Saturn’s rings are disappearing. But, not to get all Henny-Penny about it, I should add they’ll be sliding back into view, splendid as ever.
The queen of planets takes 29 years, 6 months to orbit the sun. It is tilted at an angle of 27.3 degrees, according to a NASA site, “Frequently Asked Questions About Saturn’s Rings,” LOCATED HERE.
“Twice during the 29.5 years, the rings are edge-on to the Sun,” NASA notes.
Pretend the rings extend to the sun; that’s the ring plane. Earth is close to the sun as seen from Saturn, and we periodically pass through the ring plane, allowing us to see the rings from their edge instead of above or below.
“Since Saturn’s rings are so thin, when they are edge-on to the Earth, they appear to disappear when viewed with a small telescope,” adds NASA.
Celestial mechanics dictate that every half-orbit of Saturn — that is, sometime during the 15-year period — Earth will pass through the ring plane either once or three times. (That doesn’t mean it happens exactly every 15 years; the half-orbit is 15 years and during that interval we cross the ring plane.)
The last time the rings were edge-on to Earth was in 1996.
The next will be on Sept. 4, 2009; however, from our viewpoint Saturn will be so close to the sun it will be difficult or impossible to observe. Presently our world is heading toward the ring-crossing and the rings seem to be tilting more and more. Now they are so close to edge-on, only 4 degrees thick, that they don’t seem much like rings.
“Saturn looks like a planet with a javelin sticking through it,” said Patrick Wiggins, NASA solar system ambassador to Utah.
I took this photo around 3 a.m. on Sept. 19, 2003, from the roof of the Regent Street parking terrace, downtown Salt Lake City. The planet was in classic form, displaying beautiful rings and divisions.
[My 2003 view of Saturn as we normally see it]
The rings reflect half of the light bouncing off the system and when they are seen from the side the overall light is much less intense. Much of the sunlight reflects into space where we can’t glimpse it. That’s actually an advantage to observers of other phenomena, just as it’s better to look at the Milky Way when the moon’s not around. A bright moon washes out contrast and we can’t see details of the filmy pathway. The usual brilliance of Saturn washes out its moons.
The dimming that is going on now means the solar system’s second-largest planet is not putting out nearly as much glare; consequently, other nearby objects are easier to see.
This is a photo I took early Thursday morning from the Millard County desert. Unfortunately, the air was turbulent and Saturn kept popping into and out of focus so this isn’t the finest depiction. But from 861 million miles away, we can see the rings nearly edge-on and several moons.
[Saturn’s current look]
From the top, the photo shows Tethys above the rings; Saturn; Enceladus, nearly hidden on the lower side of the rings; Dione; Rhea and Titan. The last is the second-largest moon in the solar system and the only one with an atmosphere heavier than a sprinkling of gas atoms per crater.
The frigid air above Titan is so dense it hides the surface from Earth-based telescopes. My crude view gives a hint of the Titanic atmosphere, with its slightly ruddy hue.