Cassini's Discovery of the Cassini Division
- When
- 1675
- Where
- Paris Observatory
- Episodes
- 1
In 1675, Giovanni Domenico Cassini observed Saturn at the Paris Observatory and identified that the ring system consisted of multiple smaller rings separated by gaps, the largest of which is now known as the Cassini Division.
Episodes
Background and detail
Background. Saturn possesses the most extensive ring system in the Solar System, composed primarily of water ice particles. While Galileo first observed the rings in 1610, he could not discern their true nature. The rings are not visible to the naked eye from Earth, requiring telescopic observation to reveal their structure.
The 1675 Observation. Using a refracting telescope with a 2.5-inch objective lens and 90x magnification, Cassini determined that Saturn's ring was composed of multiple smaller rings with gaps between them. This observation was made at the Paris Observatory.
Naming and Structure. The largest gap identified by Cassini was later named the Cassini Division. It separates the A and B rings, which are the densest parts of the Saturnian ring system. The rings are named alphabetically in the order they were discovered, with A and B identified in 1675.
People involved
- Giovanni Domenico Cassini · Astronomer who discovered the division
Sources
- Rings of Saturn Wikipedia, revision of 2026-09-21
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