What’s up? The solar eclipse, 20 April 2023
The Sun seen totally eclipsed by the Moon in 2012 in Cairns, QLD, with the solar corona clearly visible. Photo: Rob Hollow.
The celestial highlight of the year will be an eclipse of the Sun, which will be visible in Western Australia on Thursday, 20 April. The Moon will pass in front of the Sun and briefly cover it up.
There are different types of solar eclipses and this one is the rarest. It will be an annular-total eclipse (also known as a hybrid eclipse).
An annular eclipse is where a narrow bright ring forms around the Moon when it covers the Sun. This is often called the ‘ring of fire’. In a total eclipse the Moon appears to fully block the Sun so that only the solar corona (the ‘crown’ of light that is emitted by the Sun) is visible.
This eclipse will start as an annular eclipse, then become a total eclipse, before returning again to annular. This hybrid process should take just more than a minute.
Viewing the eclipse
The only place in Australia where the hybrid eclipse is visible in North West Cape,with Exmouth close to the path of totality. At Exmouth, the eclipse is due to take place at 11:29am and the weather outlook says clear skies are likely. However, access on the day will be challenging and accommodation in the region is already booked out.
For those elsewhere the eclipse will appear as a partial eclipse, where part of the Sun is blocked by the Moon. Those in Carnarvon will experience a 97% eclipse (where the Moon is covering 97% of the Sun), Geraldton 82% and Perth 71%. The last total eclipse visible in Australia was in Cairns in 2012.
The Moon will appear to touch the Sun (the beginning of the eclipse) just after 10am, with totality at 11:29am. The eclipse ends around 1:00pm. The Astronomical Society of Australia’s Eclipse website includes details of where to view it, what to expect and how to view the event safely.
Another useful site showing times and visibility for Western Australia is Ningaloo Eclipse. It allows you to enter your location for detailed timings and percentage of eclipse.
A total, annular or hybrid eclipse is an unforgettable experience. This year’s event will generate enormous interest in the region with an influx of tourists on land and on cruise ships off the coast of Ningaloo.
View of a partially eclipsed Sun as it rose during the 2012 total eclipse in Cairns, QLD. Photo by Rob Hollow.
Eclipse safety
Please do not try and observe the partially or totally eclipsed Sun directly. Specialist equipment is needed. Smoked glass, welding glass and neutral density photographic filters should not be used. Eclipse glasses that use mylar filters are safe to use provided you check beforehand that there are no holes or pin pricks. Another safe way is the projection method, details can be found on the Astronomical Society of Australia Eclipse site. More details will become available on the CSIRO website too.
Rob Hollow, Education Manager, CSIRO