In this solar system, Venus is the planet most like Earth in size and density, yet it has a toxic atmosphere and is the hottest planet, contrasting with habitable Earth. Astrophysicist Stephen Kane reveals clues that point to a possible habitable past of Venus and discusses how its environment might have become hostile to life.
Being just the right distance from the sun helps make Earth habitable, but the composition of our atmosphere is a key ingredient. Natalie Burls, the director of the Climate Dynamics Program at George Mason University, discusses the crucial role Earth’s atmosphere plays in determining its climate, how Earth’s climate has varied in the past, and how we are the changing the composition of Earth's atmosphere and thus its climate.
For centuries, people have speculated about the possibility of planets orbiting distant stars, but only since the 1990s has technology allowed astronomers to detect them. Astrophysicist Joshua Winn provides an inside view of the detective work astronomers perform as they find and study exoplanets and describes the surprising—sometimes downright bizarre—planets and systems they have found. He also considers how the discovery of exoplanets and their faraway solar systems changes our perspectives on the universe and our place in it.
Planetary scientist Rebecca Ghent, co-investigator on the Lunar Reconnaissance Orbiter mission, discusses our Moon’s history of impact cratering and examines the significance of the impact record for understanding the evolution of the Moon and other solar system bodies.
Mars is the most explored planet in our solar system besides Earth, and for good reason. Although its surface is cold and inhospitable, evidence from nearly 50 years of robotic exploration suggests that Mars was once much more Earth-like. Katie Stack Morgan, the deputy project scientist on the Perseverance rover mission and a mission scientist on the Curiosity rover mission, explains why Mars remains the best place in the solar system to look for signs of ancient life.
