NASA’s space telescope NuSTAR (Nuclear Spectroscopic Telescope Array), launched in June 2012, was built to study objects such as black holes and for this reason its sensitivity focuses on high-energy X-rays. For once, however, it was used in a way totally different from what was intended to observe the Sun in a new way.

The idea of using NuSTAR to study the Sun came to David Smith, a solar physicist and a member of the NuSTAR team, already seven years ago, during the construction of this space telescope. Fiona Harrison, the project’s principal investigator, initially thought it was a crazy idea but Smith convinced her that it made sense. The purpose of the proposal was to try to observe the faint flashes of X-rays that the Sun emits according to the theoretical predictions.