Earth’s Evolution

You can’t let earth out of your sight for a second. Just when you think you know the look of your coastline, the lay of your forests, the reach of your glaciers, they go and change on you. That was true even before humans arrived, but our constant building, drilling, clear-cutting and climate changing have accelerated the process.

The past 40 years of that relentless terraforming have been captured by the Landsat satellites, which have been in orbit since 1972. Millions of the pictures they’ve taken since 1984 have been digitally cleaned up by Google, and a sampling is being shared exclusively with Time. The clarity of the pictures is extraordinary. A high-definition TV image contains about 2 million pixels; a Landsat frame weighs in at 1.8 trillion.

But the images have more than just aesthetic value. Mexico has enlisted Google to help it survey how much of its forest cover remains intact. Researchers elsewhere will have access to the collection too, helping guide land use and environmental policy. You can’t preserve what you can’t see; Landsat makes the home planet more visible than it’s ever been.