Health

How To (Safely) Watch This Week's Solar Eclipse

On the morning of March 9, there will be a total solar eclipse. From Australia, we’ll only get to see a partial eclipse — but the sight should still be highly arresting — especially if you live in Darwin or Cairns. Here’s how to watch this celestial event without damaging your eyes.

Photo: Exploratorium

Unlike a lunar eclipse, solar eclipses are never safe to look at and you will need to use safe solar viewing techniques as outlined below. The March 9 Solar Eclipse is set to occur in the mid-morning on a Wednesday, which means you’ll probably be stuck at work without any special equipment. However, even a simple pinhole or leaf shadows will allow you to see the eclipse safely.

Viewers will see between 50% (Darwin) and 0.6% (Rockhampton) of the Sun covered by the Moon, with North Australia getting the best views. The eclipse will begin between 9:07am and 10.55am depending on your location. (Click here for a full list of start times.) You will need a flat, unobstructed horizon to see the eclipse at its best.

Dos and Don’ts

Do NOT look directly at the Sun! Do not use so-called filters. Over exposed film and smoked glass 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).

A pair of specialist solar eclipse glasses [Image: “>Shutterstock]

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. At no time is it safe to view the eclipse with the unaided eye.

DIY

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 the image in shadow. I use the longest available postpac postal tube, with alfoil over the top (and the pinhole in the alfoil), and a 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 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 — even a couple of seconds is dangerous so don’t even “take a peek”. Here are the regions in Australia that will boast the best views.

City Eclipse Start Mid Eclipse Eclipse End % Sun Covered
Alice Springs (ACST) 9.29AM 10.16AM 11.06AM 11%
Broome (AWST) 7.32AM 8.32AM 9.37AM 37%
Cairns (AEST) 10:12AM 11:12AM 12:15pm 18%
Darwin (ACST) 9.07AM 10.17AM 11.34AM 50%
Rockhampton (AEST) 10.55AM 11.17AM 11.38AM 0.6%
Perth (AWST) 8.06AM 8:26AM 8.47AM 1%

Ian Musgrave is Senior lecturer in Pharmacology at University of Adelaide. He does not work for, consult to, own shares in or receive funding from any company or organisation that would benefit from this article, and has no relevant affiliations.

The ConversationThis article was originally published on The Conversation.


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