The need for the SKA arises from astronomers desire to detect the faint emissions from hydrogen gas in structures formed soon after the Big Bang, and in the galaxies which developed from them. Radioastronomy has led to three of the five Nobel prizes awarded for work in astrophysics, including all those awarded for observational work. Radio telescopes have two big advantages over those operating at other wavelengths. First, they can see through cosmic dust. This dust often prevents optical telescopes from penetrating regions at the centres of galaxies where stars are forming.
Dust can even obscure entire galaxies at visible wavelengths.
The other advantage of radio telescopes is that separate telescopes can be combined into arrays, which act as very sensitive single telescopes, delivering the highest resolution images in astronomy. SKA s exceptional resolution will provide crucial new views, unaffected by obscuring dust, of the formation and early history of stars, galaxies and quasars. For the first time, an object detected by an other telescope can also be studied in the radio spectrum. SKA is therefore the perfect compliment to the next generation of large optical, infrared, and millimetre-wave telescopes. It will also play a major role in the search for extraterrestrial intelligence.