Rossby waves are a type of global-scale wave that develops in planetary atmospheres, driven by the planet’s rotation1. They propagate westward owing to the Coriolis force, and their characterization enables more precise forecasting of weather on Earth2,3. Despite the massive reservoir of rotational energy available in the Sun’s interior and decades of observational investigation, their solar analogue defies unambiguous identification4,
Coronal brightpoints (BPs) permit the tracking of the magnetic activity bands of the 22-year magnetic cycle of the Sun8. These activity bands in each solar hemisphere undergo significant quasi-annual instability, which results in episodes of intensified space weather6. The nature of the instability on the bands is unknown, but has been linked to the existence of magnetic Rossby waves in the solar interior5. We use our BP detection algorithm9 on a series of coronal images taken by the Extreme-Ultraviolet Imager (EUVI) instruments10 on the twin STEREO spacecraft, and by the Atmospheric Imaging Assembly (AIA) instrument11on the SDO spacecraft, in the 19.5- and 19.3-nm channels, respectively, from 1 June 2010 to 31 May 2013. During this time period, the orbits of these three spacecraft created an opportunity to explore global-scale solar phenomena. In concert, the trio of spacecraft provided the first complete observational coverage of the Sun’s corona, slowly drifting apart from the Sun–Earth line until STEREO-Behind lost communication with the Earth in mid-2014.