Astounding Filament

Longest Filament Yet!

During five years of solar observation I've never seen a filament as long as the one recently spread across the Sun! This astounding cloud of hot plasma ran like a river: springing up near a sunspot and winding across almost an entire solar diameter on the bottom of the Sun! Here's a 32-image imperfect mosaic showing what it looked like on the afternoon of February 11th:

There were about ten filaments present including the enormous one. Only three modest sunspots added to the scene. The inverted version highlights the filaments.

The next two images are from NASA's orbiting Solar Dynamics Observatory. They were taken at about the same time as my images. My images show the solar chromosphere in the 6563-Angstrom visible red light of excited hydrogen atoms. The NASA images show the solar corona, above the chromosphere, in the 193-Angstrom extreme ultraviolet light of 11-times ionized iron atoms. The first image shows that the long giant filament also exists in the corona. The dark area in the center is a coronal hole where solar wind shoots out freely into space towards Earth.

The next NASA image shows magnetic field lines superimposed on the previous image. Whoa! You can see how the long filament runs underneath a tunnel of magnetic field loops. Amazing!

After my last observing session on February 4th I watched online daily as the huge filament gradually revealed itself. The full length eventually came into view as the Sun rotated for seven cloudy days. Finally, on February 11th, the afternoon sky cleared. The temperature was in the low 40's, normally a bit too uncomfortable for pleasant observing, but this unique feature lured me outside. The telescope mount functioned properly, and I captured images from 2:14pm EST to 3:25pm EST. Unfortunately, the seeing was not very good. Close examination of the first mosaic above shows slightly blurry sections. Details throughout are not as sharp as they normally are. That's why I reduced the mosaic from full size to one third size. It does no good to magnify imperfections.

This unusual filament is one of the most dramatic features I've ever seen on the Sun.