The Mystery Of Saturn’s Young Ring
Reigning majestically in the cold, dark outer kingdom of our Solar System, a quartet of enormous gaseous planets circle our Star. Saturn and Jupiter are our Solar System’s gas giant duo, and both are shrouded by deep, dense envelopes of gas. Saturn is the smaller of the two gas-giants, but it is larger than the two other, more distant planetary denizens of our Solar System’s outer limits–Uranus and Neptune–which are classified as ice-giants because they contain larger cores shrouded under thinner gaseous envelopes of blanketing gas. Saturn is a beautiful, distant world, famous for its enchanting, bewitching, and lovely system of rings, that are mostly composed of a dancing multitude of tiny, twirling icy fragments. The rings of Saturn are the most extensive planetary ring system of any planet in our Solar System, and in September 2015, a team of astronomers reported their study suggesting that the icy bits tumbling around in one section of Saturn’s rings are denser than elsewhere, and that this is possibly due to solid, icy cores. This finding could mean that this particular ring is considerably more youthful than the others.
Back in August 2009, a distant sunset on Saturn’s mesmerizing rings was carefully observed by astronomers who were part of NASA’s Cassini mission. It was the equinox–one of two periods of the Saturnian year when our Star shines brightly on the planet’s immense and majestic system of 鑽石淨度 edge-on. The event provided a valuable opportunity for the orbiting Cassini spacecraft to observe brief alterations in the rings that could reveal important clues about their intriguingly mysterious nature.
NASA’s Cassini spacecraft entered orbit around Saturn on July 1, 2004, and started to take some very revealing images of this beautiful planet, its rings, and its myriad moons. Although Saturn appears to be a calm, peaceful planet when it is observed from a great distance, the up close and personal observations derived from the Cassini probe showed how deceptive distant appearances can be. In fact, Cassini successfully managed to image the Great Springtime Storm that shook up Saturn in early 2011. The whirling, swirling tempest was reported by NASA on October 25, 2012, and this furious storm displayed an enormous cloud cover as big as our entire planet!
Saturn is tilted on its axis–just like our own planet. Over the long passage of its 29-year-long orbit, our Sun’s brilliant and illuminating rays of light travel from north to south over the gas-giant and its rings, and back again. The changing sunlight causes the temperature of the rings–which are composed of trillions of glittering, frozen bits of somersaulting ice–to vary from one season to the next. During the equinox, which lasts for only a few days, strange and weird shadows and wavy structures appeared and, as they lingered in the distant twilight of this faraway world, the rings began to cool.
In a study published in the planetary science journal Icarus, the team of Cassini scientists reported that one section of the rings seems to have warmed up during the Saturnian equinox. This somewhat toasty temperature provided a one-of-a-kind peek through a window of opportunity into the secretive interior structure of ring particles not normally available to curious astronomers.
Rings And Icy Things
In 1610, the great Italian astronomer Galileo Galilei turned his primitive telescope to the starlit sky, and became the very first person to see the rings of Saturn. Although reflection from the rings increases Saturn’s brightness, they cannot be seen from Earth with the unaided human eye, and Galileo was unable to see them well enough to discern their true nature. Galileo wrote to the Duke of Tuscany that “[T]he planet Saturn is not alone, but is composed of three, which almost touch one another and never move nor change with respect to one another. They are arranged in a line parallel to the zodiac, and the middle one (Saturn itself) is about three times the size of the lateral ones [the edges of the rings]”. Galileo went on to describe Saturn as possessing “ears”. In 1612, the plane of the rings was oriented directly at our planet and the rings seemed to vanish. The bewildered Galileo wondered, “has Saturn swallowed its children?”, referring to an ancient Greek and Roman myth in which Saturn (Greek, Cronus) devoured his own children to prevent them from overthrowing him. But, then, the mysterious structure reappeared in 1613, further confusing Galileo.