Sun Mosiac
NASA compiled past images to re-create the 100 millionth photograph taken by the Atmospheric Imaging Assembly aboard the Solar Dynamics Observatory. NASA/SDO/Mosaic Created with AndreaMosaic

NASA's Solar Dynamics Observatory, or SDO, is celebrating its fifth anniversary. The U.S. space agency's workhorse solar observation satellite was launched Feb. 11, 2010, from Cape Canaveral Air Force Station in Florida and has been taking photographs of the sun practically every second of every day.

Last month, the SDO's Atmospheric Imaging Assembly snapped its 100 millionth photo of the sun. The AIA and two other instruments take 57,600 photos and send 1.5 terabytes of data back to Earth every day. The three instruments allow the SDO to observe its subject in different spectrums. They provides detailed observations of the sun's surface, its outer atmosphere layer, or corona, and the extreme ultraviolet rays that it emits. The AIA is best known for its ability to capture coronal mass ejections, or CMEs, and solar flares.

"This mission has touched us on many levels; it evokes a sense of wonder when we see these beautiful images. It stokes our curiosity and it connects us personally to the deepest mysteries -- from the warmth we feel on our skin when we walk outside on a sunny day to the distant reaches of the cosmos," Lika Guhathakurta, SDO program scientist at NASA headquarters in Washington, said in a statement.

The SDO routinely observes solar activity, sunspot growth and the sun's magnetic field. One of the great mysteries of the sun centers on why its atmosphere is as much as 1,000 times hotter than its surface. On Earth, it's the converse, and scientists are using the solar observatory's data to better understand the heat-transfer process. Data collected by the SDO has led to a boom in scientific research, with more than 2,000 papers published using its observations. "SDO has also led to wonderful international collaborations, with the data being shared and used all over the world," said Dean Pesnell, SDO project scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland.

You can monitor SDO's daily observations of the sun here.