On August 1, astrophotographer Bart Declercq went outside to get some shots of our nearest star. He used a 30 centimeter (12") telescope, two filters, and a pretty nice camera, he took several thousand frames of video of the Sun. Using a technique that allows combining the frames to get the highest resolution image - and then using a further technique called deconvolution to sharpen it a bit more - he was able to create this tremendous picture of a sunspot:
[Click to ensolarnate and get the 3000 x 2000 pixel hi-res version; this picture displayed here is only one part of a much larger image!]
Wow! This sunspot is officially called Active Region 1532, and is still visible on the Sun's surface. The detail you can see here is amazing; the spot's umbra (the dark region) is obvious enough, but the amount of small-scale features in the penumbra (the lighter outer region) is incredible. Surrounding the spot are granules; the pebbly-looking structures which are actually huge convection cells on the Sun. Hot plasma (gas where its atoms are stripped of one or more electrons) from inside the Sun rises to the surface, cools, and sinks back down. Granules are the tops of these convection cells.
Sunspots are where the Sun's fiercely complex magnetic field breaks through the surface, looping outward and back down, beginning and ending in the spots. These loops of magnetism tend to suppress convection. The plasma cools but cannot sink down. The brightness with which the plasma glows depends on its temperature, so the cooler plasma in the spot appears dark against the hotter material around it.
The scale of all this is hard to grasp. A quick measurement on the image indicates that the spot is about 20,000 kilometers (12,000 miles) across... in other words, just the spot's umbra alone is roughly the same size as the Earth!
It's easy to forget just how mighty the Sun is, but pictures like this really slam it home. The Sun is a star, 1.4 million kilometers across, 330,000 times as massive as the Earth, and a complex, amazing, and wondrous place.
Image credit: Bart Declercq