Solve a mystery

TWAN brings you photos with mysteries. Share your thoughts with us and our global viewers. While some of the photos display a real mystery of unidentified object or phenomena, some others are already solved by TWAN team and appear here for educational purposes. TWAN post the explanation or the final conclusion at the month’s end. This program is a collaboration with Unidentified Aerospace Phenomena (UAP) international project.




Solve a mystery




Mystery 3

Streaks in Orion


Mystery 2

Mysterious Cloud


Mystery 1

Waves in the Sky



All mysteries



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               Mystery 4 : Dark Bands in the Sky


TWAN Solve a Mystery

What are the dark vertical bands on the right side of this image above prominent stars of Taurus (including Pleiades) and through the constellation Perseus? In a September night of 2010 TWAN photographer Yuichi Takasaka was near the town of Yellowknife in the Northwest Territories of Canada. The town is known as one of the world's best urban locations to see aurora or northern lights. An active aurora display is captured on the left (north east) while there are parallel and strangely aligned vertical dark bands on the right (east) between weaker aurora rays. In a panoramic image of the view the photographer has noticed the faint lines also 180 degrees away, at the opposite direction above the western horizon. The images were taken at about 2:30 am local time on September 19. The moon was about to set (at 2:40) and sunrise was about 5 hours later. Do these lines represent a rare kind of black aurora (also known as anti aurora); a phenomena which is well recorded in many aurora images? Are they digital noise by the camera? Or do they display an atmospheric phenomenon related to the setting moon or shadows in the aurora lights made in the lower atmosphere? Yuichi Takasaka has been photographing aurora for 20 years and this is the first time he has seen these vertical lines in his images. See TWAN special Aurora Gallery. More about dark aurora on NASA's APOD and here. More about various atmospheric phenomena on the Atmospheric Optics.

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(All answers will be reviewed by TWAN before it is posted)





Steven Christenson

I have seen similar rays after sunset in the Sierra Nevada Mountains. The cause was clearly shadows from mountain peaks. Here My guess is that there is enough particulate (cloud/moisture) in the air that a local bright light source is illuminating the clouds and the dark lanes are blocked by nearby trees. If this location is at elevation, that light source might very well be the moon and the trees seen in this picture are the trees in question. Anything in the opposite direction would have a similar cause.


I guess it's a classical airglow caused by gravity waves


The clouds blocking out the glow from the aurora.

David Thorman

I believe the effect is due to being directly in line with the Earths magnetic field lines at the altitude the ionization is taking place.

LeRoy Zimmerman

If you really look at the image there are no dark bands. The 'dark' bands are not dark, they are the same color as the night sky. The appropriate question would be 'what are the light bands?'. The light bands appear to be aurora. Why the aurora is generating that pattern would seem to be the real mystery.


Since the with seems to be the same over the whole length and the line is quite staight. This suggests to me an artifical (man made) source. For me it looks like a contrail of a plane.

Thad V'Soske

There may be a similar phenomenon going on in this TWAN Guest Gallery image:

hooman zamani

i don't see "dark" bands!! i think sky through those bands are just more clear. sky in other parts is a little green. i see pleiades alittle green, but in bands sky is blue. perhaps the bands are some kind of gap in aurora...

Herbert Raab

First, I though that these might be anticrepuscular rays induced by the setting moon (and the fainter lines 180° away would be crepuscular rays). But, if I have done my homework right, the moon was setting in the southwest, and anticrepuscular rays would thus converge towards the northeast (outside the field of view to the left), in the opposite direction of the setting moon. A quick look at the complete panoramic image could settle that question.


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