Space Weather 101
🔴 Sunspots
View live Sunspots data →What is Sunspots?
Sunspots are temporary dark patches on the Sun's visible surface, caused by concentrated magnetic field lines that locally suppress heat flow, making them appear cooler (and thus darker) than the surrounding surface — though they're still extremely hot in absolute terms. The sunspot number is a standardized monthly count of sunspots and sunspot groups, tracked continuously since the mid-1700s.
Why it matters
Sunspots mark active regions with tangled, energetic magnetic fields — exactly the regions that produce flares and CMEs. The sunspot number is used as a broad, months-to-years proxy for how active the Sun is likely to be overall.
Typical values
During solar minimum, monthly values can sit near 0 for extended stretches. During a strong solar maximum, they regularly exceed 100-150; Solar Cycle 25 (the current cycle) peaked in the 150-160 range around its maximum.
How scientists measure it
Observers count individual sunspots and sunspot groups visible on the Sun's disk (through properly filtered telescopes), then combine these counts using the standardized Wolf Sunspot Number formula: R = k(10g + s), where g is the number of groups and s is the total spot count.
Why it affects Earth
More sunspots generally means more solar activity overall — more flares, more CMEs, and a generally more "stormy" Sun — even though the sunspot number itself says nothing about any single event or day.
FAQ
Are sunspots dangerous?
Not directly — a sunspot itself is just a magnetically active surface feature. The danger comes from the flares and CMEs that active sunspot regions can produce.