Google Unveils a 3-Decade Time-Lapse of the Earth

By Jeffrey Kluger



It doesn’t pay to take your eyes off the Earth for a second. Look away even briefly and who knows what it will get up to?

That’s not how things usually seem to human beings living on the surface of the planet. The mountain that’s here today ought to be here tomorrow. The river that meanders along the boundary of your state or your nation will be meandering into the future. If you were in orbit, however, things would look very different—especially if you were in orbit for a few decades at a time. Since 1972, the Landsat satellites—a rotating fleet of four different spacecraft—have kept exactly that kind of long-term vigil, circling the Earth and scanning the surface for the incremental ways the human population is changing the only home it’s got. They’ve been aided since 2015 by the European Space Agency’s Copernicus Program and itsSentinel-2A satellite.

In the years all of the satellites have been flying they’ve taken millions upon millions of high-definition images, which NASA and the U.S. Geological Survey (USGS) have collated and assembled into something of a flip book that reveals the slow but steady alteration of our world. What the two science agencies started, the folks at Google have finished, turning the usually choppy, sometimes-hazy images into smoothly streaming videos, revealing decades of topographic changes in 10-second sweeps. (Click for source material).

Those brief glimpses belie the extraordinary amount of computer-engineering muscle that went into making the mini-movies possible. The Google Earth Engine team worked with more than 5.4 million discrete images taken since 1984, and gave each one individual attention. In some, cloud cover had to be scrubbed away; in others missing pixels had to be filled in. In all of the images, there were plenty of those pixels to attend to. The average high-definition TV image is made of about 300,000 individual points of light. The Google time-lapse images pack 3.95 trillion pixels into a single frame.

In 2013, TIME released the first round of Google time-lapse images—revealing the growing sprawl of Las Vegas, the boomtown that is Dubai, the slow death of Alaska’s Columbia glacier. This year we turn our attention elsewhere. In some of those new sites, the changes have been positive ones—the expansion of the Panama Canal, say, as the greatest engineering feat of the 20th century was updated and improved for the 21st.

In other places, the story is more mixed: the new Jirau Dam, spanning Brazil’s Madeira River, may be an unalloyed good for the people who will have new or improved electrical service, but it’s less good for the villages that were uprooted and the 1,400 miles of jungle that were strung with electrical cables to make the project possible. Still elsewhere the story is one of disaster—as it was in Fukushima, Japan, where a 2011 tsunami deluged a nuclear power plant, endangering millions.

It’s an undeniable achievement that we can keep such a close, sharp eye on our world. It will be even more to our credit, however, if that ability leads us to care more for the world too.