Mars not as big as the Moon

Like many astronomical institutions, CSIRO's Australia Telescope National Facility, has had many enquiries about a circulating email claiming that Mars, or some other planet, will appear as big as the Moon with the unaided eye on August 27th. It will not.

The email is a corrupt version of an email from August 2003 when Mars did, on an astronomical scale, make a relatively close pass to Earth. As well as leaving out the year, 2003, the email also does not mention that a telescope is needed to see Mars as big as the Moon.

However, you can expect a great view of Mars over the final months of 2005, similar to that seen in August 2003.

An event such as this is termed "opposition" and occurs when the Earth passes Mars (or any other planet) in its orbit around the Sun. For the Earth and Mars this occurs every 26 months so Mars will actually be in opposition again during early November 2005.

During this year's event Mars will pass within 69.4 million km of Earth as compared with 55.7 million km in 2003 so will not be as bright as it appeared then. It should therefore appear bright in the north-eastern sky (for Southern Hemisphere viewers) after twilight in late October and early November, peaking in brightness on the 7th.