At the XXVIth General Assembly of the International Astronomical Union, held in Praague in August 2006, a new set of three criteria were decided to define what is — and what is emphatically *not* — a planet. Infamously, Pluto fulfilled only two of the three criteria, and so was unceremoniously dumped from the planet club, and reclassified as a "dwarf planet". A decade later, the New Horizons spacecraft swung past this tiny, frozen rock on the outskirts of the Solar System and reported back that Pluto is actually a pretty fascinating place, with a loads of cool suface features and even a thin atmosphere capable of creating dunes of solid methane! Dwarf planet it may be, but Pluto is still awesome.
Syzygy is produced by Chris Stewart and co-hosted by Dr Emily Brunsden from the Department of Physics at the University of York.
To view the podcast chapter list and artwork in this episode, you could do worse than use the Overcast app on iOS, or Pocket Casts on Android. (Other podcast players are available, though they may not handle mp3 chapters nicely.)
Some of the things we talk about in this episode:
The "Dunes on Pluto" paper: http://science.sciencemag.org/content/360/6392/992
A good article about the paper: https://cosmosmagazine.com/space/scientists-unlock-the-secrets-of-pluto-s-methane-dunes
All about Pluto from NASA: https://solarsystem.nasa.gov/planets/dwarf-planets/pluto/overview/
When I was your age, Pluto was a Planet! https://www.redbubble.com/people/kipstewart/works/3024944-when-i-was-your-age-pluto-was-a-planet?p=t-shirt
Why Pluto is no longer a planet: https://www.universetoday.com/13573/why-pluto-is-no-longer-a-planet/
How Pluto got its name: https://www.smithsonianmag.com/smart-news/how-pluto-got-its-name-180955912/
The Kuiper Belt: https://solarsystem.nasa.gov/solar-system/kuiper-belt/in-depth/
The New Horizons mission: https://www.nasa.gov/mission_pages/newhorizons/main/index.html
Images of Pluto, before and after New Horizons: https://blogs.nasa.gov/pluto/2016/08/04/pluto-what-a-journey/
Pluto ... or Pluto™? https://twitter.com/ekaschyk/status/620967219934154752
Images of the Dunes on Pluto: http://science.sciencemag.org/content/360/6392/992/tab-figures-data
Astronomer Sir Patrick Moore: https://en.wikipedia.org/wiki/Patrick_Moore