The Active Sun from SDO: HMI Magnetogram

The Helioseismic Magnetic Imager (HMI) aboard the Solar Dynamics Observatory takes a series of images every 45 seconds in a very narrow range of wavelengths in visible light of the solar photosphere. The wavelengths correspond to a region around the 6173 Ångstroms (617.3 nanometers) spectral line of neutral iron (Fe I). From this series of images, it constructs a set of images which extract other characteristics of the photosphere. For this dataset, it measures the splitting of the spectral lines to determine the intensity of the magnetic field on the solar surface. White represents north magnetic polarity and black represents south magnetic polarity.

This visualization is one of a set of visualizations (others linked below) covering the same time span of 17 hours over the full wavelength range of the mission. They are setup to play synchronously on a Hyperwall, or can be run individually.

The images are sampled every 36 seconds, 1/3 of the standard time-cadence for SDO. This visualization is useful for illustrating how different solar phenomena, such as sunspots and active regions, look very different in different wavelengths of light. These differences enable scientists to study them more completely, with an eventual goal of improving Space Weather forecasting.