The 2012 solar annular eclipse, as seen from near Kayenta, Arizona. The ring in the sky is the Sun.
This is a single exposure.
Even at maximum eclipse, the Sun was far too bright to view unprotected. It was, in fact, too bright to shoot with an unfiltered camera. I tried shooting it at ISO 100, f/45, 1/8000s, but it was still so blown out that the eclipse wasn't visible. Thus, the use of a filter.
In essence, this is a 12-stop grad-ND filter, better known as a piece of welder's glass held over half of the lens aperture.
(Edit: "annular" not "annual" -- stupid auto-correct)