A 20-year view life on Earth, courtesy of NASA satellites. (Videos: NASA)
The time-lapse animation above shows what Earth has been up to for the past 20 years. It's based on data from a fleet of NASA satellites that have been circling the planet since 1997, monitoring the annual rhythms of ice and life.
The animation was recently released by NASA's Goddard Space Flight Center (GSFC), which combined two decades of satellite data into a sweeping global glimpse of life on Earth. It reveals the yearly ebb and flow of ice near the poles, for instance, as well as the seasonal proliferation of plants on land and phytoplankton at sea.
"These are incredibly evocative visualizations of our living planet," says Gene Carl Feldman, an oceanographer at GFSC, in a statement. "That's the Earth, that is it breathing every single day, changing with the seasons, responding to the sun, to the changing winds, ocean currents and temperatures."
Satellites measured life from space as early as the 1970s, NASA notes, but it wasn't until the 1997 launch of the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) that the agency began what's now a continuous, global view of both land and ocean life.
This view is highly valuable for scientists, who can use these data to study the health of forests, oceans, crops and fisheries. But NASA researchers have also noticed long-term changes across continents and oceans, the agency explains in a press release: "As NASA begins its third decade of global ocean and land measurements, these discoveries point to important questions about how ecosystems will respond to a changing climate and broad-scale changes in human interaction with the land."
Satellites are increasingly adept at detecting life from space, looking at metrics like soil moisture or specific wavelengths of fluorescence caused by photosynthesis. And that will be increasingly important in the years to come, as human activity triggers high-speed changes in the planet's interconnected web of life.
"This is the capability that will allow us to understand how Earth's biology responds to a changing planet," Feldman says.
To learn more, check out NASA's gallery of visualizations and this video overview:
And to see a simpler view of a single year on Earth, check out this visualization created from NASA data in 2013 by John Nelson, a user-experience expert for software firm IDV Solutions:
Nelson, who lives in Michigan, offered this explanation for why such a simple glimpse of our planet can be so powerful:
"Having spent much of my life living near the center of that mitten-shaped peninsula in North America, I have had a consistent seasonal metronome through which I track the years of my life. When I stitch together what can be an impersonal snapshot of an entire planet, all of the sudden I see a thing with a heartbeat. I can track one location throughout a year to compare the annual push and pull of snow and plant life there, while in my periphery I see the oscillating wave of life advancing and retreating, advancing and retreating. And I'm reassured by it."
Editor's note: This story has been updated since it originally appeared in August 2013.