Venus to "Eclipse" Sun for First Time in 122 Years (Forwarded)

Sky & Telescope
Cambridge, Massachusetts

Contacts:
J. Kelly Beatty, Executive Editor
617-864-7360 x143,

Alan MacRobert, Senior Editor
617-864-7360 x151,

Press Release: May 24, 2004

Venus to "Eclipse" Sun for First Time in 122 Years

On Tuesday, June 8th, the planet Venus will glide directly across the face of
the Sun. No one alive today has seen Venus "transit" the Sun -- it last happened
in 1882 -- and astronomers around the world are eagerly awaiting this rare
event. Only one other transit of Venus will occur this century, eight years from
now on June 6, 2012.

Think of a transit as a miniature eclipse of the Sun. During a total solar
eclipse, the Moon completely blocks the Sun's disk for just a few minutes. But
even though Venus is much larger than the Moon, it's also about 100 times
farther away, so it can cover only a fraction of the solar disk. As Venus makes
its long-awaited crossing, it will appear as a perfectly round black dot slowly
moving across the Sun's face. The most interesting aspects of this 6-hour-long
event will occur when Venus enters and exits the outer edge of the solar disk,
each passage taking about 20 minutes to complete. For example, as it starts to
leave the Sun the planet's silhouette may look pear-shaped, creating what's
called the "black-drop effect."

For observers in eastern and central North America, the Sun rises on June 8th
with the transit already well under way. The entire event will be visible from
Europe, central/eastern Africa, the Middle East, and Asia (except the Far East).
The table below
[http://skyandtelescope.com/aboutsky/...le_1259_1.asp] lists
representative North American cities for which the transit will be in progress
at sunrise, grouped by time zone. Transit times for cities in Europe, Africa,
the Middle East, and Asia are also available at
http://skyandtelescope.com/observing...cle_1021_3.asp

Warning: The Sun is dangerous to look at directly without a safe solar filter.
Staring at it can cause serious eye injury and even blindness.

Fortunately, there are many easy ways to watch the transit safely. If you have
keen vision, Venus should appear just large enough to be barely visible as a
tiny black dot as it crosses the Sun. But when looking at the Sun you must use a
safe solar filter, such as a #13 or #14 welder's glass or special "eclipse
glasses" designed for solar viewing. Filters that are not safe, though sometimes
recommended in error, include smoked glass, stacked sunglasses, metallized candy
wrappers, and compact discs. While these will darken the Sun, they may still
transmit enough invisible infrared radiation to damage your eyes.

Binoculars or telescopes can be used to view the transit, even if they are not
equipped with a safe solar filter. Do not look directly into the eyepiece or the
telescope's finder, but instead place a white card behind the eyepiece and
project the Sun's image onto it. (The small, dark-glass disks that screw into
the eyepieces of some older scopes are not safe and should be discarded. The
Sun's light and heat, concentrated by the telescope, may shatter them suddenly.)

A guide to June's transit of Venus and viewing the Sun safely appears in the
May/June issue of Night Sky magazine, now available on newsstands. To obtain a
PDF of this article via e-mail, media representatives should contact Marcy L.
Dill (617-864-7360 x143; ). More detailed articles,
exploring the historical significance of transits and how to photograph them,
appear in the February, May, and June issues of Sky & Telescope magazine.

For more tips on how to view the Sun safely, see "Safe Solar Observing",
http://skyandtelescope.com/observing...cle_1260_1.asp

Related Articles:

* The Transit of Venus: Where to See It
http://skyandtelescope.com/observing...cle_1021_1.asp
* Safe Solar Observing
http://skyandtelescope.com/observing...cle_1260_1.asp
* Solar Filter Safety
http://skyandtelescope.com/observing...ticle_94_1.asp
* Solar Filter Suppliers
http://skyandtelescope.com/observing...icle_101_1.asp
* Photographing the Transit of Venus
http://skyandtelescope.com/howto/ima...cle_1255_1.asp
* Reanimating the 1882 Transit of Venus
http://skyandtelescope.com/observing...cle_1187_1.asp