BY TUMA HAJI
Imagine the captivating, enormous rings of Saturn captured in all of their glorious, vivid detail. The blur of rock and ice circling the ball of gas with 53 moons, one with its own atmosphere, orbiting just outside the rings. These exact spectacles were showcased by associate professor of astronomy, Charles Nelson, in the weekly Friday lectures at the Drake Observatory.
This past Friday, the lecture focused on the images captured by the late spacecraft, Cassini, before its demise last week. Using a New York Times presentation, titled “100 Images From Cassini’s mission to Saturn,” Nelson lectured in depth about the various aspects of Saturn, its rings and its moons. The vivid images from Cassini highlighted the thousands of rings that circulate the gaseous planet.
Nelson explained the unique rings of Saturn are created by the overbearing tidal force of the gravitational pull of the moons. Due to the fact that the moons are held in orbit by the gravitational force exerted between their masses and that of Saturn, the moon is subsequently ripped apart by the exponentially stronger gravitational field of Saturn.
If the moons do not surpass the Roche Limit of Saturn, where their gravitational force is not threatened, the moons continue to orbit outside of the rings. The moons that are ripped apart by Saturn’s gravitational exertion orbit in circulation around the gas giant. By orbiting in elliptical motion, the rings avoid collision with other rings, while the moons always orbit outside of the rings.
Although rings are not structurally exclusive to Saturn (Jupiter, Uranus, and Neptune also have rings), Nelson, taking an evolutionary stance, said that the reason Saturn’s rings are “so spectacular is because they’ve been recently (relatively) replenished by the moons.”
He went on to explain that Saturn is more than just a combination of rings.
“It’s a system of moons that get together and operate together,” Nelson said.
Using a piece of paper to demonstrate an idea of the density of the rings, Nelson discussed how the rings are the thinnest structures in the known universe. Despite expanding nearly 250,000 kilometers in diameter, the rings are extraordinarily thin, with a density of less than one kilometer.
The lecture also expounded on the surface and atmospheric attributes of Saturn. The planet’s gaseous atmosphere is believed to have the highest Albedo number, which measures the amount of light reflected back from a surface. Nelson also discussed the craters of the moon, explaining how the abundance of craters correlates with the age of the surface area of the moons. Saturn’s largest moon, Titan, is the only known moon to have an atmosphere. The moon also has lakes of methane and ethane.
“Serendipitous discoveries like this are absolutely fantastic,” Nelson said.
Many in the audience, which consisted of many Des Moines community members as well as Drake students and faculty, seemed to also be fascinated by the pictures of Saturn. The audience raised many thought-provoking questions, ranging from the cost of launching spacecrafts into the universe to the temperature of the atmosphere.
Traci Narago, a mother who brought along her two children, expressed her enjoyment with the lecture.
“I think it was very informative and educational,” Narago said.
Her son, Tyler, agreed with her, adding that the pictures were the most interesting aspect of the lecture.
Outside the observatory, three telescopes were set up, offering the attendees views of Saturn and Messier 13, a globular star cluster, as well as the closest galaxy to our own, Andromeda.
David Stapleton, one of the members of the observatory set-up crew, explained that simple telescopes are basically tubes with a couple of mirrors in it to reflect back the image.
Narago, after looking at Saturn through the telescope, described the rings as being barely visible. Tyler thought it was “pretty amazing seeing from that distance.”
His younger sister, Olivia, echoed his sentiments, comparing the rings to a “dot with ears with space in between the head.”
Community lectures, called “Public Nights,” at the Drake Municipal Observatory occur every Friday at 8:00 pm. The topic of the next lecture, occurring Sept. 29, is titled “‘Can’t Hit the Broadside of the Moon’ or Anything Else,” which discusses the difficulties associated with dispatching spacecraft instrumentation.