Not until the nineteen fifties did scientists, using radioactive dating, place the age of the Earth at over four billion years.

VOA: special.2009.12.01

At least nineteen of the fifty American states are planning to take part in the two thousand ten Earth Hour observance.

VOA: special.2010.03.22

The radio waves are measured when the earth is at two points opposite one another in its orbit.

VOA: special.2009.01.20

Scientists at the Goddard Space Flight Center in Greenbelt,Maryland, found the substance glycine in material brought back to Earth from a comet.

VOA: special.2009.09.30

The exhibit at the Marin Community Foundation will show artwork influenced by the environment and by Earth Day.

VOA: special.2010.04.21

At space agency headquarters, doctors studied his medical condition as the information was being sent back to Earth.

VOA: special.2009.06.24

The lead researcher was Chiching Liu of the Institute for Earth Sciences at Academia Sinica in Taipei.

VOA: special.2009.07.07

Gaylord Nelson later said that "Earth Day worked because of the immediate response at the grassroots level."

VOA: special.2010.04.21

At the equator, where the Earth is widest, fifteen degrees stretches about one thousand six hundred kilometers.

VOA: special.2010.07.14

The report says that, at maximum activity, the small increase in sunshine over several years causes a small temperature increase in Earth's atmosphere.

VOA: special.2009.09.29

At the same time, hot liquid rock from deep in the Earth pushed to the surface.

VOA: special.2009.01.07

"I'm at home,digging in the dirt, or doing something that is very close to the Earth, because that's where I know how to survive."

VOA: special.2009.06.07

Alfred Wegener said the mountains and fossils were evidence that all the land on Earth was united at some time in the distant past.

VOA: special.2010.01.12

Edward Cook works with the Lamont-Doherty Earth Observatory at Columbia University in New York.

VOA: special.2010.05.25

Susan Bass is the vice president of programs and operations at Earth Day Network.

VOA: special.2010.04.21

Project partners include the Earth Institute at Columbia University in the United States.

VOA: special.2009.01.20

They include "The Day the Earth Stood Still" and "Breakfast at Tiffany's."

VOA: special.2011.02.27

It would test flight conditions at the edge of Earth's atmosphere.

VOA: special.2010.07.07

Continents move about the Earth like huge ships at sea.

VOA: special.2010.01.12

At 400 kilometers above the earth, cameras on board the shuttle took pictures of the space station.

VOA: standard.2009.11.30

When not on the slopes, Weibrecht takes classes at Dartmouth College and plans on eventually earning his Bachelor of Arts in earth science.

VOA: standard.2010.02.09

Colin Macpherson, a professor of Earth sciences at Britain's Durham University, says it's impossible to know how long the volcano will continue to erupt.

VOA: standard.2010.04.16

Swan set out to change that. Invited to speak to world leaders at the first Earth Summit in Rio de Janeiro,Brazil, in 1992 he outlined a plan.

VOA: standard.2009.12.10

"Can we get these guys back?" (SAYING) With the world watching, flight controllers at NASA and the astronauts frantically worked to find a way to get them safely back to Earth.

VOA: standard.2010.04.04