V is for VLT

This Picture of the Week shows a huge celestial “V” emblazoned across the night sky over ESO’s Paranal Observatory, which is situated atop Cerro Paranal in Chile.

One arm of the “V” is noticeably clearer than the other; the right arm, pointing towards the top right corner of the frame, is traced out by the beautiful star-studded centre of the Milky Way. The fainter arm, leaning leftwards, is formed of glowing columns of diffuse zodiacal light, a phenomenon caused by incoming sunlight that is scattered by small particles of cosmic dust.

While we often see both the Milky Way and zodiacal light at Paranal thanks to the site’s famously clear skies, the “V” alignment shown here is unusual. Zodiacal light is related to the Earth’s path through space, as the dust particles responsible for scattering the sunlight are all within a cloud that lies on the ecliptic plane (dubbed the zodiacal cloud). Because of this, the glow varies in strength and visibility throughout the year, and is best seen in spring and autumn just after sunset or before sunrise. The opportunity to observe a beam of zodiacal light seeming to emanate from the very centre of the Milky Way comes only once per year, during January. For more information on this cosmic phenomenon, see ESOcast 82: Zodiacal light (esocast82a).

In the crook of the “V” sits one of ESO’s Very Large Telescope’s 1.8-metre Auxiliary Telescopes (ATs) — of which there are four in total. Each AT is housed in a robust enclosure that protects the delicate telescope and instrumentation from the harsh, arid desert conditions experienced at the site. Two other ATs are visible in the background towards the left side of the image.

The picture was taken by ESO Photo Ambassador Petr Horálek.