In 1610, the Italian
astronomer Galileo
was the first human to see the rings of Saturn. Galileo described the rings as "handles", not knowing they were separate from the planet. It wasn’t until 1655 that a Dutch astronomer, Christian Huygens, was able to note that the rings were a separate entity. In the early 1980’s, the Voyager 2 spacecraft took the first close-up images of Saturn and its rings. Voyager showed that the rings were made up of rock and ice particles. These particles varied in size from pebbles to giant boulders. The Hubble Space Telescope captured breath-taking pictures of our ringed planet in the early 1990’s. In 2004, another spacecraft, Cassini, will bring us close-up pictures of Saturn as well as land a probe on Saturn’s moon Titan.
Saturn is the sixth
planet from the Sun, and the second largest planet in the solar system.
It is about 9.4 times the size of the Earth. The rings of Saturn extend
roughly 81,000 miles (135,000 km) from the center of the planetary disk.
From Earth, the maximum size of Saturn's disk is 20 arcseconds, and together
with its rings it displays the apparent size of 46 arcseconds. Saturn reaches
a brightness of zero magnitude. Saturn has 18 known moons, Titan being
the largest. Over a 30-year period we will witness different views of the
rings (open or edge-on) because they are inclined 27 degrees to Saturn’s
orbit.
In March 2004, Saturn is at its best. It is high in the sky, almost overhead, in the feet of the constellation Gemini. This is prime time for viewing because we are
looking through thin atmosphere and steady air currents. When observing
the rings, you will notice a division known as the Cassini division. This
is an area sparse of rocks and particles that make up the rings. The Cassini
division is easily visible in small telescopes, such as a 60mm refractor.
A 10-inch or larger telescope will show another, smaller gap in the rings
called the Encke division. Other observable characteristics include atmospheric
features such as belts, zones, spots, and polar caps. Filters will help
enhance these atmospheric features (blue #80A or yellow #12).
This map shows
you where to find Saturn in 2004. In March, Gemini is high overhead after dusk. Saturn is the brightest starlike object in this region, with the exception of Sirius, the Dog Star, which is south in the constellation Canis Major.