On Oct. 7th, NASA's Solar Dynamics Observatory observed its first lunar transit when the new Moon passed directly between the spacecraft and the sun. SDO's 16 megapixel cameras recorded the event in detail, revealing jagged lunar mountains backlit by solar plasma:

Image
© SDO
Beyond the novely of observing a such an event from space, these images have practical value to the SDO science team. Karel Schrijver of Lockheed-Martin's Solar and Astrophysics Lab explains, "The very sharp edge of the lunar limb allows us to measure the in-orbit characteristics of the telescope--e.g., light diffraction on optics and filter support grids. We can use that information to correct our data for instrumental effects and sharpen up the images to even more detail."

Ralph Seguin, also of Lockheed-Martin, has prepared a movie of the transit which shows the Moon interrupting an eruption on the sun's northwestern horizon. Watch it again. Did you notice the brief blackout near the beginning of the movie? That was the Earth passing in front of the sun just before the Moon did--a double solar eclipse!