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Tuesday, April 11, 2023


Hybrid Solar Eclipse, April 20, 2023

Partial Eclipse as seen from Adelaide at maximum eclipse, 13:29 ACST. Simulated in Stellarium.Partial Eclipse as seen from Darwin at maximum eclipse, 13:52 ACST.
Partial Eclipse as seen from Brisbane at maximum eclipse, 14:45 AEST. Partial Eclipse as seen from Perth at maximum eclipse, 11:21 am AWST.

On 20th April the Sun will be eclipsed at the very edge of Australia, the path of totality will pass over the northwest cape in WA, being visible from Exmouth and Learmonth. If you haven’t already booked your campsite or hotel, it is too late, it was all booked out months ago. This is a hybrid eclipse, which annular in some parts of its path and total in others.

Partial eclipse as seen from Grealdton WA at maximum eclipse (11:22 am AWST).

The rest of Australia sees a partial eclipse, with WA having the best view, Broome and Geraldton see >80% of the Sun covered: Darwin 80%, Perth 71%, Cairns 50%, Townsville 36% and Adelaide 21%. the partial eclipse begins around 10 am local time WA, 12 pm central states and 1 pm Eastern states (see table below for detailed times and eclipse coverage for selected cities, for places in between these cities the coverage will be about midway and the times similar).

A map showing eclipse times in Universal Time is here.

Do NOT look directly at the Sun! Do not use so called filters. Over exposed film, smoked glass, CD's, chip packets etc. used as filters are NOT, repeat NOT safe. Only special solar-rated viewing spectacles from astronomical suppliers should be used (for one example see here), they may cost a bit, but your eyesight is without price. Never use eyepiece filters for telescopes. These can crack at inopportune times and destroy your eyesight. In the annular eclipse path, as there is always some of the solar disk visible, at no time is it safe to view the eclipse with the unaided eye.

The easiest and cheapest way to observe this event is by making a pinhole in a stiff square of cardboard and projecting the image of the Sun onto a flat surface. You are basically making a simple pinhole camera, which will reveal the changes to the Suns outline quite satisfactorily. A card with a 1 mm hole should be projected onto a surface (eg white paper, or a white wall) about 20 cm away, a 5 mm hole should be projected onto a surface 1 to 1.5 meters away.

You need to create a reasonable sized image, so you need a fair distance between the pinhole and the surface you project the image on. This will mean the image is going to be fairly dim, so you also need some sort of sun shield to keep in image in shadow. I use the longest available postpac postal tube, with alfoil over the top (and the pinhole in the alfoil), and wide ring of stiff cardboard to ensure that the image of the sun is projected into a dark area. This link will show you several methods to make pinhole projection systems.

You are not limited to holes in cardboard, I have used Water crackers and colanders and gaps between leaves as projection systems. 

You can also use binocular and telescopic projection systems. This link will show you how to make safe solar viewing and telescope projection systems. Here is my step by step guide to making a binocular projection system, and a guide to aiming your binoculars or telescope when you can't actually look at the Sun. And this is the projection system I use with my refractor telescope.

Remember, do NOT look directly at the Sun, as irreparable eye damage or blindness can occur (see this video for a graphic demonstration).

City Eclipse Start Mid Eclipse Eclipse End % Sun covered
Adelaide (ACST) 12:22 13:29 14:34 21
Alice Springs (ACST) 12:13 13:37 15:01 48
Brisbane (AEST) 13:44 14:45 15:42 16
Broome (AWST) 10:22 am 11:53 am 13:27 89
Cairns (AEST) 13:25 14:49 16:05 42
Canberra (AEST) 13:28 14:21 15:11 10
Darwin (ACST) 12:18 13:52 15:25 81
Geraldton (AWST) 09:59 am 11:22 am 12:50 82
Hobart (AEST) 13:25 14:06 14:47 5
Melbourne (AEST) 13:15 14:09 15:01 11
Perth (AWST) 10:00 am 11:21 am 12:47 am 71
Sydney (AEST) 13:37 14:29 15:19 10
Townsville (AEST) 13:27 14:47 16:00 36

 Cloud cover predictions can be found at SkippySky.

Here is the near-real time satellite view of the clouds (day and night) http://satview.bom.gov.au/


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