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
Astronomical symbols Ω (capital omega), which was originally a typographical substitute for the astronomical symbol. The symbols for aspects first appear in Byzantine codices. Of the symbols for the five Ptolemaic aspects, only the three displayed here—for conjunction, opposition, and quadrature—are used in astronomy. Symbols for a comet (☄) and a star () have been used in published astronomical observations of comets. In tables of these observations, ☄ stood for the comet being discussed and for the star of comparison relative to which measurements of the comet's position were made. Astronomical symbols Astronomical symbols are abstract pictorial symbols used to represent astronomical