Eclipse-watching – December 4th 2002
Claire Flanagan (Dr) Director, Johannesburg Planetarium
All of South Africa will experience a partial eclipse of the Sun from around
7:30am to 9:30am on December 4th. In addition, parts of the Northern Limpopo
Province will experience up to 87 seconds of a spectacular total eclipse.
Since (a) there will be massive media coverage of this event, and (b) Many
learners saw or knew of the partial eclipse of June 2001, we urge educators to
make use of this educational opportunity and to encourage learners to watch the
eclipse safely.
To this end, the Planetarium, in collaboration with the College of Education
at Wits University, will be making sets of worksheets available to all
interested parties, from mid-November.
SAFE ECLIPSE VIEWING:
Sunlight causes eye-damage if one either stares at the Sun for a long time
(for more than a few seconds), or if one looks at the Sun for even a fraction of
a second through either a camera, binoculars, or a telescope.
Normally, the intense light of the Sun discourages one from staring at the
Sun. However, the heat (infrared) in sunlight also causes damage –burns to the
retina of the eye, which in turn cause blind spots.
IT IS THUS EXTREMELY DANGEROUS TO LOOK AT THE SUN USING ORDINARY
SUNGLASSES – these do not protect the eyes from the Sun’s heat.
The only safe way to watch the Sun (including during a partial eclipse of the
Sun) is through special eclipse viewers that are designed for this purpose.
These viewers are normally made of cardboard. In the eyepieces they have strips
of either aluminised Mylar, or a type of black polymer, that is specifically
designed to block at least 99.997% of the light and 99.5% of the heat from the
Sun. These viewers should be used for watching all partial phases of an eclipse.
It is not safe to use a camera to photograph the Sun, even while wearing eclipse
viewers.
Various indirect (i.e. safe) ways of watching the Sun during the eclipse, by
projection of the Sun’s image onto paper, are also available. However, if not
done correctly such methods can be dangerous. An additional problem is that
learners will still want to watch the Sun changing shape directly, and that the
best and simplest way to do this safely is through the eclipse viewers.
We at the Planetarium thus recommend that learners be provided with eclipse
viewers that meet the international standards designed for solar viewing. We
also note that since the viewers can be shared among a group of learners, and
they are cheap, this should not involve unreasonable expense, especially bearing
in mind the value of good eyesight to the future generation of adults.
Should learners not be gathered together on December 4th between 7:30am and
9:30am, we recommend that at least one viewer per family group be provided.
E-mail flanaganc@planet.wits.ac.za
Web-site www.wits.ac.za/planetarium
Eclipse Africa is manufacturing special cardboard Eclipse viewers to look at
the Sun during a partial or total Solar Eclipse
1 to 1000 R 3,55 excluding VAT & postage
1001 to 2000 R 3.45 excluding VAT & postage
2001 to 5000 R 3,35 excluding VAT & postage
5001 to 10000 R 3,20 excluding VAT & postage
10001 to 20000 R 3,05 excluding VAT & postage
20000 to 50000 R 2,85 excluding VAT & postage
50001 to 100000 R 2,60 excluding VAT & postage
100001 + R 2.35 excluding VAT & postage
E-mail: eclipseafrica@iafrica.com
Website: www.eclipseafrica.co.za
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