Sharmila Kuthunur

From lava fields in Idaho to deserts of Chile, NASA sought out some of Earth’s most extreme landscapes to simulate surfaces of other planets.

On August 20, 1975, Viking 1 was launched to Mars and approximately 10 month later, it relayed its first images from the Red Planet. Those images revealed a desert-like world—and hints of possible life.

For decades, humanity has searched for signs of alien life, but many have been disproven or remain inconclusive.

Despite its timeless appearance, the moon has not always been in Earth's orbit, and scientists continue to investigate its true age.

Here is the origin story of Earth—the only place we know life to exist.

Early in its existence, massive asteroids smashed into Earth with lasting consequences for our planet’s geology and life.

Global cooperation, starting in the late 1980s, helped heal Earth’s damaged ozone layer and steer it toward recovery.