Dr. Pascal Lee tells the story of how he and his collaborators found a new volcano on Mars. He tells us about the "convergence of lines of evidence" that led to this discovery. He also explains why this site may be a good place to look for life.

Astrophysicist Tina Ibsen tells us about the northern lights. She talks about her research and gives tips on how to observe the lights. She tells us how Denmark is a space nation and shares her thoughts about the future of space exploration. We also talk about RumSnak, the space podcast she co-hosts with Anders Høeg Nissen.

Dr. Carrie Holt talks about how she's getting ready for the Legacy Survey of Space and Time (LSST) by the Vera C. Rubin Observatory. She explains how astronomers are using simulated and real data to prepare in advance of this new data.

Carrie chats with Anders and Tina on the beautifully produced Danish space podcast, RumSnak. The show starts with space news in Danish before the mostly English interview, which starts 24 minutes in. Find RumSnak on your favorite podcatcher, or online at www.rumsnak.dk.

Dr Tracy Becker tells us about solar system science using ultraviolet light. She explains how the color of a planet's northern lights depends on the planet's atmosphere. She also describes how scientists repurposed the New Horizons spacecraft to measure how empty space is.

Professor Thomas Tauris explains what gravitational waves can tell us about colliding neutron stars. He corrects Carrie's misconception about how gravitational waves affect people. He also explains how the last 400 years of astronomy have been like watching a silent movie, but now with gravitational waves, we have a soundtrack.

Prof. Sabine Stanley, author of "What's Hidden Inside Planets," tells us how the interior of Earth helps make this planet a nice place to live. She tells us that the Earth's mantle is actually solid rock, not liquid rock. She also explains what the Earth's interior and birthday balloons have in common.

Spacepod listeners can get a 30% discount on "What's Hidden Inside Planets" with the code HPLAN if you order through Hopkins Press at press.jhu.edu. (This code is shared as a courtesy, Spacepod does not receive compensation if you order a book.)

Dr. Jon Merrison talks about the Mars Simulation Laboratory. Here, scientists study what happens in low temperature, low pressure, windy environments. He says visiting scientists often "come to our lab with some idea based on the conventional model and go away with data which makes no sense to them."