Alan Friedman's shot of the solar prominence was not the only amazing picture he took of the Sun last week. He also caught something pretty special: the Orbiter Discovery, docked with the International Space Station, as the pair crossed the face of our star:
Amazing. He had to rush from giving a talk, drive to the location, set up, and be ready to snap this event... which lasted only a fifth of a second! As it was he barely made it; had he missed his location by a few hundred meters the docked spacecraft would've been off to the side of the Sun. He took this picture on March 1, 2011, a week after launch, midway through Discovery's final mission.
The Orbiter is on the bottom of the ISS as seen here; I drew a line pointing to it in this zoomed shot (the configuration is clearer in this picture from last year of the ISS and Atlantis transiting the Sun by the always-amazing Thierry Legault). To give you an idea of the scale, the ISS is about 100 meters long, about the length of an American football field from goal post to goal post, and orbits the Earth at a height of 350 km (210 miles). The Sun is 1.4 million km (860,000 miles) across and 150 million km (93 million miles) away.
What does that all mean? Well, see that sunspot cluster on the left? It looks to be about the same apparent size as the ISS... but it actually spans a region as big as Jupiter!
This is the final flight for the Orbiter. Discovery is scheduled to land in Florida tomorrow, Wednesday, March 9, 2011, just before noon local time. That means that Alan's picture shows, almost literally, Discovery's last moments in the Sun.