At 2,500m up in the northern Atacama desert in Chile, Paranal is no place for human beings to live for long periods: dry, dusty and almost lifeless. But it is perfect for watching the skies. At night, the bone dry air means the Very Large Telescope (VLT) can track and measure stars, black holes and planets with exquisite precision using its four individual observatories.
In this podcast Alok Jha describes his visit to the Atacama Large Millimetre/Submillimetre Array (Alma) which is also now taking shape in the desert. When complete in 2013, this collection of 66 carbon-fibre radio antennae, each 12m wide, will open astronomers' eyes to the half of the universe that has, until now, been hidden to modern optical telescopes.
Alma will detect radiation similar to microwaves, around 1,000 times longer than the light we see with our eyes – but easily absorbed by water in the atmosphere.
The music for the show was composed by Iain Chambers.
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