The Photopic Sky Survey: The Entire Night Sky

[Serena Duvet]

THE WHOLE NIGHT SKY

Nick Risinger has always gazed up at the sky. But last year the amateur astronomer and photographer quit his day job as a Seattle marketing director and lugged six synchronized cameras about 60,000 miles to capture an image of the entire night sky.

Mr. Risinger, 28, set up his rack of cameras in high-elevation locales in the Western U.S. and South Africa, timing photo shoots around new moons when nights were long and dark. He programmed his six cameras to track the stars as they moved across the sky and simultaneously snapped thousands of photos.

He then stitched 37,440 exposures together into a spectacular, panoramic survey sky that he posted online two weeks ago. The photo reveals a 360-degree view of the Milky Way, planets and stars in their true natural colors. Viewers can zoom in on portions of the 5,000-megapixel image to find Orion or the Large Magellanic Cloud.

"I wanted to share what I thought was possible," said Mr. Risinger, a first-time astrophotographer. "We don't see it like this. This is much brighter. On a good night in Seattle, you'll see 20 or 30 stars. This, in its full size, you'll see 20 to 30 million. Everything is amplified."

Other sky surveys have preceded this one, including the Digitized Sky Survey, a source for Google Sky. Many serve scientific purposes and were shot in red and blue to measure the temperature of stars, Mr. Risinger said. He shot in a third color, green, to give the photo added depth and richness, he said.

"This is not a scientifically useful image. This is for educational and artistic appreciation," Mr. Risinger said, adding that he wasn't motivated by money but hopes to sell prints and other products to keep the website running.

To capture the entire night sky in a year, Mr. Risinger plotted out an exact schedule of images he needed from both hemispheres. He divided the sky into 624 uniform sections and entered the coordinates into the computer.

"The sheer amount of work was mind-boggling," he said at his apartment in Seattle. "It's not a wing-it kind of project."

In March of last year, Mr. Risinger and his older brother, Erik, traveled to the desert near Tonapah, Nev., and took the first photos of what eventually would become his Photopic Sky Survey. He later also persuaded his retired father, Tom, who lives in Gig Harbor, Wash., to join him.

Above article BY PHUONG LE, ASSOCIATED PRESS, May 14, 2011

ONLINE: http://skysurvey.org

[Jitendra Hy-do-u-no-us?]

Thanks Serena hope to walk with u and watch the stars. Have u been to the Griffith Observatory lately?

Jitendra

[Jitendra Hy-do-u-no-us?]

Last nite i observed Saturn and Spica which can be seen in the constellation Virgo. It is hard to believe that it actually has an apparent brightness that is over 1900 times the brightness of our own Sun and rotates around a dual star. It is in the Southeast sky.

Jitendra

SPICA (Alpha Virginis). Spica, the luminary of Virgo, becomes prominent in the southeast in northern spring evenings, and can easily be found by following the curve of the Big Dipper's handle through Arcturus and then on down. Though a large constellation, Virgo, the Virgin, does not have much of any prominent stellar pattern, relying on Spica to tell us where it is. The star lies about 10 degrees south of the celestial equator, and practically on the ecliptic, the path of the Sun, and is regularly occulted, or covered over, by the Moon. The Sun passes Spica in the fall, rendering the star a harvest symbol that is reflected in its name, from Latin meaning "ear of wheat," the name actually going back to much more ancient times. Though at a distance of 250 light years (second Hipparcos reduction), Spica is still first magnitude (1.04), showing its absolute brilliance, the star visually 1900 times more luminous than the Sun. The apparent brightness is deceptive, however, as Spica actually consists of two stars very close together (a mere 0.12 Astronomical Units apart) that orbit each other in slightly elliptical paths with a period of only 4.0145 four days, which makes them difficult to study individually. Both are blue class B (B1 and B4) hydrogen-fusing dwarfs (the brighter nearing the end of its stable lifetime), making Spica one of the hottest of the first magnitude stars. The high temperature produces a great deal of radiation in the ultraviolet, which renders Spica vastly brighter than visually indicated. The brighter primary star has a temperature 22,400 Kelvin, a true luminosity of 12,100 Suns (after taking ultraviolet radiation into account), a radius 7 solar, (25 percent the separation between the two stars) and a mass 10.5 times solar, which may be enough to send it someday into a supernova explosion. The more poorly-known respective parameters for the secondary cooler star are 18,500 Kelvin, 1500 solar luminosities, almost 4 solar radii, and just 6 solar masses. Spica exhibits subtle brightness variations that were once thought to be caused by a grazing eclipse, each star slightly cutting off the light of the other each orbital period. The variation of 0.03 magnitudes is instead actually caused by the fact that the stars tidally distort each other and are not quite spherical, so as they orbit they present changing apparent diameters to the observer. The primary star is also a pulsating Beta Cephei (or Beta Canis Majoris) variable, which superimposes another variation of 0.015 magnitudes with a much shorter period of 0.17 days. The star is a strong source of X- rays, at least some of which seem to be produced when the winds that flow from the companions violently collide. Lunar occultaions yeild evidence that Spica is in fact multiple, with three other fainter components.
Written by Jim Kaler. Return to STARS.