The infrared telescope, launched in August 2003, captured more than 300 newly formed stars, about 13,700 lightyears from Earth in a zone called RCW 49, in the Centaurus constellation.

Preliminary data show that the stars are surrounded by dusty discs, an early phase in a star's life, said Ed Churchwell, of University of Wisconsin in Madison, Wisconsin and the lead investigator of the RCW 49 research.

A star and its disc are located inside a dense envelope of gas and dust. Planets are born in a star's disc.

"By seeing what's behind the dust, Spitzer has shown us star and planet formation is a very active process in our galaxy," Churchwell said.

Michael Werner, the Spitzer project scientist at NASA's Jet Propulsion Laboratory in Pasadena, California, said scientists were only able to study a small sample of discs, but Spitzer will allow them to analyze thousands of them.

In another study, Spitzer was able to find ice particles within discs circling five young stars in the Taurus constellation, 420 lightyears from Earth.

The particles, covered with water, methanol and carbon dioxide, could explain the origins of comets, which many scientists consider the source of water and life on Earth.

One of the young stars shown by Spitzer, called CoKu Tau 4, could have in its orbit the youngest planet ever observed.

The star is about one million years old and the planet could be younger. By contrast, Earth is believed to be 4.5 billion years old.

"These early results show Spitzer will dramatically expand our understanding of how stars and planets form, which ultimately helps us understand our origins," Werner said.

In addition to Spitzer, NASA has three telescopes orbiting Earth: the Chandra X-ray Observatory, the Compton Gamma Ray Observatory and the Hubble Space Telescope.

A lightyear is the distance light travels in a year, about 9.5 trillion kilometers (six trillion miles).

SPACE.WIRE