The Milky Way Panorama

The first of three images unveiled for ESO’s GIGAGALAXY ZOOM project is a magnificent, 800-million-pixel, 360-degree panoramic image that covers the entire southern and northern celestial sphere and reveals the cosmic landscape surrounding our tiny blue planet.

The plane of our Milky Way Galaxy, which we see edge-on from our perspective on Earth, cuts a luminous swath across the image. The coordinates provided in GIGAGALAXY ZOOM place the viewer in front of the Galactic Centre with the Galactic Plane running horizontally through the image — almost as if we were looking at the Milky Way from the outside. From this vantage point, the general components of our spiral galaxy come clearly into view, including its disc marbled with both dark and glowing nebulae, which harbours bright, young stars, as well as the Galaxy’s central bulge and its nearby, irregular galaxies.

As filming extended over several months, objects from the Solar System came and went through the star fields, with bright planets such as Venus, Jupiter and Saturn, as well as the more distant and discrete Uranus and Neptune, all making appearances. A brilliant, emerald-green comet also flew by, although spotting it among a background of tens of millions of stars will be difficult (and rewarding).

The painstaking production of this image came about as a collaboration between the renowned French writer and astrophotographer Serge Brunier, his fellow Frenchman Frédéric Tapissier, and ESO staff. Brunier spent several weeks during the period between August 2008 and February 2009 capturing the sky, mostly from ESO observatories at La Silla and Paranal in Chile. In order to cover the full Milky Way, Brunier also made a weeklong trip to La Palma, one of the Canary Islands, to photograph the northern skies.

During his quest, Brunier used a Nikon D3 digital camera and a 50 mm lens. The apparent motion of the sky caused by Earth’s rotation was corrected for using a small, precise equatorial mount moving in the opposite direction. Each photo required a six-minute exposure, for a total exposure time of more than 120 hours.

Once the raw photographs were in hand, image processing by Tapissier helped to accurately convey the night sky as our eyes behold it. The data processing, using software called Autopano Pro Giga, took great care in respecting the colours and “texture” of the Milky Way. Tapissier needed about 340 computing hours on a powerful PC to complete the task. The resulting image was carefully balanced in a way that faithfully represents the sky with the unaided eye from a very dark site. The subtle colours and soft contrasts may be less dramatic than those of other images of the Milky Way, but they convey the experience of a nigh at Paranal.

The resulting image now available on GIGAGALAZY ZOOM is composed of almost 300 fields each individually captured by Brunier four times, adding up to nearly 1200 photos that encompass the entire night sky.