Viewing the Eclipse

WARNING
DO NOT LOOK DIRECTLY AT THE SUN WITHOUT PROPER EYE PROTECTION
DO NOT LOOK AT THE SUN THROUGH BINOCULARS, TELESCOPE OR CAMERA
DO NOT "STARE" (LOOK FOR MORE THAN A FEW SECONDS) AT THE SUN

by Claire Flanagan (claire@astroclaire.co.za / www.moonshadowmix.co.za).
Video (2.5min) on watching a solar eclipse safely (with or without eclipse viewers) on YouTube.

Eclipse Viewers

GlassesUnknown (5K) "Spectacle" viewer.
ViewersHandheldAa (17K) Handheld viewers.


Eclipse viewers are made according to international safety standards - they must block 99.997% of visible and UV radiation, and 97% of the infrared (ISO 12312-2). They are safe for direct viewing of the Sun, and relatively cheap (under US50c each, excluding shipping, if bought in bulk).

They can easily be shared - people should be looking for only a few seconds at a time.

Current suppliers include:
It is also possible to buy filter material, and print+assemble your own (in bulk) - see this page.

Alternative Eye Protection

FiveRosesAa (30K) A double layer of Five Roses teabag foil wrapper.
SpaceBlanketAa (27K) Three layers of "space blanket", used by first-aiders.


Shade 13 or 14 welding glass is quality-controlled to meet the required safety standards for eclipse viewing.

Ordinary sunglasses are not suitable for eclipse-viewing - they block only about half the sunlight (eclipse-viewers block 99.997%).

Some commonly available foil materials have filtering properties similar to those of recommended solar filter material - they block visible, UV and infrared. Transmission measurements of some that I made while at the Johannesburg Planetarium are available here.
Obviously, these materials are not the ideal substitute for properly-regulated solar filter material. However, they are much more widely available.

A suitable material would:
In South Africa, suitable locally-available materials are: Anyone locating similar useful material in other countries should please contact us so we can add yours to the list.

Pinhole Projection under Trees

PinholeUneclipsed 002Aa (16K) Uneclipsed Sun.
Eclipse2006PinholeProjectionAa (16K) Eclipsed Sun.


Look on any sunny day in the shade under a tree for circles of light - these are "pinhole projected" Sun images. You need the right kind of tree - trees with rounder leaves work better. During an eclipse, the circles will change into images of the eclipsed Sun. This is easier to see if you put a sheet of white paper on the ground.

This is by far the safest way to look at the eclipse - you're not looking directly at the Sun - and it's very impressive - kids love it.

Other Pinhole Projectors

PinholeProjection (6K)
Pinhole Projection.
Eclipse2013Nov3JhbPlanetarium_ProjectingPinholeEclipseArtAa (17K) Write your name in "pinholes" - make pinhole eclipse art.


Make a small hole, with the end of a sharp pencil, in a sheet of paper. Look for the image of the Sun projected through this "pinhole" onto a second sheet of paper below.
This is simple and safe, but not very satisfactory - the image is small compared to those seen under trees - because the "pinhole" is so much closer to the projected image.

However, it is: You can make an improved pinhole projector using a long box - see instructions from The Exploratorium.
spiralAa (7K) Pinhole projection art from By Sean B Palmer, UK
shootingstarAa (13K) Pinhole-projection art from Sirius Travel - specialists in eclipse and adventure travel


Magnified Projection


MAKE VERY SURE NO-ONE LOOKS THROUGH THE TELESCOPE AT THE SUN.
THIS WOULD CAUSE PERMANENT SEVERE EYE-DAMAGE.

Eclipse2013Nov3JhbPlanetarium_ScopeProjectionAa (30K) Eyepiece end close to board so people can't look through it.
Eclipse2013Nov3JhbPlanetarium_ScopeProjectionBa (11K)

ProjectionSpotterAa (28K) The wire is to stop people from looking through the eyepiece.
ProjectionBoxAa (25K) Half a pair of binoculars in a box, to stop people looking through the eyepiece at the Sun.


