A Nasa satellite designed to uncover hidden cosmic objects has been blasted off from California.

The Wide-field Infrared Survey Explorer blasted off from Vandenberg Air Force Base on a Delta II rocket just after 1409 GMT.

It will pick up the glow of hundreds of millions of astronomical bodies.

The probe is expected to uncover objects that have never seen before, including some of the coolest stars and the most luminous galaxies.

It will do this by scanning the entire sky in infrared light with a sensitivity hundreds of times greater than ever before.

Viewing the sky with "infrared glasses" can lift a veil on many objects that are not visible to the naked eye.

Sky scanner

The satellite will also have a role in planetary protection: Wise will be able to detect some of the darkest near-Earth asteroids and comets.

This would help efforts to determine whether any of these objects could strike Earth in the near future.

Wise joins two other infrared missions in space: Nasa's Spitzer Space Telescope and the European Space Agency's Herschel Space Observatory.

This mission is different from those others in that it will survey the entire sky.

It is designed to cast a wide net to catch a variety of objects of interest.

Wise will target dim objects called brown dwarfs. These are effectively failed stars, having not gathered up enough mass to ignite.

Brown dwarfs are cool and faint, and nearly impossible to see in visible light. Mission scientists expect the spacecraft to uncover many hundreds.

This could double or triple the number of star-like objects known within 25 light-years of Earth.

The spacecraft will spend a month checking out its instruments.

The $320m project is managed by Nasa's Jet Propulsion Laboratory in California.