Best Solar Images - Part 2

Inverted Filaments

My solar imaging activities are coming to an end. I've spent 15 years happily watching the ever-changing solar chromosphere and capturing images with my solar telescope. Now is a good time to look back at some highlights and gather my best images together in one place. In this second post I'll present images that portray the floating cloud-like character of solar filaments. In three upcoming posts I'll present other examples of solar features and action.  

All images presented here were made with a Lunt 100mm single-stacked hydrogen-alpha solar telescope. Each image will indicate the camera and Barlow lens used. Often, single image fields of view were combined to include larger portions of the Sun. These separate panels were later stitched together into a single combined image using Photoshop.

The Sun's color seen by eye through the Lunt telescope's eyepiece is not yellow but rather a deep hydrogen-alpha red. The cameras I used are monochromatic cameras which produce only black and white images. I have arbitrarily added color to the original grayscale images below. These added colors have no physical significance. I merely liked them better than grayscale.

Finally, these images are best viewed at full size on a monitor, laptop screen, or projected on a TV. Smart phone viewing is a disappointing experience. Click on the images to get the full-size version. 

Many solar images include narrow dark shapes called filaments scattered around the Sun. These are regions of relatively cooler plasma suspended above the hotter chromosphere by magnetic fields. Filaments appear dark against the background because they are cooler than the background. When ordinary solar images are inverted positive to negative, the dark filaments appear as bright white clouds floating above the chromosphere. Image inversion highlights the cloud-like nature of filaments.

For example, consider the first image pair below from April 7, 2012. The upper image with dark sinuous filaments is a normal positive image with arbitrary color added. The lower image (shown in a different color) is the inversion of the upper one. White inverted filaments show a strong floating effect in the lower image. The positive image is a 9-panel mosaic made with a DMK41AU02.AS camera and a 2X Barlow lens. 

Another example comes from September 4, 2013. The upper positive image contains several dark filaments scattered across the disc. The lower inverted image, again in a different color, portrays these filaments as bright white clouds above the chromosphere below. Be sure to click on the images to view detail at full size. The positive image is a 9-panel mosaic made with a DMK41AU02.AS camera and 2X Barlow lens.

Three nearly parallel filaments appeared on the bottom right solar quadrant on March 21, 2014. The next positive image is a 26-panel mosaic made with a DMK41AU02.AS camera and 2X Barlow lens. The immediately following inverted image shows the three floating filament clouds, especially when viewed at full size.

On February 11, 2015, a spectacular long filament stretched almost entirely across the bottom of the Sun! I captured the 32-panel positive disc mosaic shown first below with a DMK41AU02.AS camera and 2X Barlow lens. The inverted image underneath reveals the long white filament cloud quite well. View at full size.

Filament inversion images were often quite striking when I used the DMK41 camera. After switching to a ZWO ASI174 camera, inversions never equaled their previous glory for some reason. Consequently, I made very few inverted images after 2015. The one exception was a 12-panel disc mosaic made with a 3X Barlow lens on July 12, 2022. The positive/inverted pair follows. View at full size.

My next post will feature solar prominences.