London, Nov 14: Support for the theory of extraterrestrial life is gaining new ground after astrophysicists said that carbon-based molecules floating in interstellar space, might have been incorporated into Earth, thus providing the raw materials for life.

Astrophysicists believe that these organic molecules were present in the cloud of dust and gas from which our solar system formed.

Because of the fact that astronomers can see these molecules throughout our galaxy, they believe conditions may also be ripe for life in other parts of the Milky Way, and perhaps further afield.

So the hunt is on to find these molecules in other galaxies.

By looking at galaxies similar to our own, but at an earlier stage of their evolution, astronomers hope to work out how long these molecules have been abundant in the universe, and therefore how long the conditions suitable for life as we know it have prevailed.

The chemical signature of a class of organic compounds called polycyclic aromatic hydrocarbons can be seen in the way they absorb light from distant stars. The molecules are thought to leave a complex pattern of dark bands in these spectra called diffuse interstellar bands (DIBs).

In 2004, astronomers found exactly this pattern in light from a galaxy about 5.5 billion light years away, suggesting these molecules are abundant there.

But when New Mexico State University failed to find any evidence of the bands in six distant galaxies in 2006, this idea was put to question.

Now, the latest evidence seems to back up the idea that organic molecules are common elsewhere in the universe.

Using a very large telescope in Chile, a team from the University of Victoria, Canada, has found another galaxy about 2 billion light years away with telltale DIBs. This galaxy was found by concentrating on dusty-looking galaxies

The team now hopes that it will be able to delve further into the abundance of organic molecules in the galaxy.

"Finding such organic bands in other galaxies could help pin down when organic molecules first become abundant in galactic evolution, " said Chris Churchill of New Mexico State University.

"The goal is to work out when the ingredients for life first existed in the cosmos, which is a fascinating question scientifically, " New Scientist quoted Churchill as saying.

But the challenge for scientists is that nobody has worked out which molecules contribute to the signature of the interstellar bands. So, there is some uncertainty over the composition of the material.

"By observing the bands in many different galaxies, it may be possible to pin down the exact molecule or molecules, " says Michael Jura of the University of California in Los Angeles. (ANI)