Image: Polycyclic aromatic hydrocarbons
T. Pyle / SSC-Caltech / NASA / JPL
An artist's conception symbolically represents the complex organic molecules, known as polycyclic aromatic hydrocarbons, that have been detected in the early universe.
By Senior science writer
updated 7/28/2005 5:52:53 PM ET 2005-07-28T21:52:53

The stuff of burnt toast, auto emissions and life itself has been spotted in galaxies so far away they are seen at a time when our universe was just one-fourth its current age.

The discovery of organic molecules, called hydrocarbons, shows that the raw materials for life were present long before our solar system formed.

Scientists do not know how life made the jump from organic material to biological material, so the finding says nothing about whether there is or ever was life elsewhere in the universe.

The galaxies are about 10 billion light-years away, so they are seen as they existed 10 billion years ago. Earth is 4.5 billion years old, and the universe has been around for about 14 billion years.

A light-year is the distance light travels in a year, about 6 trillion miles (10 trillion kilometers).

"These complex compounds tell us that by the time we see these galaxies, several generations of stars have already been formed," said George Helou of the Spitzer Science Center at the California Institute of Technology in Pasadena, Calif. "Planets and life had very early opportunities to emerge in the universe."

The galaxies were imaged with NASA's Spitzer Space Telescope.

PAHs that refresh
The large molecules, called polycyclic aromatic hydrocarbons, are made of carbon and hydrogen and are considered to be among the building blocks of life. They are common on Earth, forming naturally and also whenever you overcook a burger, drive your car or somehow otherwise burn carbon-based material.

The hydrocarbons are also found throughout our Milky Way galaxy. It is not too surprising to find them in more distant places, but scientists until now had not pinned down how early in the universe they formed.

In the leading theory of the universe's development, things were mostly hydrogen at first. As stars formed and died, new and heavier elements were added to the mix, such as oxygen and metals. The soup of the cosmos got more complex with each generation of stars. Somewhere in there, elements combined to form hydrocarbons. Add a little water, stir, and somehow life begins.

The study, to be published in the Aug. 10 issue of the Astrophysical Journal, was led by Lin Yan of the Spitzer Science Center.

Found in star-forming galaxies
The organic compounds were found in galaxies that host intense star formation. The galaxies are nearly invisible in regular light, but Spitzer images the heavens by recording infrared light, which represents heat.

By splitting the infrared light into its spectrum of colors, scientists were able to identify the organics.

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