Explore Alliance Presents: How Do You KNOW? – Episode #23: 'Sketching Saturn'

Sketching Saturn: The Box and Rectangle Method

The first discoveries the system of the rings and moons around Saturn predate photographic technology, and therefore had to be described in text and very importantly, in drawings.

Galileo was the first person to perceive the ring system around Saturn in 1609, but Galileo was unable to comprehend what he was seeing. Galileo’s tiny telescope with its 30 mm objective was too small and the magnification too low to enable him to clearly resolve the rings. Christian Huygens used a 150 mm (6-inch) reflector of his own design in 1665 to enable him to see the ring structure clearly as a belt of material encircling the planet.

Giovanni Cassini explored Saturn in much greater detail and by 1675 Cassini had discovered four minor moons (Iapetus, Rhea, Tethys, and Dione) as well as the major gap in the rings of Saturn. Cassini also discovered a variation in the brightness of Iapetus which the astronomer correctly attributed to hemispheres with different albedos (brightness); the dark region on Iapetus is named Cassini Regio and the main gap in the rings of Saturn is named the Cassini gap all in his honor.

In this episode of 'How Do You KNOW?', Dr. Barth will share techniques that he developed for making more accurate drawings of Saturn for your observing logs, and to share observations with your friends.