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2015 Aussie sky guide

A lunar eclipse, planetary encounters, comets and meteor showers top Ian Musgrave's list of what to see in the sky this year.

The night sky is always good for quiet contemplation, but sometimes our sky is the occasion for excitement. 2015 is no exception: this year we have a total lunar eclipse; some nice planetary encounters, two binocular-viewable comets that may become visible to the unaided eye and couple of meteor showers.

After last year's three rare occultations of Saturn, 2015 isn't quite as exciting in terms of planets blocking other bodies from view. But we do have a very good occultation of Venus by the crescent Moon.

So here's a quick rundown:

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Total lunar eclipse

Australia only gets to see one eclipse this year: but it's a very nice lunar eclipse. The eclipse is visible from all of Australia, although for Western Australia the early partial phases are in twilight. Sadly, the total phase of the eclipse is very short, with a mere 12 minutes of totality.

Lunar eclipses occur at pretty much the same equivalent local times across the country.

The start and finish times given are for the partial phases of the eclipse, when the umbra — the darkest part of the Earth's shadow — first touches and leaves the Moon respectively. The total eclipse starts six minutes before maximum eclipse, and finishes six minutes after.

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Planetary occultations

Occultations occur when one celestial body (most often the Moon) passes in front of a planet or bright star, obscuring it from view.

This year, the stand out event is the occultation of a three-quarter full phase (gibbous) Venus by the thin crescent Moon, visible in the early morning everywhere except Western Australia.

Although the occultation occurs during the morning twilight and ends after sunrise in most states, Venus is so bright that these events are easily seen with the unaided eye. The view is even better through binoculars, and in even a small telescope the gibbous shape of Venus will be easily seen. However, you will need to be very careful to make sure you cannot accidentally view the Sun in the final part of the occultation. Later on in the day you can use the Moon as a signpost to see Venus in the daylight.

The occultation of Uranus is visible in binoculars and telescope only, but may be of some interest.

Mars is occulted by the Moon during the daylight in central and Western Australia. This is a telescope only event for the experienced observer. Again, great care must be taken to avoid accidentally viewing the sun and damaging your eyes.

The Moon is a very obvious signpost when look at these events. Venus will be the brightest object near the Moon, while the others will require some experience to recognise.

Start watching about half an hour before hand to get set up and familiar with the sky. Although the Venus occultation is very easily seen with the unaided eye, it is best seen in a small telescope so you can see Venus's gibbous as it vanishes behind the Moon.

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Comets

2015 got off to a good start with the beautiful Comet C/2014 Q2 Lovejoy.

Later this year, two more comets will become bright enough to view in binoculars , and may even be visible with the unaided eye. They will be faint fuzzy dots to be sure, but faint fuzzy dots from the depths of space.

C/2014 Q1 PanSTARRS may be magnitude 3 in July, but it will be too close to the Sun to observe then. By the time it becomes visible in Australian skiesin August in the constellation of Crater, the cup, it is predicted to be a dimmish magnitude 7, visible only in binoculars.

Comet C/ 2013 US10 Catalina will be magnitude 5.4 (which is suitable for unaided eye detection under dark skies) from October to December, but its position low in the morning skies will make it difficult to see with the unaided eye. On the morning of 8 December the comet is close to Venus and the crescent Moon.

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Meteor showers

There are several iconic meteor showers that are not listed here, like the Perseids and Leonids, because they are too far north to see from Australia, or will have very poor activity this year. The rates are given for observation under dark sky conditions in the early morning, when the meteor showers point of origin is highest in the sky.

People in northern Australia generally see much higher rates than southern Australia for these showers. For example, in 2013 the Geminids were very poor in southern Australia, while folks in Darwin saw an outstanding display.

To see the meteors generally look north from 1 am in the morning, although for the Aquarids and Geminids rates are better around 3-4 am.

This year promises to be good for the Geminids, with dark skies for the shower, but the Full Moon washes out the Eta Aquarids.

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Planetary conjunctions

With Venus in the evening sky for the first half of this year, there will be some notable bright conjunctions as planets appear close to each other or prominent star clusters. These will make excellent evening viewing with the unaided eye.

On 21 February, Mars and Venus will be less than a finger-width apart in the evening twilight, with the thin crescent Moon close by. On 22 February, Venus and Mars are less than half a finger-width apart.

In April, the western evening sky is enhanced as Venus passes between the star clusters of the Pleiades and Hyades in the constellation of Taurus. On 11 April, Venus is just over two finger-widths from the beautiful Pleiades cluster. On April 21 the crescent Moon, Venus and the bright red star Aldebaran form a triangle which encompasses the Hyades cluster.

On 1 July, Venus and the bright planet Jupiter are less than a finger-width apart, low in the western evening sky.

In late August, Venus returns to the morning sky. Between 18 and 31 October Venus, Jupiter and Mars dance around each other in the morning twilight to the east.

In early November, the bright planets Jupiter, Venus and Mars line up in the eastern morning sky. On November 7 and 8, the crescent Moon joins the line-up.

About the author: Dr Ian Musgrave is an avid amateur astronomer. He writes the weekly sky updates for ABC Science and is science adviser to iTelescope.net. When not staring at the sky he is an equally enthusiastic molecular pharmacologist at the University of Adelaide, Australia. You can follow him on Astroblog for daily posts about astronomy, biology and life, the Universe and everything.



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