Hints of Solar Nanoflares

Video Player

Video Versions


Produced by the Space Telescope Science Institute’s Office of Public Outreach in collaboration with NASA’s Universe of Learning partners: Caltech/IPAC, Center for Astrophysics | Harvard & Smithsonian, and NASA Jet Propulsion Laboratory.
Video imagery:

  • Composite image of Sun in X-ray and ultraviolet light: NASA/JPL-Caltech/JAXA
  • NuSTAR high-energy X-ray image of the Sun: NASA/JPL-Caltech

Writer: Leah Ramsay
Designer: Leah Hustak
Science review: Dr. Quyen Hart
Education review: Jim Manning
Music from Music for Non-Profits


A collage of cosmic images includes colorful nebulae, galaxy clusters, planets, and stars.
Text, News from the universe.
An image of the sun in green and red coloring, showing solar flares and a haze around its edges.
Text, February 17, 2023. Hints of solar nanoflares. X-ray and ultraviolet light.
Why is the sun's outer atmosphere, the corona, 100 times hotter than its surface?
It's one of the biggest mysteries in solar science.
It's as if the air around a fire were 100 times hotter than the flames.
NASA's NuSTAR mission is helping to find answers by observing high-energy X-rays emitted by the hottest material in the corona.
The image of the sun fades away into a spherical grid. There are blue splotches indicating areas on the sun diagram.
Text, The high-energy X-rays appear at only a few locations.
These sites may be where clusters of eruptions called nanoflares have occurred in the corona, superheating its material.
The green and red colored image of the sun replaces the grid.
Text, Continued study will show if nanoflares occur often enough to cause the corona's million-plus degree temperature.
This news was brought to you in part by the Jet Propulsion Laboratory in Pasadena, California.