He’s still snapping away, and on August 17th took this lovely picture of a prominence erupting from the Sun’s surface:
[Click to enfilamentate.]
Isn’t that gorgeous? A prominence is a towering arc of material lifted off the Sun’s surface by intense magnetic fields. To give you an idea of how strong the magnetic forces are, a prominence can have a mass upwards of a hundred billion tons, and be cranked up thousands of kilometers off the Sun’s surface… despite the crushing gravity of nearly 30 times that of Earth’s!
And some people call the Sun "average". Ha!
Alan takes these images with a pretty nice ‘scope equipped with a filter that blocks all the light from the Sun except for a narrow slice of color preferentially emitted by warm hydrogen. He then inverts the image of the solar disk (but not anything on the limb or outside it), which is an old astronomy trick to make contrast more obvious to the eye.
This image is part of a much larger one showing much more of the solar edge, including another magnificent prominence. Amusingly (to me at least), when I saw the picture above, my first thought is that it looked like a sitting dragon, facing to the right, sniffing a fish floating in front of it (and given that I’m at Dragon*Con right now, I love this imagery even more). Then I realized it also looks like a dragon facing to the left, head down on the Sun’s edge, like it’s ready to pounce! I’d suggest staying out of its way; after all, this dragon would be about 150,000 km long: well over 10 times the size of the Earth.
Do you see it as a dragon too? Funny how once our minds latch onto a picture like that, it’s hard to not see it that way!