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The Sweet Signal of Sugar in Space

Astronomers have discovered the first extraterrestrial sugar, sweetening up the center of the Milky Way. Because sugar molecules are essential ingredients of DNA and other biological building blocks, the finding will help scientists model how life might have begun.

The molecular gas cloud that sits near the core of the Milky Way was already known to contain two molecules with the same atomic ingredients as glycolaldehyde, the newly discovered sugar. It, methyl formate, and acetic acid are built of two carbon, four hydrogen, and two oxygen atoms.

Knowing about the other molecules, radio astronomer Mike Hollis of Goddard Space Flight Center in Greenbelt, Maryland, decided to look for glycolaldehyde. He used the standard method to detect distant molecules: looking for a radio frequency fingerprint. As molecules tumble through space, they absorb and emit photons. This causes them to radiate faintly at a characteristic set of frequencies. When Hollis and his team analyzed data from 6 days of observations with the 12-meter radio telescope on Kitt Peak in Arizona, they found the sugar's fingerprint. The paper has been submitted to the Astrophysical Journal.

Laboratory experiments show that this simple sugar molecule reacts with methyl formate and acetic acid to form more complex sugars, beginning a long chain of chemical reactions that could form biological molecules. Now the same chain is possible in space. "The glycolaldehyde finding indicates that sugar synthesis may occur in interstellar clouds," says Hollis. The discovery is a small additional piece in the very large and complex puzzle of how the complex molecules of living organisms may have spontaneously formed in space, says chemist Norman Pace of the University of Colorado, Boulder.