Earth

Cradle of Life As We Know It

Earth is the only place we know of in the universe that harbors life. Ours is the largest terrestrial planet in the solar system. Our rocky, volcanic world is coated in a thin veneer of liquid water, living things, and translucent atmosphere, whose complicated interactions make Earth's surface into a place of constant change. We humans have only had fifty years of perspective on Earth as a planet, of seeing it as a "pale blue dot" floating in the black vacuum of space.

With that perspective, we know precious and unique our planet is. We know, too, that we are having measurable effects on the complex interactions of ocean, land, life, water, and air, changing our climate. But predicting the future of our climate is hard. Understanding how Earth's systems work by studying the way they operate on other worlds is a major goal of planetary exploration. Mars, Venus, and Titan all have (or had) active geology, hydrology, and weather -- but, as far as we know, they don't have life. Is Earth really that unique? Are we truly alone in the universe? We won't know unless we keep searching.

News from Earth

Parallel planetary processes create semantic headaches

Posted by Emily Lakdawalla on 2012/01/26 03:55 CST

I ran into a semantic problem today: what to call the science of studying liquids on Titan?

Steno's principles and planetary geology

Posted by Emily Lakdawalla on 2012/01/11 12:29 CST

The Google Doodle for January 11, 2012 celebrates Nicholas Steno, one of the founding fathers of modern geology, on the occasion of his 374th birthday. This article describes Steno's set of rules that guide geologists in reading rocks to tell the story of how a place came to be and how the rules are currently used in geology.

The Earth from GOES-East in visible and infrared

The state of Earth observation, January 2012

Posted by Jason Davis on 2012/01/09 05:54 CST

As of November 2011, the Earth Observing Handbook counts 109 active missions to study the Earth as a planet, with 112 more approved and planned for the future. Jason Davis provides an overview of key current and upcoming earth-observing missions.

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Taken by Voyager 1 on February 14, 1990 from a distance of more than 6 billion kilometers and about 32 degrees above the ecliptic plane. In the image the Earth is a mere point of light, a crescent only 0.12 pixel in size. Our planet was caught in the center of one of the scattered light rays resulting from taking the image so close to the Sun.

A Pale Blue Dot

Look again at that dot. That's here. That's home. That's us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives.

Voyager 1's picture of a crescent-shaped Earth and Moon was the first of its kind ever taken by a spacecraft.

Pictures of Earth by Planetary Spacecraft

Many solar system explorers take dramatic photos of Earth as they depart, or fly by; some even have photographed Earth from the vantage point of another planet.

The state of Earth observation, January 2012