They could compare it with images taken by Earth-based telescopes.

VOA: special.2009.09.30

Newton proved his idea by measuring how much gravity force would be needed to keep the moon orbiting the Earth.

VOA: special.2011.06.01

It has high mountains. It has valleys formed by ancient ice that cut deep into the Earth millions of years ago.

VOA: special.2009.01.07

The first pictures of Earth taken from space showed a solid ball covered by brown and green landmasses and blue-green oceans.

VOA: special.2011.01.04

The ground still shows the path cut deep into the earth by the wheels of thousands of wagons.

VOA: special.2009.03.30

Muse Opiang studied how echidnas eat, by digging in the earth with their long noses to find worms.

VOA: special.2009.07.07

The total energy reaching Earth from the sun rises and falls by just one tenth of one percent across this solar cycle.

VOA: special.2009.09.29

She said the discovery "supports the theory that some of life's ingredients formed in space and were delivered to Earth long ago by meteorite and comet impacts."

VOA: special.2009.09.30

The last one,by astronaut Gordon Cooper, circled the Earth twenty-one times.

VOA: special.2009.06.17

On Earth,it is mainly produced by processes linked to biology.

VOA: special.2009.12.30

Gillian wrote a report of how he spent the thousand dollars: "Paid by Robert Gillian, one thousand dollars on account of the eternal happiness, owed by Heaven to the best and dearest woman on earth."

VOA: special.2011.08.13

As we approached the mountain, the hills and gulleys bore the appearance of having been created by some vast, fierce torrent rushing around the base of the peak, and tearing its way through the loose earth....

VOA: special.2010.04.26

It is rather for us to be here dedicated to the great task remaining before us that from these honored dead we take increased devotion to that cause for which they gave the last full measure of devotion that we here highly resolve that these dead shall not have died in vain that this nation,under God, shall have a new birth of freedom and that government of the people, by the people,for the people, shall not perish from the earth."

VOA: special.2009.11.12

The ONLF accused the troops of conducting a 'scorched earth' campaign, a claim that was strongly denied by the government.

VOA: standard.2009.11.16

The accomplishment was soon followed by cosmonaut Yuri Gagarin's historic manned spaceflight into Earth's orbit in 1961.

VOA: standard.2009.07.16

Television and radio transmitters on Earth may soon go dark, replaced by cable,fiber,satellites, and the Internet.

VOA: standard.2010.04.16

Astronauts began their first full day in space by inspecting the heat shield to ensure the shuttle is safe to return to Earth in two weeks.

VOA: standard.2009.07.16

Both Melvin and Satcher say they hope there will be many more African-American space explorers inspired by what they've accomplished, not only in outer space but on Earth.

VOA: standard.2010.02.02