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
Comet Shoemaker–Levy 9 Despite published predictions, astronomers had not expected to see the fireballs from the impacts and did not have any idea in advance how visible the other atmospheric effects of the impacts would be from Earth. Observers soon saw a huge dark spot after the first impact. The spot was visible even in very small telescopes, and was about (one Earth radius) across. This and subsequent dark spots were thought to have been caused by debris from the impacts, and were markedly asymmetric, forming crescent shapes in front of the direction of impact. Over the next six days, 21 distinct impacts