Yesterday, Nov. 22nd, the Moon passed in front of the sun off-center, producing a beautiful partial eclipse. No one on Earth saw it, because the lunar transit was visible only from Earth orbit. More than 22,000 miles above the planet's surface, NASA's Solar Dynamics Observatory (SDO) snapped this picture:
Using a bank of 16-megapixel cameras, SDO observed the event at multiple extreme ultraviolet wavelengths. Scan the edge of the Moon in the 171 Å high-resolution image, shown below. The little bumps and irregularities you see are lunar mountains backlit by solar plasma:
Beyond the novelty of observing an eclipse from space, these images have practical value to the SDO science team. The sharp edge of the lunar limb helps researchers measure the in-orbit characteristics of the telescope--e.g., how light diffracts around the telescope's optics and filter support grids. Once these are calibrated, it is possible to correct SDO data for instrumental effects and sharpen the images even more than before.