Sydney Observatory key astronomical events haveoccurred in recent years, most notable are Halleys Comet (1986), The impact of Shoemaker Levy on Jupiter (1994), Mars at its closest encounter (2003), transits of Venus (2004, 2012), Comet McNaught (2007), planetary alignments and eclipses. Thousands of people came to the Observatory to view these through telescopes and to see relevant exhibitions. Further the Observatory provided information about these events to many more people either directly or through the media. In 2008, for the 150th anniversary, the Signal Station building was stabilised, one of the original two flagstaffs re-constructed and an archaeological investigation commenced around the
Rings of Saturn has been attributed to a perturbation caused by impact of material from Comet Shoemaker-Levy 9 in 1994. The C Ring is a wide but faint ring located inward of the B Ring. It was discovered in 1850 by William and George Bond, though William R. Dawes and Johann Galle also saw it independently. William Lassell termed it the "Crepe Ring" because it seemed to be composed of darker material than the brighter A and B Rings. Its vertical thickness is estimated at 5 m its mass at around 1.1 kg, and its optical depth varies from 0.05 to 0.12. That