The twin Mars Exploration Rovers, Spirit and Opportunity, have been crawling around the surface of Mars since early 2004 – years longer than they were expected to live. And what they have discovered there on Mars has given scientists their best understanding of Martian geology over the last few billion years. Let’s investigate these amazing rovers and their ongoing mission.

We don’t like cover news on Astronomy Cast, but sometimes there’s a news story that’s interesting, complicated, and rapidly unfolding – and it happens to cover an area that we haven’t talked much about. So today we thought we’d talk about the discovery of arsenic-based life, and exotic forms of life in general. Maybe we need to redefine our definition of life. Or maybe we just got introduced to some distant cousins.

AstronomyCast 208: The Spitzer Space Telescope

Last week we talked about Lyman Spitzer, and this week we’ll take a look at the orbiting observatory that bears his name: the Spitzer Space Telescope. Designed to see into the infrared spectrum, Spitzer has returned images of objects that were previously hidden to astronomers by thick shrouds of gas and dust.

AstroCast 207: Lyman Spitzer

Time for another action-packed double episode of Astronomy Cast. This week we focus on the Lyman Spitzer, a theoretical physicist and astronomer who worked on star formation and plasma physics. Of course, this will lead us into next week’s episode where we talk about the mission that bears his name: the Spitzer Space Telescope.

AstronomyCast 206: Fission

AstronomyCast 205: Fusion

Last week we talked about fusion, where atoms come together to form heavier elements. This week, everything comes apart as we talk about nuclear fission. How it occurs naturally in the Universe, and how it has been harnessed by science to produce power, and devastating weapons.

When the Universe formed after the Big Bang, all we had was hydrogen. But through the process of fusion, these hydrogen atoms were crushed into heavier and heavier elements. Fusion gives us warmth and light from the Sun, destruction with fusion bombs, and might be a source of inexpensive energy. We'll also look into the controversy of cold fusion.