Dr. Debbie Weiser talks about human-made earthquakes on my favorite planet, Earth. She explains how seismologists try to distinguish between natural earthquakes and those caused by human activity, and why the earliest seismometers in California were installed by astronomers.

Dr. Driss Takir stops by the show. He explains how he looks for water that's molecularly bound up in the rocks on asteroids. He also tells us about the Hayabusa-2 mission, which will put rovers on the the surface of asteroid Ryugu.

Dr Jennifer Scully talks about the geology of Ceres and Vesta, two large asteroids in the main belt that have been visited by NASA's DAWN mission. She's talks about the experience of getting to know each and every crater, and why the first images from Ceres surprised some people.

Dr. Shantanu Naidu tells us about planetary radar. Using large telescopes in California and Puerto Rico, he bounces radio waves off of asteroids and "listens" for the return signal. With this technique, he's discovered moons on several asteroids.

Dr. Sona Hosseini talks about spectroscopy, a technique that allows scientists to determine what celestial bodies are made of. She's developing new spectrometer that will allow her to look at an entire planet, or comet, all at once.

Dr. Dave Reitze, the Executive Director of LIGO, talks about how each source of noise at LIGO must be meticulously accounted for— from wolves howling, to tidal flexing of the Earth's surface, to the motion of the atoms in the observatory's mirrors.

Dr. Dave Reitze, the Executive Director of the Laser Interferometer Gravitational-wave Observatory (LIGO) talks about the extraordinary detection of gravitational waves earlier this year, and the incredible engineering that made it possible.

Dr. Varoujan Gorjian thoroughly debunks a misconception he hates— the idea that black holes suck. Find out what would happen to the Earth if our Sun was suddenly replaced with a black hole of the same mass, and why is is so challenging to send a probe to Mercury.

Dr. Marja Seidel stops by the show to talk about galaxy evolution. She also talks about a unique outreach effort she co-founded, called Cielo y Tierra, that shares science with remote communities.

Dr. Andrew Benson talks about dark matter, the mysterious stuff that makes up most of the mass of the universe. Andrew explains how we can learn about dark matter, even though we don't yet know what it is.