By Tom Burns
For those of us who pursue the sky, the first view of Saturn is often described as a life-changing experience. We spend our lives trying to replicate the jaw-dropping wonder of that first view.
If you have even a small telescope, point it at that bright yellowish point of light in the constellation Virgo. The rings will be small, but they are very distinctly and weirdly there. You’ll also see Saturn’s brightest moon, Titan, nearby.
“Is it real? How can that be?” kids and their parents often ask as they stare through the big telescope at Perkins. Yes, my friends, there is hope for America’s youth.
The “rings” look like a single ring most of the time. However, if you have a larger telescope (or make a trip up to Perkins over the next couple of months, hint, hint), look carefully at the ring. You may see a thin, dark line running all the way around the ring. The line looks much like a division in a phonograph record. (If you’ve never seen a phonograph record, please consult the collection of Strawberry Alarm Clock records in your parents’ attic. Then ask yourself what your parents were really like at your age.)
You’re looking at Cassini’s division, the first of many gaps in the ring discovered at telescopes got bigger over the years. As it turns out, Saturn has thousands of those concentric divisions, but you’ll need a spacecraft cruising by the planet to see them all.
We owe it all to a Dutch astronomer, lens grinder, mathematician, inventor, gambling theorist, clock maker, and visionary. The guy just couldn’t keep a job. With a telescope of his own design and construction, he discovered both the rings of Saturn and its largest moon.
In fact, the first views of Saturn revealed no rings at all. In 1609 or 1610, Galileo, who first looked at the planet with a tiny telescope, thought he saw a lump on each side of the planet’s disk. He hypothesized that Saturn was a triple planet or an early advertisement for the Mickey Mouse Club. I can’t remember which.
Okay, okay, I’m kidding. Walt Disney didn’t invent Mickey Mouse until 1623.
The serious fact is that it took one of the greatest geniuses of all time to allow humans to finally see the rings.
Christiaan Huygens was already famous in scientific circles when he undertook the redesign of the terrible lens-based, refracting telescopes of the time. With his brother, he designed, ground, and polished an exceedingly thin lens only 2 inches in diameter to partially eliminate the color distortion, called chromatic aberration. For the same reason, his first telescope was long – over 10 feet. The eyepiece was also of his own design. The Huygenian eyepiece, as it was called, dominated telescope use for many years, and is still in use to this day in inexpensive refractors.
By 1655, he had produced a lens of such great clarity that he discovered Saturn’s largest moon, which he called Titan. (In Greek mythology, Saturn was not, strictly speaking, a god but a
Titan, which shows that Huygens knew a bit about ancient mythology, among his many other accomplishments.)
He began creating lenses of such high magnification that they had to be placed in tubes as long as 23 feet. These instruments were awkward to use, to say the least. They were suspended from ropes on tall poles, and it took Zen-like patience to keep them pointed.
And yet he did so, hour after hour, night after night. By 1658, he made the discovery for which he is most-often remembered by astronerds around the planet. Saturn, he wrote, “is surrounded by a thin, flat ring, nowhere touching.”
Of course, no one believed him. This supposed revelation was weird beyond belief. Huygens persevered, however. By carefully calculating the motions of Earth and Saturn, he predicted that in 1677, the ring would be so inclined that from Earth we would see it edge-on. The ring is so thin, he wrote, that we might not be able to see it at all. As astronomers trained their much-improved telescopes at the planet during the summer of that year, they discovered that the ring was gone! Weirdness compounded upon weirdness, but one thing was certain. Huygens was right.
Tom Burns is the director of Perkins Observatory. He can be reached at firstname.lastname@example.org.