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GEMINI OBS/Canada-France-Hawaii Telescope
Stars twinkle because their light must pass through pockets of Earth's atmosphere that vary in temperature and density, and its all very turbulent. On rough nights, a star appears to constantly shift position as its light is refracted this way and that. The process has been likened to watching a coin appear to dance at the bottom of a pool.
With dense stellar clusters, the twinkling can make thousands of tightly packed stars look like one giant blob of light.
A handful of modern telescopes use a system of adaptive optics to overcome some of this turbulence. This new photo, released last week, is intended to show off the adaptive optics setup recently installed on the Frederick C. Gillett Gemini Telescope on Mauna Kea, Hawaii.
The star cluster, called M13, is well known to serious backyard stargazers. The whole cluster is seen in the yellowish image, made by the Canada-France-Hawaii Telescope, also on Mauna Kea.
The blue inset at the top-right is the detailed new view taken by Gemini. The other blue image, blurrier, is the same region seen by Gemini without its fancy new glasses on.
Adaptive optics gains clarity by adjusting a telescope's many segmented mirrors for atmospheric turbulence. The adjustments are made on the fly.
How good does it get?
"The resolution obtained in these images is approximately equivalent to seeing the separation between an automobile's headlights on the Golden Gate Bridge in San Francisco while standing 3,850 kilometers [2,392 miles] away in Hawaii," said Francois Rigaut, who helped developed the system.
M13, also called the Great Hercules Globular Cluster, contains more than 100,000 stars, most of them old. It is located about 23,000 light-years away and is one of many ancient star clusters in the Milky Way.
[Another Hawaii telescope uses a fake star]
-- Robert Roy Britt
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