Think of some of the nutrients in your daily vitamins: calcium, potassium, iron, zinc. These are four of the 118 chemical elements from which all matter in the universe is made. But what makes the elements themselves? The answer is shining above you in the sky. Indeed, the building blocks of all substances are chemically created in the stars. (Today)

A piece of Mars fell on Morocco in July. But that was just the start of its travels on Earth. (Today)

SAN FRANCISCO -- Venture deep inside the new skyway of the San Francisco-Oakland Bay Bridge, and it becomes clear that the bridge's engineers have planned for the long term. (Today)

This is one of a series presented by the National Aviary. The National Aviary works to inspire respect for nature through an appreciation of birds. (Yesterday)

Norton D. Zinder, a researcher who helped lay the basis for the new field of molecular biology in the 1950s and '60s and who played a crucial role in the politics of decoding the human genome, died on Friday in a nursing home in the Riverdale section of the Bronx. He was 83. (Yesterday)