced allowing those with a scientific background to easily find out more, and explained well in lay terms keeping it accessible to all audiences. Good use of external sources to elaborate on ideas introduced in the seminar. I’d say its a high quality blog post, there are some small nitpicky issues like ‘.Evaluating the largest ring system ever found on an exoplanet, lying over 400 light years away![1]’ doesn’t make sense as a sentence, but I imagine this was supposed to be a comma instead of a fullstop. Other than the small issues with clarity it’s great.
Overall presentation 2/3 - to improve make some small grammatical changes, add date of seminar
Accurate report of take home message 3/3
Accurate contextulasation 3/3
Additional Assessment from external source 3/3
Writing Style and Technical Level. 3/3
41058
Presentation: Title and speaker name can be seen. As improvement I would recommend adding the date of the seminar too. Grammar and English are good, however there is just one type I noticed in the sentence ‘This is why ring are circular’, ‘ring’ should be ‘rings’. The blog can be read smoothly and paragraphs are structured well.
Content: Key themes of the seminar have been summarised in detail to allow for a smooth and accurate read and a good understanding of the content.
Context: Research context is well explained. Current work in astrophysics is described mentioning important observations. Societal context mentioned too such as how these discoveries are important to the field. However, possibly mentioning a little more on the beneficial effects of the research for society could be a good idea.
Style: The style is informative and easy to read so engaging to those that don’t know much on the topic. Some humour has been added in making it an engaging read and appropriate and accessible to a range of audiences.
External Source: There is evidence of research done outside of the seminar with good use of referencing from relevant sources. References also used in the text, e.g. [1], to make it easy for readers to find the sources used for a specific piece of work of information if they wanted to.