The Sky of the Earth by Serge Brunier

2009 September 11: This is our cosmic world, the sky of the Earth which has amazed humanity for ages. The vault of heaven, which envelops us in a dark velvet sphere spotted with stars, is seen here projected onto a plane. The Milky Way is the most imposing view in this sky representation; an island of over 150 billion stars. Less than 0.0001% of these are visible here. The all-sky image place us in front of our Galaxy, as we were looking from outside. It gives viewers the cosmic landscape in which our little blue planet is immersed. The general aspect of our spiral galaxy, with its thin disc, harboring young stars and marbled with dark or bright nebulae, its central bulge, and its satellite galaxies, are all easily recognized. Meanwhile it shows the sky that relates to everyone with constellations and their prominent figures whose names have nourished all childhoods, its myths and stories shared by all civilizations. The image was therefore made as man sees it, and records it with a regular digital camera.

In the framework of the International Year of Astronomy 2009, and in collaboration with the European Southern Observatory (ESO), this improbable 360-degree panoramic image was photographed by Serge Brunier mainly from the European observatory sites under the pristine sky of Atacama Desert of Chile (in the southern hemisphere) and La Palma obseravtory in the Canary Islands (in the northern hemisphere). The all-sky image is in fact a mosaic composed of almost 300 fields, each captured four times, for a total of 1200 photos. All were taken with a Nikon D3 digital camera and a 50 mm lens at f5.6. Each image is the result of a 6-minute exposure. The apparent motion of the sky, caused by Earth’s rotation, was corrected using a small equatorial tracking mount.

As noted by the photographer and astronomy writer “I started imaging in summer 2008 in Chile from the La Silla Observatory, and then from the Cerro Paranal Observatory, home to the most famous Very Large Telescope array. In addition to pristine skies, in the Atacama Desert I had the opportunity to enjoy exceptional meteorological conditions, as the sky is clear almost eleven months per year.”

Brunier continues how the planets and other moving objects are removed or faded in the background sky “While photographing, in between the northern summers of 2008 and 2009, solar system objects invited themselves into the stars’ infinite ground: blinding planets Venus, Jupiter and Saturn, as well as the more discrete and farther Uranus and Neptune, and even a comet with emerald green brilliance. They all lost among tens of millions of stars, and that you will have difficulties finding. The Sun and the Moon are of course missing in the picture as the fields have been photographed in best time to avoid any affect of the Sun or the Moon.”

After Chile the effort continues in the other hemisphere. As told by Brunier “Once I had photographed the whole visible sky of Atacama Desert, from 90 °S till 40 °N, a small region of the sky, around the Polar Star, was scanned from the Alpes-de-Haute-Provence, in France. I was located not far away from the little town of Castellane, on isolated peaks about 1500 to 2000 m high, and far from light pollution. Finally, the remaining northern hemisphere was photographed from the Roque de los Muchachos, in the Canary Islands. On top of the Caldeira de Taburiente, 2400 m above sea level, the observatory emerges from the sea of clouds that covers the hillsides of the La Palma Island. I lived in this way for almost thirty nights, in complete osmosis with my camera and the sky, and heard about 1200 times the “bip bip” announcing the next exposure. And finally the total exposure time of this image reached close to 120 hours.”

Meanwhile, in near Paris, the photographer’s computer expert team-mate, Frederic Tapissier, looked for technical solutions to the stitching of these hundreds of celestial fields, a total of 15,000 million pixels or about 20 GB of data. As noted by Brunier “Frederic and his computer spent more time and sleepless nights to process the data than my Nikon spent recording them. Frederic found the solution by choosing the new image processing software Autopano Pro Giga, which enabled the computation of the full representation of the heaven vault projected onto a plane after only 340 CPU work hours! The intermediate produced file was 145 GB large. The final image contains 40,000 x 20,000 pixels or 800 million pixels. It is 4.42 GB in size and is coded over 48 bits, representing more than 200 million millions of colors.”

With the picture of the whole sky taking shape, the European Southern Observatory became more involved with the final success of this project. Astronomer Henri Boffin shared an idea to further complete this endeavor, by asking Stephane Guisard, and astrophotographer and TWAN member on Cerro Paranal, to zoom into the centre of the Milky Way with a powerful hobby telescope and a CCD camera. The 2.2-meter telescope at ESO’s La Silla Observatory equipped with a wide field camera; was also used for several nights to produce a further zoom into the image of Stephane Guisard. The result is the most breathtaking dive ever made into our Galaxy.

The cosmic wallpaper image has already received a wide media exposure through French TV and most popular newspapers such as Liberation and Le Monde. From late August to mid-September, this entire sky view was exposed in a 12 meter long print in the « Un ciel pour une planète » exhibition, in the Atrium of the Monte-Carlo Casino, in Monaco.

Read the complete report and details by Serge Brunier on the production of this image.
See the European Southern Observatory press release on the 360-degree entire sky image with access to high-resolution images and videos.
Zoom in and learn about interesting sections of the entire sky image in the website of GigaGalaxy Zoom project.


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