Chiral molecules are "handed" molecules that are mirror images of each other - one is a right-handed version, the other left. They have the same properties in terms of characteristics like freezing and melting point, but they interact very differently with other molecules. Most pharmaceuticals are chiral, and while one of the twin compounds serves a useful purpose, the other is not effective and could potentially be harmful. Science Magazine explains chirality and an associated new discovery in the video above.
Interestingly, chiral molecules have been detected in space for the first time. After using radio telescopes to peer into the center of the Milky Way about 28,000 miles away, they detected evidence of propylene oxide, a chemical used back on Earth for making polyethylene plastics.
The discovery bolsters the idea that complex molecules could form on grains of ice inside clouds of diffuse interstellar gas and dust, as many current models of evolving solar systems propose. Could this discovery help explain why on Earth we encounter "homochirality" - the domination of one version of the handed molecule - so often? Maybe. It could also help us figure out some of the mysteries surrounding the origins of life.