Coronal rain like that captured by NASA's SDO in 2012 is sometimes visible after solar eruptions. (Credit: NASA’s Solar Dynamics Observatory/Scientific Visualization Studio/Tom Bridgman, Lead Animator)

While rain on Earth is associated with water, precipitation on the Sun comes as giant clumps of plasma, or supercharged gas, which drizzle down from the star's atmosphere on to its surface. Though coronal rain has been observed on numerous occasions, its source, which researchers believed would help them better understand how the Sun's outer atmosphere, or corona, gets so hot, had never been discovered. Now, thanks to Emily Mason, a graduate student at The Catholic University of America in Washington, D.C., the mystery has finally been solved.