The Terra satellite is designed to study our planet from space, examining the environment over large scales and in high resolution. While passing over south Africa it took this seemingly normal -- if still very beautiful -- image:
I rotated it, so north is to the left. You can see land to the left, the southernmost tip of Africa, called Cape Agulhas. To the top is the Indian ocean, with the Atlantic to the right. A weather system is forming there, and all looks as it should... until your gaze settles all the way to the right (south). Wait... what's the blue swirly thing?
Holy otology! Is that a giant ear?
Nope. It's an eddy, a vortex, in the ocean, probably spun off the ocean current that flows around the southern cape of Africa. These eddies can dredge up material from deeper waters, including nutrients. Phytoplankton in the water feeds of those nutrients, and bang! Plankton bloom.
The plankton flows along with the water, coloring it blue, making it stand out eerily against the water. As I pointed out in an earlier post about these blooms, we can learn a lot about the environment from them. Plankton are sensitive to climate change, for example, and can act as indicators of the water's physical characteristics. [Update (May 3, 2013): I have more details about this (and a new picture!) in a May3, 2013 post.]
When I see an image like this I think of all the funding cutbacks NASA is facing right now -- and yeah, I'll be writing about that soon. Our planet is on a cusp right now, and I can't help but fret about the opportunities we might miss if we step back from space. Exploring space, even just being in space, has given us a perspective on our home world we couldn't possibly have achieved otherwise. Some things, once begun, shouldn't be stopped. Try as they might, some politicians can't make us unsee what we've seen, and unlearn what we've learned.
Unless we let them, of course. I won't, and I hope you won't either. Let the picture above serve as a reminder: when it comes to keeping track of the Earth, we have to keep our eyes and ears open.