Scientists Spot Spiral Structure at Edge of Solar System

The Oort cloud is traditionally thought of as a vast shell of perhaps trillions of icy objects encasing our solar system, serving as the final boundary between us and the dark reaches of interstellar space. But it's not a homogenous mass. In reality, astronomers don't yet have a complete picture of what it looks like — and are only beginning to glimpse just how complex its makeup might be. Now, in a new study set to be published in The Astrophysical Journal, a team of researchers from the Southwest Research Institute in Colorado say they've discovered a fascinating aspect about the Oort cloud's interior that can change how we view its overall shape: a spiral structure that's similar to the spiral arms of our galaxy. At a heliocentric distance ranging from 10,000 to 100,000 astronomical units — each unit being equal to the distance between the Sun and the Earth — the Oort cloud is both incredibly vast and totally out of reach. There's little sunlight to speak of, and observing the cl ... Read full article.