Climate Rally held to honor Earth Day in Washington

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Discovery astronauts begin spacewalk

Astronauts from the Space shuttle Discovery have begun the first spacewalk of their mission. They will install a new tank of ammonia coolant on the International Space Station.

Missing piece in human evolution?

Two skeletons, nearly 2 million years old, are on display in South Africa. They offer a rare opportunity to view a previously unknown species that scientists say fits the transition from ancient apes to modern humans.

Discovery delivers cargo container to ISS

Japanese astronaut Naoko Yamazaki has completed attaching a huge cargo container to the International Space Station.