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 …