Page 63 - Astronomy - October 2017 USA

The iconic planet image
for amateur astronomers,
Saturn features a yellow-
golden planetary sphere
surrounded by the most
famous rings in the universe.
DAMIAN PEACH

dark and a bit ragged on the upper edge with a hint of a “bulge” Voyagers launched, the world learned that Uranus, like Saturn,
on the lower section. The other band was fainter, and we could has a system of rings. MIT astronomer Jim Elliott made the dis-
see little detail on the cloud tops of Jupiter. Europa and Callisto covery while watching Uranus occult, or pass in front of, a star, to
appeared as two starlike objects. Saturn was lower in the sky, but study the planet’s atmosphere and other features. To his surprise,
was beautiful as always. The rings were not edge-on, but were the star faded in and out before it disappeared behind the planet,
partly closed. Unsurprisingly, we couldn’t make out any cloud providing evidence for the rings. Then, in 1979, Voyager 1
details with a scope of this size. revealed that the king of planets, Jupiter, is also surrounded by
The 6-inch refractor we used that morning in 1978 was pretty four thin dust rings.
typical of the kinds of scopes many amateurs used in the 1960s, Flipping through my observing journals, I came across an
’70s, ’80s, and beyond. Browse through the ads of any astronomy unusual night several years later, on July 17, 1985. I was observing
magazine of the time, and you will see ads for the Criterion both Jupiter and Saturn. The Voyager rendezvous with these two
Dynascope RV-6 reflector, Unitron 2.4- and 3-inch reflectors, and gas giants was over, and Voyager 1 was on its way out to the edge
the orange squat tube of an 8-inch of the solar system. That night, I was
Celestron telescope. using a Celestron 8-inch telescope and a
Our proverbial socks were range of eyepieces. At about 250x, both
Resetting the solar system about to be blown off as planets held up well with clear details. I
What we didn’t appreciate fully quite could see at least five bands on Jupiter
yet, in 1978, was that all of us who were Voyager 1 made its closest and the shadow of the moon Io as it pro-
into amateur astronomy were about to gressed across the disk of Jupiter.
have our proverbial socks blown off as approach to Jupiter. Saturn was gorgeous, as always. My
Voyager 1 made its close approach to drawing shows the rings almost wide
Jupiter in March 1979 and Voyager 2 in July of the same year. open. I noted one cloud band and the Cassini Division as quite
The astounding detail of the images returned by these spacecraft clearly visible. As I watched Saturn drift by in my field of view, I
forced us to totally rethink not only what we knew about this thought of all we had learned about the ringed planet during the
giant planet, but the solar system as a whole. past few years. In the C8, I could easily see features that had been
In the early years of my planetarium career, I used astronomy observed for the past three centuries. Now we knew that Saturn’s
books written by Isaac Asimov as an authoritative source for rings were far more complex than what any ground-based tele-
school and public programs. One of those was Jupiter, The Largest scope could show. In the high-resolution images returned by
Planet. According to Asimov, Jupiter had 13 moons. The Voyagers Voyager 2, astronomers discovered hundreds of thin rings, some
added three more moons to the realm of Jupiter. Today we count only a few feet thick.
51 moons with names, and another 18 that orbit anonymously
around the giant planet. Imaging the outer planets
Planetary discoveries were happening even before the space- I have always enjoyed drawing what I see in the eyepiece. Many of
craft departed. On March 10, 1977, just months before the my contemporaries, however, have produced images of the outer

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