Yesterday, "amateur" astronomer César Cantú took an amazing mosaic image of the Sun, showing our star boiling and writhing under its own dynamic forces:
[Click to unGdwarfenate.]
That hardly looks like the Sun, does it? That’s because he used a filter that blocks all the light we see except for a very narrow slice of color in the red part of the spectrum. That filter lets through only light from warm hydrogen, at just the right temperature to allow the electrons in the hydrogen atoms to drop from the third energy level to the second. You can picture the electron in an atom like it’s on a staircase, and only allowed (by quantum mechanics) to sit on a step, or move from one to the other. It takes energy to move it up a step, and gives off energy when it moves down. When it jumps down from the third to the second, it emits a photon — a particle of light — at a wavelength of 656.3 nanometers, and astronomers call this light Hα (H alpha).
The gas on the Sun’s surface emitting Hα is under furious stirring due to magnetic fields and other forces, and you can see that in the twisted, roiling appearance in this photo. I particularly like the dark arc just left of center: that’s a filament, an eruption of gas off the surface. It’s about 150,000 kilometers (90,000 miles) long! It’s a bit cooler than the surface material, so it’s darker, and we see it in silhouette. When those happen on the limb of the Sun they’re called prominences, and you can see several of those in this picture too.
Amazingly, this picture (which is really a mosaic of six separate shots) was taken using a telescope with only a 90 mm (3.5 inch) lens. The Coronado 90 mm telescope is a favorite of sidewalk astronomers, since it shows the Sun in amazing detail, but is totally safe to look through since it blocks almost all the Sun’s light. It’s common to see them at planetaria and museums, set up where passers-by can get a quick glimpse of the Sun. For most, it’s the first time they ever see the might and power of a star only 150 million kilometers away.
And if you want a sense of scale here, in the picture above the Sun is about 450 pixels across. On the same scale, our entire planet Earth would be only about 4 pixels across.
Just in case you were feeling big and important today.
Credit: Image used by permission of César Cantú.