MAKE VERY SURE NO-ONE LOOKS THROUGH THE TELESCOPE AT THE SUN.
THIS WOULD CAUSE PERMANENT SEVERE EYE-DAMAGE.


A small telescope, or binoculars, will project a bright magnified image onto a piece of white paper.

It is essential that no-one looks through the eyepiece - this would likely blind them - aim the telescope by pointing it towards the Sun, and watching the shadow of the tube on the projection paper - move the telescope until the shadow is smallest (i.e. the Sun is shining directly along the tube).

The cardboard sheet on the front end of the telescope is to create a dark patch of shade, which makes it easier to see the image.

This kind of setup must be kept under constant supervision, to make sure no-one looks through the eyepiece at the Sun.

Looking through a Telescope fitted with a Solar Filter

TelescopeLabelledAa (11K)
TelescopeLabelledCutawayAa (14K)

Some astronomers with backyard telescopes will install sun-filters and look through the telescope directly at the Sun. Some will take these telescopes to schools and public places, to share the view.

Before you look through one of these telescopes, make sure it is set up safely and professionally:
IF A SOLAR FILTER BREAKS OR FALLS OF WHILE THE TELESCOPE IS POINTED AT THE SUN,
THE PERSON LOOKING THROUGH IT
WILL SUFFER SERIOUS AND PERMANENT EYE-DAMAGE..

Children and Eclipses

SharingViewers01Aa (17K) Viewers can be shared ...
SharingViewers02Aa (13K) ... under controlled conditions!


Children are more susceptible to eye-damage from UV radiation than adults; although UV is more of a long-term-exposure worry than a (brief look) eclipse problem, they should if possible use proper eclipse-viewers for eclipse-viewing.

Children (and many adults) cannot hear the message "if you do that it will severely injure you". Do not just warn them not to look at the eclipse with binoculars - lock the binoculars away. Do the same with telescopes, and with cameras that involve view-finders.

Children have fantastic recall of the message "if you do that it will severely injure you" in certain circumstances - if you prevent them from watching the eclipse, and they find out later that millions of people watched without being harmed, they may justifiably be less likely to pay attention when we warn them about real dangers such as drug-abuse. Make sure they watch safely, but please let them watch.

Realistically, the view of the Sun through eclipse viewers is tiny, the eclipse progresses slowly, and they can get bored. Organise related activities such as pinhole-projection art, and encourage them to photograph the art with their phones.

Photographing the Eclipse

name_projAa (13K)
name_projCa (3K)

It is perfectly safe to photograph projected images of the Sun.

It is perfectly safe to photograph the actual Sun with a camera that does not involve you looking through a viewfinder - you can safely take photographs with an ordinary cellphone camera. Put some filter material (e.g. an eclipse viewer) in front of the camera, or you may damage the camera. Don't look at the Sun while aiming the camera - look at the image on the phone screen.

Expect the results to be disappointing - the Sun is actually very small. You will get a better result with a zoomable camera (including video) - again, don't look through the viewfinder, and don't look at the Sun while aiming.

It's actually much more fun to photograph pinhole-projected eclipsed Suns - either under a tree or created with pinhole-projection art.

Serious photographers should google "eclipse photography" for professional advice; you will need a filter for your camera.



Facts about Eclipse Eye Damage

GrapeStuartLowe (8K)
A grape (representing your eye) burnt after being held at the telescope eyepiece - watch on Stuart Lowe's astronomy blog.
PigsEyeMarkThompsonAa (15K) A (dead) pig's eye looking through a telescope - watch on Mark Thompson's YouTube channel.


The generally-accepted facts about eclipse eye safety are: * Note: "unaided" in this context means "without using a telescope or binoculars or similar"; "protected" means "protected with eclipse-viewers (or similar)"

The above information was extracted from ISO 12312-2 (safety standards for "Filters for direct observation of the sun"), available (at a price) from www.iso.org.
An (older) open-access article by eclipse eye-safety expert Prof B. Ralph Chou, published by NASA, is available here.



Questions and comments can be sent to Claire Flanagan.