Observers in south-western Australia can witness a great astronomical event on the morning of 6 October when Jupiter, Ganymede, Io and Callisto are occulted by the Moon. This is the view at 4.50am WST as Jupiter is about to be occulted with Callisto waiting its turn. Graphic made using Guide 8 www.projectpluto.com

Observers in south-west Australia are in for a real treat on the morning of 6 October when a waning 73 percent illuminated gibbous moon totally occults the gas giant Jupiter and three of its Gallilean satellites. It will be fascinating to see Jupiter gradually move behind the lunar limb over the course of a few minutes. For observers in a small part of south eastern Australia there is a total occultation, with Hobart favoured and grazing events in Adelaide and Melbourne, but unfortunately the Sun is above the horizon.

The city of Perth will see the disappearance of Ganymede, Io, Jupiter and Callisto at the bright lunar limb (Europa is hidden behind Jupiter at the time of the occultation) and the reappearance too, although the Sun is just rising so making it more difficult to observe, although the Moon is still well up. For the reappearance it's important to know where at the Moon's edge Jupiter and its moons are predicted to reappear. Astronomers use a term called 'position angle' (PA) to describe the relative location of two bodies, most commonly doubles stars or in this case the lunar limb and Jupiter. One easy way of visualising PA is the Moon as a clock-face with north, east, south and west around its edge with a total of 360°, measured anti-clockwise from north. So if a star reappears at due north on the lunar limb the PA is 000°; due east, 090°; due south, 180° and due west, 270°. Jupiter and its moons will reappear at PA 323 to 326°, the north-western lunar quadrant.

Jupiter reappears at 5.52am, following Ganymede and Io minutes earlier. Callisto reappears at 6.12am but the Sun is up by then. Graphic made using Guide 8 www.projectpluto.com

This event can be viewed in binoculars but observing with a driven telescope where some magnification can be brought to bear is a much better option. Imagers should have a good time of it with perhaps some enterprising amateurs securing some video footage.

Astronomy Now would be delighted to receive any images or observing reports; send them to gallery2012 @ astronomynow.com

This special publication features the photography of British astro-imager Nik Szymanek and covers a range of photographic methods from basic to advanced. Beautiful pictures of the night sky can be obtained with a simple camera and tripod before tackling more difficult projects, such as guided astrophotography through the telescope and CCD imaging.
 U.K. STORE
 E.U. STORE
 U.S. & WORLDWIDE STORE

Hubble Reborn
Hubble Reborn takes the reader on a journey through the Universe with spectacular full-colour pictures of galaxies, nebulae, planets and stars as seen through Hubble's eyes, along the way telling the dramatic story of the space telescope, including interviews with key scientists and astronauts.
 U.K. STORE
 E.U. STORE
 U.S. & WORLDWIDE STORE

The Planets
From tiny Mercury to distant Neptune and Pluto, The Planets profiles each of the Solar System's members in depth, featuring the latest imagery from space missions. The tallest mountains, the deepest canyons, the strongest winds, raging atmospheric storms, terrain studded with craters and vast worlds of ice are just some of the sights you'll see on this 100-page tour of the planets.
 U.K. STORE
 E.U. STORE
 U.S. & WORLDWIDE STORE

3D Universe
Witness the most awesome sights of the Universe as they were meant to be seen in this 100-page extravaganza of planets, galaxies and star-scapes, all in 3D!
 U.K. STORE
 E.U. STORE
 U.S. & WORLDWIDE STORE

This new poster features some of the best pictures from NASA's amazing Mars Exploration Rovers Spirit and Opportunity.
 U.K. STORE
 E.U. STORE
 U.S. & WORLDWIDE STORE