How did water arrive on planet Earth?

Today, we learn just how much water Earth has (spoiler: probably not as much as you'd think), and where it came from in the first place. We'll take a joyride around the early solar system, learn how our stellar neighborhood is like a snow-capped mountain, and discover how the planet Jupiter might have played a crucial role in creating the oceans of Earth.

Extra credit: Drink some water, make a snowball, or watch the Kevin Costner classic Waterworld.

How do we know when the first oceans existed?

Water leaves its' fingerprints over every surface of Earth, even in the oldest, toughest crystals. Today, we'll take an imaginary ride through the earliest oceans, examine how water slowly transforms everything it touches, and how these changes are recorded in the Jack Hills zircons, 4.4 billion years ago.

Extra Credit: Make an underwater rock garden, walk into a muddy beach, or visit a dog park.

How and where did the first cells form on planet Earth, 4 billion years ago?

To answer that question, we investigate why oil and water hate each other, explore the seafloor with the Titanic's discoverer, and take a relaxing dip inside a hot spring.

Extra credit: drop some olive oil into water, or make a trip to the closest hot spring in your local area.

Season 1 Finale.

What was the first living thing on Earth, when did it live, and what did it do?

Today, we end Season 1 by meeting LUCA, the oldest ancestor for every living thing on Earth today. On the way, we'll tackle how complex life formed in a chaotic universe and why it hasn't formed again, take a trip down life's family tree, and meet a deadly modern microbe- one of the closest relatives of the oldest living thing.

Thank you all for listening to Season 1, and stay tuned for Season 2!

Extra Credit: Take a look at family photos, or check your canned foods for botulism.

How old is the oldest slice of Earth's seafloor? The answer is more contentious than you would think. Today, we visit one of the most debated locations in the show: a small island off the Greenland shore named Akilia. Everything about these rocks has been contested, and we'll meet three scientists who form cornerstones of the debates.

Extra Credit: Watch something on an old CRT TV, or count tree rings in a stump.

In 1991, a mysterious, striped red and gray rock was discovered on a cold Greenland isle. Years later, this rock would rock the scientific world with multiple debates about the early oceans and life. What exactly is this rock, and why do we care? Stay tuned, and on the way, we’ll learn how scientists can officially argue with each other.

Extra Credit: Eat something with peanut butter and chocolate, or pet a large and a small dog.

Nearly 30 years ago, one paper claimed to find the oldest evidence for life on Earth. How does that evidence hold up in 2025? Are these fossils or duds? Don’t panic, we’ll answer these questions to life, the universe, and everything in due time. Along the way, we’ll meet the most abundant mineral in the human body, an important fertilizer, and finish a trilogy of intense debates over a small Greenland isle.

Extra Credit: Read The Hitchhiker’s Guide to the Galaxy, eat cake with sprinkles, and make sure to floss afterwards.