Opportunity, one of two rovers launched in 2003, has traversed thirteen miles in the three years it's been on Mars. It's now at the lip of a 14-mile-wide crater named Endeavour. Project leader Steve Squyres discusses the rover's findings and what NASA hopes to learn.

The greenhouse gas emissions from the 55 million tons of food the U.S. food wastes every year add up to to 135 million tons a year. Some foods, like beef, have a much bigger impact on the climate than others.

Guy Raz talks to Joseph Alonso, head stonemason at the Washington National Cathedral, about the damage the building suffered from the Aug. 23 earthquake.

Even though the FDA started allowing makers of foods containing barley and oats to advertise how good they are for the heart a few years back, demand for the crops is still relatively low. We seem to like our meat and potatoes better.

The 2011 British Wildlife Photography Awards feature the U.K.'s resident animals as they roam their terrain and swim in their waters.

Daniel Shechtman's 1982 discovery of quasicrystals fundamentally changed how scientists thought about solid matter. His finding cost him his job at one lab and the eternal ire of chemistry great Linus Pauling. But it also won him the 2011 Nobel Prize for chemistry.

Researchers in New York are reporting that, for the first time, they've used cloning techniques to successfully create human embryos in the lab. Guy Raz talks about the ethical implications of this research with Insoo Hyun, associate professor of bioethics at Case Western Reserve University.

The embryos would not be used for reproduction, but rather for the creation of embryonic stem cells. Many scientists believe that human embryonic stem cells made this way could revolutionize medicine.

Daniel Shechtman's discovery that atoms could fit together inside of crystals in a nonrepeating pattern fundamentally changed the way chemists look at solid matter. His findings were widely criticized at first, and it took years for Shechtman to prove he was right.