For the Sept. 3rd How On Earth show we offer two features:
Wildfires Threaten Water Supplies: (start time 5:45) The wildfire burning in and around Yosemite National Park is now the fourth-largest in California’s history. Covering nearly 350 square miles, the Rim Fire is threatening the Hetch Hetchy Reservoir, which supplies residents in the San Francisco Bay Area with most of their water and power. It’s a lot like the 2012 High Park Fire—which sent ash and debris into the water supply of Fort Collins. These fires offer lessons on the risks wildfires pose to reservoirs. Dr. Bruce McGurk, a former water manager for Hetch Hetchy and a water consultant, speaks with How On Earth contributor Brian Calvert about the risks and future prospects.
Comet ISON Cometh: (start time 12:50) Comets have fascinated 
humans for millenia. Aristotle argued comets were hot, dry exhalations gathered in the atmosphere and occasionally burst into flame. Some people thought that comets replenished Earth’s air. Still others believed they were a source of disease. Scientists today study comets because some are thought to be relatively pristine leftover debris from the formation of the solar system. And studying what comets are made of can provide us a glimpse back to the beginning of the solar system 4 billion years ago. Comet ISON, as scientists call it, is one that scientists predict will be relatively easy to view later this year. Dr. Carey Lisse, a senior research scientist at the Johns Hopkins Institute Applied Physics Laboratory in Maryland, speaks with co-host Joel Parker about comet ISON and its fascinating tails. For more information on ISON, go to NASA’s ISON toolkit, and this cool interactive model.
Hosts: Susan Moran, Joel Parker
Producer: Susan Moran
Additional contribution: Brian Calvert
Engineer: Jim Pullen
Executive Producer: Susan Moran
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Noise Pollution (starts at 6:15) – How on Earth’s Shelley Schlender talks with research scientist Larry Finegold about noise pollution and about a workshop being held today in Denver about 
Today we’re joined by Dr. William Alley and Rosemarie Alley to learn about the nuclear waste crisis in the United States. Bill Alley, a distinguished hydrologist, was in charge of the USGS’s water studies at 
Buzz Aldrin’s Vision for Space Exploration (starts at 6:14) Dr. Buzz Aldrin advocates that the United States should not enter a space-race to the moon against the Chinese, or a race to Mars against the Russians, but rather show leadership by cooperating with the major space-faring nations to systematically step across the great void to the Red Planet. This is his personal Unified Space Vision. He is also working toward an independent council, a United Strategic Space Enterprise, that would advise American citizens about the nation’s space policy. USSE experts would draw on a deep knowledge of America’s previous successes and failures to present a unified plan of exploration, science, development, commerce, and security within a national foreign policy context. Buzz shared these visions with How On Earth’s Jim Pullen. Here’s an excerpt from his hour-long discussion with Jim. Stay tuned for the rest of his discussion, in which he shares little-known insights into why Apollo 11, not Apollo 12, was first to land humans on the moon, and never-before-shared honors for Neil Armstrong and Pete Conrad.
Good & Bad Calories (starts at 4:50) Ever since the 1970s, the rise of obesity in the United States has an epidemic. Researchers around the world are trying desperately to figure out why so many of us get fat, and what we can do to change that. A large amount of funding, and support from public health policy, goes toward the hypothesis that we get fat because we eat too many calories and do not exercise enough; when someone eats more calories than they need, the instructions go, they should exercise. That’s “Calories in, Calories Out.” But recently, an expert with a different point of view spoke to a packed audience of doctors, staff and medical students at the University of Colorado Medical Center. The expert is 
