Weather in Space

Sunspots and Solar Activity

How big do sunspots get?

Sunspots can range from the relatively small and, except with a telescope, unobservable, to the staggeringly enormous. The biggest sunspots can be more than 100,000 miles (161,000 kilometers) across. Astronomers measure sunspots in “millionths,” with each millionth being one millionth of the surface area of the Sun that is facing the Earth. The Earth, if it were a sunspot on the surface of the Sun, would be equal to 169 millionths. Compare that with the typical sunspot, which ranges from 300 to 500 millionths, and you get an idea of how big they are. One of the largest sunspots ever measured was seen in 2001 and was 2,400 millionths. But that does not account for how far the solar flares emanating from sunspots shoot out into space; solar flares can be as long as 100,000 miles (161 thousand kilometers), and some of the energy they emit can literally stretch to Earth’s orbit, 93 million miles (150 million kilometers) away.


This is a web preview of the "The Handy Weather Answer Book" app. Many features only work on your mobile device. If you like what you see, we hope you will consider buying. Get the App