The largest sunspot group of 2026

Sunspot group 14478 observed today (June 28, 2026) East of solar central meridian has a total area of 1190 Millionth of Solar Hemisphere (MSH). This makes it the largest sunspot group of this year. Attached image from GONG Learmonth station in Western Australia shows this group with two large sunspots on the left side of the solar disk. While this is a large sunspot group, it is not a record-breaking one. The largest sunspot group was observed in April 1947. The sunspot drawing from the Mount Wilson Observatory in California provides example of that monstrous sunspot group on 7 April 1947. The drawing is scaled to match the size of GONG image (circle corresponds to the same disk size as GONG). The area of that group was 7400 MSH, or about 6.2 times of AR14478. Sunspot group areas approximately scale as the total magnetic flux of an active region. Groups with larger areas have more potential for producing solar flares and coronal mass ejections. In comparison, in March 1989, an active region with the total area of 2400 MSH produced a very powerful flare and CME. The eruption caused one of the strongest geomagnetic storms, which resulted in a nine-hour outage of Hydro-Québec's electric transmission system in Canada. The Carrington event (1-2 September 1859) was associated with an active region of 2300 MSH in size. However, not all large sunspot groups produce strong eruptions. So far, AR14478 showed only a few moderate C-class flares.