The Milky Way. (Photo: NASA/JPL-Caltech/S. Stolovy)

Here is a strange thing about your body that you might not have known: all of the amino acids in it are “left-handed.” These compounds have two forms—mirror images of each other that share many basic properties but that differ in their chemical reactions. Often, the two forms are called “left-handed” and “right-handed,” and they’re a bit of a mystery. Why do they exist? And what’s the relationship between life as we know it and this distinction?

In one theory about how life on earth began, these “chiral” molecules landed on this planet from space and helped kickstart the process. For that theory to have a chance of being correct, though, there need to be chiral molecules somewhere other than our own solar system.

Until now, no one had found one, but this week a team of scientists published a paper in Science detailing the discovery of the first chiral molecules in interstellar space.

How does one find a molecule in space? This group of scientists used sensitive radio telescopes, which detected “three particular wavelengths of radiation that had been absorbed by the substance as they passed through the cloud,” Science Magazine reports. The molecule was propelyne oxide, in a shell of gas, in Sagittarius B2.

Finding a chiral molecule that far away doesn’t explain the origin of life on earth, or solve the mystery of the molecules’ right- and left-handedness. But it does indicate that scientists who are studying this might be on the right track to understanding a very big question: How did life on earth begin?

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