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.




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               Mystery 1 : Waves in the Sky


TWAN Solve a Mystery

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What is the wave-like structure in this photograph besides the Milky Way as seen from a remote location in northern Chile? Did TWAN photographer capture a UFO, a squadron of hidden alien spaceships?!
More about the photo: viewing the sky from very high altitude locations is an amazing experience. Stars become sharp and dazzling with less atmospheric turbulence and extinction affected on their light. Located in Lauca National Park at Chile's far north on the border with Bolivia, volcanoes Pomerape (6282 m) and Parinacota (6332 m) are captured under the Milky Way in April 2010 by TWAN photographer Stephane Guisard from 5000m high in Chilean Andes. The photo is made with a single 20-second exposure using a DSLR camera (at high ISO) and 35mm lens. See more TWAN photos of Lauca National Park.

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





Karim Baba-kishi

I think the luminescent green colour appears to be present across a wide expanse in the sky. It also appears to be reflected off the surface of the “wavy” structure. The green itself may be associated with particles, which originate from the Sun, colliding with the magnetic field of the earth; they are probably a form of weak Borealis. As for the waves, I think they are ultra-high-altitude Noctilucent clouds, which are interacting with the gravitational field of the Earth in such a way as to cause the clouds to oscillate. Such regularly spaced wavy behaviour may also be seen in normal clouds of certain structure, altitude and thickness. Assuming the wave-like structure is caused by the earth’s gravity, such waves may provide a way of investigating the characteristic properties if gravitation itself.


Gravity waves

Till Credner

Hi, nice idea with this mysteries. I agree with the airglow due to the typical green and red color. However, I am not sure with the atmospherical gravity waves. It also could be fringing in the optics or the filter in front of the chip. Airglow is monochromatic light and therefore easily gives interference patterns in thin films like the anti aliasing filter or the infrared cutoff filter of the camera. Stephane, just make a test with diffused laser light on a white wall and picture this. You might again get such interferometric fringes!


Conclusion: with special thanks to all the posted answers, the current best explanation for the recorded phenomena seems to be "airglow" and atmospheric gravity waves.

John Bj

thin, high altitude clouds provide the slight distortion

Babak Tafreshi

Here is another TWAN photo by Doug Zubenel with similar wave-like forms (which is explained as airglow), taken three years ago in the US:

Babak Tafreshi

Just a note that the term Atmospheric Gravity Waves is a geophysical term, a totally different phenomena from the cosmological Gravitational Waves (which is yet to detect). Here is a good video of Atmospheric Gravity Waves in action by Jerry Lodriguss: And very good information here:

Babak Tafreshi

Very interesting comment by Dr. David Malin about the possible connection of the recorded atmospheric phenomena and the recent Iceland volcanic eruption.

David M Scott

As with the Milky Way in the undisturbed night sky, the every changing space interim shows effects of these changes.

Lloyd Moore

Looks like a pre-dawn photo looking North-easterly from near the coastal low country. The lightened streaks on the right-hand side of photo possibly caused by the "pre-dawn sun east of the Chilean Andes.

David Malin

The red colour gradually increases in intensity towards the horizon, so I'd suggest this is a very high altitude layer of tenuous dust reflecting the sunset (or sunrise) colours from a very distant horizon. This could possibly be traces of dust from the Eyjafjallajökull volcano in Iceland. A similar thing happened after the much more violent outburst of Mt Pinatubo in 1991. After 18 months the sky was still visibly red several hours after sunset, and was likely detectably red for much longer -- see While what I saw had a gradual gradient, there is sure to be wave-like turbulence at high altitude and here it is emphasised by the low angle of the red glow from the distant horizon, off to the left of the photograph. If anyone has detected gravitationl waves photographically (or in any other way) the Nobel Prize is theirs!


The waves should be stellar dust which reflects and scatters light from the cosmos.

Julio Vannini

That looks like a jet contrail... spaced and expanded after some period of time...

Sean Walker

My guess is the same, ultra-high material that manifests itself as Noctilucent clouds when illuminated in a different way.

S. Schräbler, Germany

This looks like an interference from a filter in front of the camera. The Filter may build some kind of Fabry-Perot-Etalon. The travel in the etalon will change with the image angle and we see multiple maxima and minima. What bothers me is that the structure is linear and not circular, so there is a second explanation, lets keep the filter, but let the effect be different: Perhaps Stephane left his polarizing Filter in front of the camera to reduce reflections from Laguna Verde as they appeared hours before in the sunset while he wanted to take a time lapse movie. If it is really something out there in the Atmosphere it must be polarizing the light. The colors in the structure bring me to this conclusion. Perhaps there are some ice crystals, but those are very seldom next to Cerro Licancabur in 5000m MSL and above. It is one of the driest high deserts out there, however there are some geysirs north of this locaction in El Tatio. This could be the source of water.


Just to note airglow originates in the Earth atmosphere while the counter glow (Gegenschein) and the zodiacal light are originated in outer space, by sunlight reflecting from dust in the solar system disc.

Ali Abedi

Surely this an amazing Night time AIR GLOW. This phenomenon was first identified by Anders Ångström. You can find some more information about air glow in this link (wikipedia): And a very amazing image here (of course about counter glow):


Not UFO, or thin cloud - Mr. Zamani and Mr. Eirexas are correct. This is a display of upper atmospheric airglow, some of which in this case is banded due to Earth gravity waves. Like auroral displays, stars can be clealy seen through airglow - high clouds will cause slight to moderate diffusion of the star images (at least in photos, if not visually). Because of the human eye's sensitivity green light, red airglow is invisible to the naked eye, but shows well in photos. See Also see


Not UFO, or thin cloud - Mr. Zamani and Mr. Eirexas are correct. This is a display of upper atmospheric airglow, some of which in this case is banded due to Earth gravity waves. See


I hope it would be UFO! :D

F. Eirexas, Spain

Airglow. Explanation and photos at:

Mohammad Saber Ali Aghaei

I agree with Pete Raine, they are thin clouds.

Mahdi Zamani

A global high atmospheric phenomena that named: Airglow. This phenomena usually has seen at dark nights, between 10&40 degrees above the horizon. In fact it's an atmosphere glow in near infrared waves. upper locations like mountains help you for seeing this event easily.

Pete Raine

Thin cloud


The cosmos is a giant shark and these are its gills. It inhales cosmic dust and spits out stars. ;) Sorry, Babak, I couldn't resist the temptation to have a little fun here. I wanted to give this 'Solve a Mystery' feature a try.


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