World’s biggest telescope array

How ALMA will give us our best view of the universe from Earth.


Each telescope uses interferometry to provide a clear view of the universe.

High in the Chilean Andes on the Chajnantor plain, 5,000m (16,400ft) above sea level, an array of radio telescopes known as the Atacama Large Millimeter Array (ALMA) is under construction, which will provide us with one of the clearest views of the universe yet. Once completed there will be 66 antennas trained at the sky, working in tandem with one another to observe the cosmos, the largest and most expensive ground-based telescope in history.

The truly remarkable aspect of this $1.3bn telescope group – a partnership between scientific teams across the world – is that a giant vehicle known as the ALMA Transporter can individually move each 12-metre wide antenna. This means the spread of the telescopes can range from just 150m to more than 11 miles (18km), providing varying levels of resolution to observe different parts of the universe. Once completed in 2013, ALMA will be ten times more powerful than the Hubble Space Telescope. Normally, ground-based telescopes cannot compare to space telescopes, the latter of which do not have their view obstructed by the Earth’s atmosphere. However, the huge scale of the ALMA array, coupled with its height above sea level where the atmosphere is thinner, will allow ground-based telescopes to match their space-faring brothers.

Image courtesy of ESO and José Francisco Salgado.

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