How fast is the universe expanding? It turns out this important value, the Hubble constant (H0), is under constant debate. The two main teams have numbers that disagree by over 5 standard deviations! Today on a[s]b, we resolve the Hubble tension once and for all, as Cormac and Kiersten square off in the Great H0 Debate. Cormac comes in with feist and facts while Kiersten engages with rebuttal and reason. In the end, there can only be 1 winner, and that’s for you to decide! Vote here for the winner of the debate, what the true value of H0 should be, and what we got wrong in the episode (we tried our best!). https://forms.gle/3dybtrhysS9Lvia37

Timeline of the Hubble tension: https://miro.medium.com/v2/resize:fit:1400/format:webp/1*oekTYTkZQmw7DxzUaLqDVw.png

Astrobites used for this episode:

https://astrobites.org/2016/04/20/conflicts-between-expansion-history-of-the-local-and-distant-universe/

https://astrobites.org/2020/05/12/magnets-and-hubble/

https://astrobites.org/2021/04/01/south-polarization/

https://astrobites.org/2021/04/27/bursting-the-hubble-trouble-bubble-measuring-h0-with-fast-radio-bursts/

https://astrobites.org/2023/03/29/multi-messenger-constraints-on-the-hubble-constant/

https://astrobites.org/2023/10/04/holy-cow-is-our-journey-through-the-universe-the-reason-for-the-hubble-tension/

https://astrobites.org/2024/04/16/sn_h0pe/

Space sound: https://www.system-sounds.com/earth-day/. Credit: SYSTEM Sounds/Matt Russo/Andrew Santaguida

Article by Subir Sarkhar: https://inference-review.com/article/heart-of-darkness

Cool Wikipedia page Will references: https://en.wikipedia.org/wiki/Numeral_prefix

Chart Kiersten references: https://en.wikipedia.org/wiki/Cosmic_distance_ladder#/media/File:Extragalactic_Distance_Ladder_en.svg

In this episode, we hear about Kiersten and Will’s epic adventures in both hemispheres! Both Kiersten and Will watched the eclipse that passed through North America on April 8, 2024 and are still buzzing with excitement. Kiersten tells us about a recent paper that explores why planets might act so indecisive about sitting between being a super-Earth or mini-Neptune. Will’s astrobite describes a similarly chaotic exoplanetary tale about a very slow moving planet which “came in like a wrecking ball” and “never hit habitability so hard” (everything in quotations must be sung in Miley Cyrus’ singing voice). All in all, we all share a laugh and an emotionally charged episode!

Kiersten’s astrobite: https://astrobites.org/2024/03/28/template-post-22/

Will’s astrobite: https://astrobites.org/2024/03/06/exoplanet-hr-5183-b/

Eclipse XKCD: https://www.explainxkcd.com/wiki/index.php/2914:_Eclipse_Coolness

Eclipse Astronomy Photo of the Day: https://apod.nasa.gov/apod/ap240409.html

Sonification: https://www.youtube.com/watch?v=8al9FRz-VKY

Sonification description: https://www.exploratorium.edu/eclipse/listen-eclipse

Miley Cyrus’ “Wrecking Ball” music video: https://www.youtube.com/watch?v=My2FRPA3Gf8

In celebration of the a-bit-over-a-week after St. Patrick’s (definitely not Patty’s) Day, we bring you another Ireland-related episode. Due to historically unsupported stereotypes about the Irish being lucky, we bring you two astrobites busting with cosmic coincidences and a dash of luck. Kiersten tells about a plucky planet that avoided a hangry host star, while Will brings us yet another binary black hole bonanza. Cormac shares a bit of an infamous Irish space sound that you could call cosmic comic relief. In the spirit of luck, we talk about the role of luck in our own journeys to space and in the field of astronomy as a whole.

This week’s “space sound” - https://www.tiktok.com/@ladbibleireland/video/7278649311334780192?lang=en