A Triumvirate: Three Coronal Holes
Three substantial coronal holes rotated across the face of the Sun this week.
Coronal holes are areas where the Sun’s magnetic field is open, acting as a source of streaming solar wind. The holes appear darker in extreme ultraviolet light because there is less material in the areas for this wavelength to image.
Coronal holes make frequent appearances on the Sun’s surface, and while it is a little unusual to have three coronal holes at the same time, it isn’t a rare occurrence.
Date: September 8–10, 2015
Instrument: Atmospheric Imaging Assembly (AIA)
Wavelength: 211 Å (Angstrom: a unit of length used primarily to measure light wavelengths. 1 Å is equal to 0.1 nanometer.)
Credit: Solar Dynamics Observatory/NASA
Solar Dynamics Observatory: sdo.gsfc.nasa.gov/
SDO's Atmospheric Imaging Assembly (AIA): aia.lmsal.com/