Our amazing planet.

Our Daily Planet: Knut the Polar Bear Dies and an Earthquake in Afghanistan

Each weekday morning, OurAmazingPlanet takes the pulse of the Earth, reporting on natural phenomena and exploration news from around the globe.

Berlin Polar Bear Dies: The world-famous polar bear Knut has died of unknown causes, according to the Berlin Zoo. Knut was 4 years old.

Weather Watchers: More than 20,000 weather stations, many run by amateur meteorologists, are helping the website Weather Underground refine its forecasts.

Golden Wildfire: A large wildfire west of Golden, Colo., calmed down Sunday, but is still a threat to nearby homes on the burning mountains.

Afgan Earthquake: A magnitude 5.8 earthquake rocked the Hindu Kush region of Afghanistan today.

Polar Trek: 42-year-old Swedish explorer Johan Ernst Nilson will soon embark on an expedition from the North Pole to the South Pole.

Previously on Our Daily Planet: Colorado Bike Race and Tropical Storm Cherono

Reach OurAmazingPlanet staff writer Brett Israel at bisrael@techmedianetwork.com. Follow him on Twitter @btisrael.

Brett Israel was a staff writer for Live Science with a focus on environmental issues. He holds a bachelor’s degree in biochemistry and molecular biology from The University of Georgia, a master’s degree in journalism from New York University, and has studied doctorate-level biochemistry at Emory University.