On Sunday I posted about NASA's twin STEREO spacecraft, which are now 90° ahead and behind the Earth in its orbit. From their vantage point, over 200 million kilometers away, they can together see the entire far side of the Sun and beam the images back to Earth, providing us with real time data impossible to get from home. While I was going through old blog posts to look at entries I had written about STEREO, I found one showing some STEREO data that I thought was worth showing everyone again. Putting it in Sunday's article would've made it too long, so here it is on its own. Let me interject a personal note first. I was at NASA's Goddard Space Flight Center working on Hubble when STEREO was first being put together as a mission. I remember thinking how cool it would be to see the entire Sun at the same time, and what it would mean to my friends over at the heliospheric physics section. I have a decent imagination, but still there was no way I could've ever foreseen some of the things STEREO has brought us -- Nature is always more clever than any one of us. And my favorite of all of them, sent back while the two spacecraft were still relatively near the Earth, is this incredible animation showing something that can never be seen from Earth: the tiny disk of the Moon transiting the Sun:
From Earth, that would be a solar eclipse, where the black disk of the Moon would look the same size as the bright Sun. But from well over a million kilometers away -- the distance STEREO B was when it took these images -- the Moon is smaller, providing this eerie and beautiful view that is a stunning reminder that humans are a spacefaring species, and the views we get from there expand our world.