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Explorers Team head downunder for Total Eclipse

Our sister company, Explorers Astronomy are on their way to Australia to prepare for the forthcoming Australian Eclipse 2012 trip. On Wednesday 14 November (australian time: 13 November pm UK) a total eclipse will occur just after sunrise.

The Explorers team have spent months looking for the right spot for the 228 astro-mad travellers journeying downunder for the event. Combining the highlights of Australia with this amazing solar eclipse, the astro team are heading to Palm Cove for the actual viewing. Palm Cove is is situated along the Pacific Coast just 20km north of Cairns. The beautiful palm fringed, sandy beach has won many awards and is a delightful place to wander, so this is a beach and astro tour!

What is a total solar eclipse?

A total solar eclipse is one of the most beautiful events of the natural world. It is an extraordinary quirk of geometry that the apparent sizes of the Moon and Sun are nearly equal in our sky and when the Moon passes directly between Earth and the Sun the result is a spectacular piece of natural theatre for those lucky enough to be within the narrow band of the Earth's surface beneath the shadow. The following notes offer some details of what to watch for:

First Contact: The moment when the first small bite appears in the edge of the Sun as the Moon starts to pass over it.

Second Contact: As the Moon completely covers the Sun, the razor thin solar crescent breaks up into a chain of beads which gradually wink out. These are known as Baily's beads and are a familiar feature of total eclipses. When the last of the beads disappears totality has started.

Totality: Just as the eclipse becomes total, for a second or two you will see a bright red streak along the limb of the Moon. This is an upper layer in the solar atmosphere called the chromosphere. It is quite bright though not as bright as the photosphere, the region of the sun's atmosphere that we normally see.

The most noticeable feature during totality is the solar corona which is the outer atmosphere of the Sun that is only visible to the naked eye during a total eclipse. It consists of pearly-white streamers radiating outwards.

During totality one of the most stunning features are the prominences which are flame like appendages to the chromosphere which may be seen at any location round the eclipsed Sun, perhaps being larger and more spectacular at times when the Sun is very active. It is also interesting to note that as the Moon moves across the Sun during totality, prominences in the area where second contact took place start to be covered up whereas others in the vicinity of where third contact is about to occur become larger as the Moon uncovers them.

Among the most dramatic features of an eclipse are the colours during totality. The disk of the Moon is completely black, surrounded by the pearly-white of the corona with occasional flame red prominences. The sky is a deep purple-blue and around the horizon the sky is usually an orange colour reminiscent of sunset. This strange mixture of colours can make everyday objects look positively surreal.

A glow around the horizon is due to sunlight outside the shadow of totality being reflected inwards. The actual colour can vary from reddish-orange to yellow.

During totality the sky is not particularly dark so only the brightest stars may be seen however it is worth having just a quick glance around the sky to see which stars and planets are visible. There is always the possibility that totality will reveal a comet close to the Sun which had not been observed before due to its proximity to the Sun.

Third Contact: The first sign that totality is drawing to an end is when the chromosphere starts to emerge from behind the rim of the Moon at the location where the photosphere will reappear at third contact. This occurs just a second or two before third contact and gives a good warning that the Sun is about to reappear. If you are using optical equipment to observe totality this warns you to now look away before the light of the photosphere reappears. The ‘diamond ring' is one of the most dramatic features of the whole eclipse. As the first point of the photosphere reappears, we see something that resembles a giant diamond ring in the sky with the small portion of the photosphere being the diamond and the rapidly fading corona being the rest of the ring.

At second contact our eyes are used to the bright light and can perceive the last bead as a small point. However our eyes become dark adapted during totality and so the reappearance of the Sun can be dazzling.

Fourth Contact: The moment when the Sun is completely restored.

 

Look out in coming weeks for photos, blogs and updates from the team downunder.