“On Jan 30, 2014, beginning at 8:31 a.m EST, the moon moved between NASA’s Solar Dynamics Observatory, or SDO, and the sun, giving the observatory a view of a partial solar eclipse from space. Such a lunar transit happens two to three times each year. This one lasted two and one half hours, which is the longest ever recorded. When the next one will occur is as of yet unknown due to planned adjustments in SDO’s orbit.
Note in the pictures how crisp the horizon is on the moon, a reflection of the fact that the moon has no atmosphere around it to distort the light from the sun.
The sun emitted a mid-level solar flare, peaking at 11:11 a.m. EST on Jan. 30, 2014. Images of the flare were captured by NASA’s Solar Dynamics Observatory, or SDO, shortly after the observatory witnessed a lunar transit. The black disk of the moon can be seen in the lower right of the images.
The movie shows the sun moving quite a bit because SDO has a hard time keeping the sun centered in the image during a transit, because the moon blocks so much light. The fine guidance systems on the SDO instruments need to see the whole sun in order keep the images centered from exposure to exposure. Once the transit was over, the fine guidance systems started back up, once again providing steady images of the sun. “