Images: NASA/Animations: John Nelson

These animations don't show us anything we didn't already know. Earth always grows icier in winter and greener in summer (even if climate change is beginning to tweak that balance). But they're still mesmerizing. They let us see the slow, enormous pulse of our planet's seasons all at once, in just a few seconds, over and over and over.

NASA satellites took these images, but they were stitched together by John Nelson, a user-experience expert for software firm IDV Solutions. Nelson, who lives in Michigan, offers 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."

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