Thursday, October 08, 2015
Occultation of Venus, morning Friday October 9, 2015
On the early morning of October the 9th crescent Venus is occulted by the crescent Moon as seen from central and eastern Australia, with eastern Australia having the best view of the disappearance. Central Australia sees Venus reappear in the twilight, while for most of the east coast Venus reappears after sunrise.
The occultation occurs with the Moon low above the horizon at the start for the eastern states, and very low or just below the horizon for the central states. For example from Alice Springs Venus is below the horizon when the occultation starts, and Venus emerges from behind the Moon at 5:44 am ACDST. This is very close to the horizon. Venus disappears behind the bright edge of the Moon, which is easily visible and a ready signpost to Venus.
While the occultation is easily visible to the unaided eye, the sight in even a small telescope of the "half-Moon" Venus disappearing behind crescent Moon will be rather awesome. It is advisable to set up and practise on the Moon a day or so before the event, so you are familiar with your telescope set-up. Set up at least half an hour ahead of time so that you can be sure everything is working well and you can watch the entire event comfortably (trying to focus your telescope on Venus moments before the occultation will cause a lot of unnecessary stress). Venus will be clearly visible to the unaided eye near the Moon.
Venus reappears from behind the Moon after sunrise in the eastern states, and in bright twilight in the central states. Despite this, Venus will be readily observable. You may have to make sure your scope is tracking on the dark side of the Moon before it is lost in the twilight though.
Timings in Universal Time for a number of cities is here. The table below shows the occultation times for selected cites at the various local times.
|Place||Moon rise||Disappears Bright Limb||Reappears Dark Limb||Astronomical Twilight||Sunrise|
As well, Adelaideians will be treated to a bright pass of the international space station at 5:40 am ACDTS above the crescent Moon and Venus (In Melbourne the ISS passes over at 6:15 AEDST, and in Brisbane at 3:38 AEST).
During the occultation, Mars and Jupiter rise to form a line with the Moon. After the occultation is over it is possible to see Venus in the daylight using the crescent Moon as a guide (if you are careful to avoid the Sun).