One of the most alluring things about space is that because of its very vastness, it’s possible for truly enormous things to effectively be hidden in plain sight for centuries, even millennia. Then, one day, some clever stargazers think of a new way to look at part of the sky that’s been stared at countless times before, and suddenly something truly magnificent appears.
This week, scientists at NASA’s Jet Propulsion Laboratory, working with the Spitzer Space Telescope, identified a new ring around Saturn — a ring so vast that its size is hard to comprehend.
The inside edge of this ring is some 3.7 million miles away from Saturn, and the ring itself is 7.4 million miles wide. It’s not very dense; at 20 particles per cubic centimeter, you couldn’t walk around on it. That’s reason it wasn’t spotted sooner. Within it orbits Saturn’s moon Phoebe, which is one of the planet’s most distant satellites; both Phoebe and the ring, in fact, orbit in the opposite direction of the rest of the moons and rings.
The ring was found by University of Virginia-Charlottesville astronomer Anne Verbiscer and her colleagues, who used the Spitzer Telescope’s infrared imaging system to identify the giant ring. According to the JPL website’s article on the discovery, infrared was the key to finding the ring.
“The ring would be difficult to see with visible-light telescopes,” the article reads. “Its particles are diffuse and may even extend beyond the bulk of the ring material all the way in to Saturn and all the way out to interplanetary space. The relatively small numbers of particles in the ring wouldn’t reflect much visible light, especially out at Saturn where sunlight is weak.”
Added Verbiscer: “The particles are so far apart that if you were to stand in the ring, you wouldn’t even know it.” Of course, he means “float around in the ring.”