On February 11, 2010, as NASA’s Solar Dynamics Observatory (SDO) was launched into space, its path took it directly through an atmospheric optical phenomenon known as a sundog. In the video above, you can hear observers gasping in surprise as the rainbow-colored sundog disappears as the spacecraft passes through that part of the atmosphere. It was an auspicious start for a spaceship that helped us understand our local star. And the launch also brought to light a new form of ice halo and taught those who love and study the optics of the sky new perspectives on how shock waves interact with clouds.
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A sundog is a bright rainbow-colored spot in the sky, formed by the refraction of sunlight through plate-shaped ice crystals that go down from the sky like leaves fluttering from trees. Les Cowley of Atmospheric Optics explained what happens in the video to a post at Science @ NASA:
When the rocket penetrated the cirrus, the shock waves penetrated the cloud and destroyed the alignment of the ice crystals. This extinguished the sundog.
In this simulation, the sun is surrounded by a 22-degree halo and flanked by solar dogs. Read more at Les Cowley’s Atmospheric Optics.
In the video, watch closely the bright column of white light that appears next to the Atlas V rocket that fueled the 2011 SDO launch. Although Cowley and other sky optics experts understood why the sundog disappeared, they did not understand the events that followed. , especially that column with white light. Cowley said:
A bright column of white light appeared near Atlas V and followed the rocket into the sky. I had never seen anything like it.
Larger view. | When the Dynamic Solar Observatory (bright stripe in the lower left quadrant of the photo) left Cape Canaveral on February 11, 2010, its launch allowed opticians to discover a new form of ice halo. Image by NASA / Goddard / Anne Koslosky.
Cowley and colleague Robert Greenler at first could not explain this column of light. Then they realized that the plate-shaped ice crystals were organized by the shock wave from Atlas V. Cowley explained:
The crystals are tilted between 8 and 12 degrees. They are then rotated so that the axis of the main crystal describes a conical motion. The toy charts and the gyroscope do it. The earth does it once every 26,000 years. The movement is orderly and precise.
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By the way, NASA’s Solar Dynamics Observatory has been observing the sun for 11 years now. It is one of the many observatories that monitor our sun, part of NASA’s Living with a Star program. The video below highlights some of SDO’s accomplishments over the past decade.
Conclusion: On February 11, 2010, a space observatory launched into space broke a sundog and created a new halo of ice that amazed scientists.
Via Science @ NASA
Via Cowley’s Atmospheric Optics
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