This movie shows the moon crossing in front of the sun – called a lunar transit – as seen by NASA’s Solar Dynamics Observatory (SDO) on January 30, starting at 8:31 a.m. EST.
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.
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.