Many sunspots are as big as the Earth's area, and large ones can be 10 times or even up to almost 50 times as large as the Earth. I'm not sure which one is the largest so far, but this website has some interesting information about some notably large sunspots: www.spaceweather.com/sunspots/history.html

And sunspots are grouped together in "active regions," which are regions that have very complicated magnetic fields. These sunspot groups are the places where most solar flares come from!

Howdy, Liz;

Indeed, it's essentially how much total magnetic flux -- field strength times area -- that gathers together to make a sunspot bigger. And, although I do hate to sound like an old geezer, this solar cycle maximum that we're in now has been notable in the lack of really big sunspots. Still, if you can look at the images of today's Solar disk (see, e.g., spaceweather.com, which is a very nice site...), there's a fairly respectable-sized sunspot rotating into view. Take a look on the website. If you have binoculars or similar, and use the projection method (do NOT look directly at the Sun or look through binoculars at the Sun!!!), this big sunspot will be easily visible.

have fun, -KD