On that day, the planet Saturn, with no help from either Jupiter or Uranus, will make its 170,000-mile-wide ring system disappear. How does a mere gas giant planet, without the benefit of a magic wand, smoke and mirrors, or even sleeves for that matter, manage to hide an estimated 35 trillion-trillion tons of ice, dust and rock fragments? Saturn itself, perhaps adhering to the magician’s code of never revealing how a trick is performed, is not talking. However, Linda Spilker, deputy project scientist for the Cassini Saturn mission at NASA‘s Jet Propulsion Laboratory in Pasadena, Calif., makes all known…
“Saturn has been performing the “ring plane crossing” illusion about every 15 years since the rings formed, perhaps as long as 4.5 billion years ago, so by now it is pretty good at it,” said Spilker. “The magician’s tools required to perform this trick are pure sunlight, a planet that wobbles, and a main ring system that may be almost 200-thousand miles wide, but only 30 feet thick.” All planets in our solar system wobble on their axes to some extent. This change of attitude eventually places a planet’s equator directly in line with the photons of light streaming in from the sun. This is called “equinox,” and on Earth it occurs every year about March 21st (spring equinox) and Sept. 22nd (autumnal equinox). On Saturn, it occurs twice during each 29 Earth-year-long orbit around the sun (about every 15 years). “Whenever equinox occurs on Saturn, sunlight will hit Saturn’s thin rings, the ring plane, edge-on,” said Spilker.”The light reflecting off this extremely narrow band is so small that for all intents and purposes the rings simply vanish.” Far from being a loss, a ring plane crossing provides a unique opportunity for scientists. The sunlight hitting the rings at 90-degree angles can illuminate, or throw shadows, revealing ring structures and oddities previously unseen.
