April 13, 2012 — Astrophotographer Alan Friedman captured this gorgeous portrait of the sun on April 7 from his home in Buffalo, NY, using a backyard solar telescope and a new Grasshopper CCD camera by Point Grey Research. Viewed in a wavelength emitted by hydrogen alpha (Ha) the sun's surface details become visible, showing the complex texture of our home star's true face.
Hydrogen is the most abundant element found on the sun. The sun's "surface" and the layer just above it — the photosphere and chromosphere, respectively — are regions where atomic hydrogen exists profusely in upper-state form, and it's these absorption layers that hydrogen alpha imaging reveals in detail.
The "furry" texture of the sun's surface is caused by structures called "spicules" — vertical tongues of superheated plasma that flare up from the photosphere. When observed inside the sun's disk, the darker horizontal structure of spicules are known as "fibrils." Plasma accelerated in spicules can travel vertically up to 55,000 mph and reach 3,000 miles (4,830 kilometers) in altitude before fizzling out — fibrils, on the other hand, appear somewhat less dynamic. There's an estimated 100,000 spicules distributed across the face of the sun at any one time.
The dark regions on the left hemisphere are solar flares surrounding active magnetic regions — a.k.a. sunspots, cooler zones where magnetic fields are welling up from deep within the sun. The rising fields prevent convection from taking place in those localized areas, which are often many times the size of Earth. Flares can occur around sunspots when magnetic fields snap, sending solar energy hurtling outwards.
Prominences can be seen leaping into the sun's atmosphere along the limb. Again, these are magnetically-formed structures that suspend solar plasma tens — sometimes hundreds! — of thousands of miles upwards.
See more photos by Alan on his blog here.
-- by Jason Major.