Earth's Shadow, Paranal

Paula Santos pictured the Earth's shadow and Belt of Venus rising behind two of the auxiliary telescopes of the Very Large Telescope Interferometer at the European Southern Observatory, Paranal, Chile.   ©Paula Santos
Image © European Southern Observatory
Antu, Kueyen, Melipal and Yepun. The four 8.2m telescopes of the Paranal, European Southern Observatory in the Atacama desert, Chile. In front of them are the four smaller (1.8m) auxiliary telescopes. Three have their domes open.

All the telescopes are optically linkable via underground tunnels to form an interferometer array (VLTI) to give increased sensitivity and very high angular resolution.

The four auxiliary telescopes can move on tracks to give a flexible interferometer configuration. They can also act as an interferometer independent of the 8.2m telescopes.

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After sunset a dark purple hued band rises along the eastern horizon - the shadow of the Earth. Its upper edge is often suffused with a rosy pink glow - the Belt of Venus or Anti-twilight Arch.

The shadow is three dimensional and marks the unlit atmosphere masked from the sun's rays by the Earth's rim.

The upper edge of the shadow is where the sun is just setting and there its rays are most reddened by Rayleigh scattering. The reddened rays combine with scattered blue light from the atmosphere to give the pinks of the Belt of Venus.