Solar Observation - Blog Posts

A solar cycle: a montage of 10 years worth of x-ray images taken by the ようこう (Yōkō 'sunbeam') sun-observation satellite.

The Sun undergoes a cycle of magnetic activity with a period of about 11 years. At solar maximum, solar observatories see more sunspots on the Sun's surface. Solar flares and coronal mass ejections are bigger and more frequent, triggering auroræ in Earth's skies, interfering with some types of radio communication, and irradiating deep space hardware. The Sun's magnetic field also undergoes a polarity inversion during solar maximum, when the north and south magnetic poles on the Sun swap (this happens again 11 years later in the next maximum). By contrast, the solar minimum has very few or no sunspots and the Sun is generally calm; a good time for deep space missions.

The last solar maximum was in February 2014. The last minimum was December 2019, marking the transition from cycle 24 to 25 (records began in 1755). The next maximum is predicted for the second half of 2025.