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Why NASA’s Sun-Watching Probe Flips Out Twice a Year

Space acrobatics is all part of the job for NASA’s Solar Dynamics Observatory.

As if staring at the Sun isn't intense enough, NASA's Solar Dynamics Observatory (SDO) just did it while simultaneously pulling off a 360 degree spin on one axis. Launched in 2010, the SDO is the most advanced space telescope ever to study the Sun, and has produced a wide variety of insights about our star over its six years in geocentric orbit.

The spacecraft recorded its recent maneuver at extreme ultraviolet wavelengths with its Atmospheric Imaging Assembly instrument, producing this dizzying timelapse of the Sun appearing to roll ominously in space.

The somersault wasn't a test of the spacecraft's acrobatic abilities, but rather, an essential tune-up for its Helioseismic and Magnetic Imager (HMI) instrument. Twice a year, the SDO completes this flip over seven hours, so that the HMI can recalibrate its view of the solar limb—the outer edge of the Sun. Because these stellar limits are so tempestuous and prone to change, the HMI needs to complete a biannual spin in order to capture the full perimeter of the Sun, helping it to refocus and get a better handle on our star's shape.

For us Earthbound humans, spinning around in circles usually results in dizziness and a fuzzier view of the world. But for the SDO, it's a crucial part of staying sharp against the blinding glare of the Sun.