May 31st 2026

Things from Today:

• "Where do Saturn's rings come from?" - This is a question I couldn't give a satisfactory answer to at the time. I was aware that Saturn's rings are mostly ice (although, I didn't realise they are nearly 99% ice, and only 1% rock!). The structure of the rings is also far richer than I was aware of - with parts of the B ring featuring 'mountains' of debris over one and a half miles tall (in contrast to the remarkable flatness and narrowness of much of Saturn's ring system). This video featuring renowned Saturn specialist, Carolyn Porco,  gives a great visualisation of how these 'mountains' might look up close.
  One of the key phenomena responsible for the formation of Saturn's rings, are so called gravitational tidal forces. As the name might suggest, these kinds of forces are also the cause of the Ocean tides we have on the Earth; however, they are responsible for many different phenomena.
  A tidal force is the name we give to the strain that is present on a body, when it is placed in a gravitational field whose strength varies over the length of that body. The closer you get to a source of gravity (e.g. the surface of Saturn), the stronger that gravitational pull becomes. If an icy moon entered Saturn's orbit too close to the planets surface, the strength of gravity pulling on the near side of the moon would be far stronger than the gravity pulling on the far side. This difference in gravity creates a tension across the moon, which may lead to a tidal disruption, ripping the moon apart and leaving behind a ring of icy shrapnel. This is precisely what astronomers think must have happened to form large parts of Saturn's rings.
  However.. this is not the full picture. There are multiple processes that contribute to the formation of Saturn's rings, including the continuous cryovolcanic feeding of the E ring from Saturn's inner Moons.
  This was such an interesting topic, I have included a number of links in the Extra Reading and Extra Watching / Listening sections if you want to learn more.
  Thank you for the question, Rory!

• "What is your Favourite Subatomic Particle?" - As a particle physicist, I should perhaps be a little embarrassed that this question had never occurred to me! After a little bit of thinking, I settled on the Muon.
  The Muon is essentially a heavier cousin of the Electron (Electrons being the particles that orbit around the nucleus of the atoms in the regular matter we see around us).
  As the Muon is over 200 times heavier than the Electron, it is inclined to decay into an Electron (+ some other products) with an average lifetime of about 2.2 millionths of a second.
  What I find most interesting about Muon's is how they directly demonstrate Einstein's special theory of relativity - specifically, the concept of time dilation: the crazy (but totally correct!) idea that a moving clock ticks more slowly than a stationary clock.
  Muons are produced in the upper atmosphere of our planet when Cosmic Rays (very high energy charged particles originating outside of our Solar System) ricochet off our atmosphere.
  Even though these atmospheric Muons travel at a speed very close to the speed of light, the time it would take for them to reach the Earth's surface is still far longer than 2.2 millionths of a second (a Muon's lifetime) - so, you might not expect many Muons will make it all the way down to the Earth's surface before turning into Electrons. But... We detect a awful lot of Muons on the Earths surface!
  As the Muons travel so quickly, their 'internal clock' ticks far slower than our clocks on the Earth. So, although we might measure the Muons journey time between the upper atmosphere and the Earth's surface as being longer than then Muon's lifetime - that is not what the Muon's perceive (which is the time that matters!), due to Einstein's time dilation effect.

Extra Reading:

• [Article] Why Do Some Planets Have Rings and Others Don't? - K Howells & A Stahl (The Planetary Society)

• [Article] Cryovolcanism in the Solar System - E Pearson (Sky at Night Magazine)

Extra Watching / Listening:

• [Podcast] An Astrobiologist Pieces Together How Life Started - B Kaçar (StarTalk)

• [Video] How Saturn Got Its Rings | The Planets | BBC Earth Science - BBC Earth Science

• [Video] Neil Turok on How Theoretical Physics Went Wrong and Why Universities Don’t Encourage Originality - London Institute for Mathematical Sciences

Homework

This 'homework' is recurring, and one I like to set my own students (and try to stick to myself!):

1. Learn something new everyday.

2. Share what you know with someone else.

3. Look at the world and "think like a Martian".

If you learn something interesting, I would love to hear about it! Tell me about it next time or drop me an email!

spacetime-sundays@science-on-sea.com