How Planets Live and Die, with Sam Grunblatt

What’s going to happen to our planet Earth when our Sun turns into a red giant? Dr. Charles Liu explores planetary evolution and death with exoplanet specialist Sam Grunblatt, the Kalbfleisch postdoctoral fellow at the American Museum of Natural History Department of Astrophysics, who studies planetary archaeology and stellar astrophysics, and co-host Allen Liu. Sam’s most recent paper is about “hot Jupiters” at the end of their lifespans, racing around their stars in orbits just a few days long.

As always, though, we start off with the day’s joyfully cool cosmic thing: the discovery of a third “planetary candidate” orbiting Proxima Centauri, the closest star to our sun. And while these planets might not be able to sustain life, the news is the latest discovery in our developing understanding of stars and exoplanets. Proxima is a red dwarf star that’s in a system with two other stars that are more like our sun, and which may also be hosting their own planets! (And yes, Tatooine gets mentioned yet again, along with a juicy Isaac Asimov reference.)

Before we get to our questions, though, we take a break for a musical interlude celebrating the solar discovery. It turns out that Sam was the Musical Director for the Columbia Kingsman a cappella group, and given that Allen was also the Musical Director of an a cappella group that was part of the Harvard Glee Club, Charles couldn’t resist corralling the pair for a trio.

Our first student question, from Nora in New York City, is about “mini-Neptune exoplanets turning into Super-Earths.” Sam explains how the most common exoplanets we’ve found are either rocky bodies slightly larger than Earth, or gas giants that are much larger than Earth but smaller than Neptune, and the possibility that stars strip the atmosphere’s of the gas giants away leaving just the rocky cores.

Next, the trio discuss “Don’t Look Up,” the recent movie ostensibly about the discovery of an asteroid that threatens Earth, but which was really an allegory about climate change and how we humans deal with science and non-science in our lives.

Cody from New York asks whether planets in other solar systems are mostly on the same plane as they are in our solar system. Yes and no, according to Sam. Sometimes they are, but also frequently their orbits don’t line up in the same horizontal plane, and in some extreme cases, they’re wildly divergent.

Finally, Sam shares his favorite exoplanet with us, which was discovered by the TESS (Transiting Exoplanet Survey Satellite) space telescope. TOI-561b is a Super-Earth that might still have an atmosphere. one of the first exoplanets we’ve found in the “thick disk” of our galaxy.

We hope you enjoy this episode of The LIUniverse, and, if you do, please support us on Patreon. Also, if you want to follow Sam, check out his website [INSERT LINK: >] or follow him on Twitter @skgrunblatt.

Credits for Images Used in this Episode:

Size of the Sun as a Red Giant – Credit: Oona Räisänen, Mrsanitazier CC BY-SA 3.0

Earth, Neptune, and Super-Earth to scale – Credit: Aldaron, CC-BY-SA 3.0

Solar System Illustration – Credit: NASA's Scientific Visualization Studio, Public Domain

TESS Spacecraft Before Launch – Credit: NASA, Public Domain