The Canary Island of La Palma is bidding to house the world’s largest solar telescope, a four-metre ground-based Advanced Technology Solar Telescope (ATST).
Since 1980, the island has been a solar research leader because of its excellent astronomical climate, and the proposed project would convert the island into the world centre on solar physical investigation.
‘We’re at the mercy of the Sun’, says Juri Toomre, an astrophysicist at the University of Colorado. ¨If the sun is magnetically active, it can blast holes in our communiciation systems. Or if the sun floods us with high-energy particles as flares go off, it will heat our atmosphere significantly. Our civilisation might be destroyed if the sun changes its output by one per cent either way.  You sure would like to know what’s operating this machine.¨ This is why constant research is essential to understand the sun’s activity.
As for La Palma, competition is tough, but Martínez Pillet, astrophysicist at the Canary Islands Astrophysical Institute, believes that the island is an excellent candidate for the project. The ideal daytime atmospheric conditions needed are frequently clear skies, excellent visibility, low humidity, few aircraft contrails and low dust levels, all characteristics of La Palma. Only sand storms from the Sahara could potentially affect atmospheric clarity.
Hawaii and the Big Bear solar observations are the main competitors for the project, yet their telescopes do not render as high image quality as do the La Palma telescopes.  However, the project will ultimately depend on sponsorship capabilities: the Hawaii and Big Bear telescopes are in United States territory whereas La Palma is Spanish, and the question is whether Spain and Europe are able to jointly fund the new project. 
Solar telescopes
In addition to the atmospheric effects, solar telescopes suffer from heating by sunlight of the optics and the air within the telescope. This causes the image to shiver and become blurred. Modern solar telescopes are either vacuum telescopes, filled with helium or use careful control of the optic's temperature to reduce heating of the air in the telescope. By filling the telescope with helium instead of air, the harmful effects of heat inside the telescope are greatly reduced although not as much as by vacuum. This avoids the large forces on vacuum windows but still requires an optical window of high quality but much smaller thickness than for a vacuum telescope.

Palma factfile

Geographical features
La Palma appears from space as a giant stone axe. The north of the island is dominated by the giant Caldera de Taburiente, from which the Cumbre Nueva and Cumbre Vieja ridges run due south to the sea. Like the rest of the Canary islands, La Palma is volcanic. There have been a number of eruptions in recent history, including the most recent volcanic eruption of Teneguia in 1971.
The most important geological feature of La Palma is the Caldera de Taburiente, which dominates the northern part of the island. This is a large depression, 5 km across, with an area of 30 sq km, and 2 km deep. It can be dated back to 2 million years ago, with the formation of a shield volcano some 20 km in diameter. However, the Caldera was formed not by the original volcanic activity, but by subsequent erosion. The result is one of the largest and most impressive erosion craters in the world.

Climate
La Palma lies in both the cool north-easterly Canary current and the north-easterly trade winds, giving it a sunny climate with year-round moderate temperatures, rather cooler than would be expected given the latitude of the island.