Rare Venus Transit Across the Sun by Dennis Mammana on Creators.com

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Rare Venus Transit Across the Sun

Early evening sky watchers may have noticed that the brilliant planet Venus is now appearing lower in the dusk sky each evening; this is nothing to be concerned about. It happens because Venus is orbiting the sun and, within only a week or so, it will cross over to the opposite side of the sun and will soon become visible as an early morning "star."

What we don't usually see is the actual crossover itself. On June 5, however, we will.

Astronomers know the phenomenon as a "transit of Venus," and it's one of the rarest celestial events you'll ever see. In fact, if you miss this one, you'll have to wait 105 years for your next chance.

During a transit, a properly protected eye can see a tiny black dot slowly crossing the face of the sun. While it will be just possible to spot Venus' silhouette without optical aid as it crosses the Sun—the planet will appear only 1/32 of the sun's diameter—you'll find that properly filtered binoculars or a telescope will produce a more exciting view.

Much like viewing an eclipse of the sun, observing a transit with safety is extremely important. Never view the sun with the naked eye, sunglasses, double thickness of darkened film, smoked glass or other homemade filters. While these may seem to reduce the sun's glare, they will not cut the invisible radiation (infrared and ultraviolet) that can burn your eyes without you even being aware. To learn more about safely viewing and photographing the sun, be sure to check out Fred Espenak's terrific website at: mreclipse.com/MrEclipse.html#Sun.

Transits of Venus occur in pairs after a wait of more than a century. This will be the second of this pair (the first occurred in 2004 and was not visible in the U.S.); the next pair won't occur until December 11, 2117 and December 8, 2125.

The rarity of this event means that all astronomers' eyes will be aimed in this direction on June 5.

One of the first such transits to be studied carefully occurred on June 3, 1769, when the famous British navigator Captain James Cook observed a transit from the island of Tahiti — at a location still known as Point Venus. His work that day helped astronomers determine the dimensions of the solar system, and navigators calculate their exact longitude.

Next week's transit begins officially on June 5 at 6:09 p.m. EDT (3:09 p.m. PDT), when sharp-eyed observers may spot the silhouetted edge of Venus just entering in front of the solar disk. By 6:27 p.m. EDT (3:27 p.m. PDT), the planet's entire disk will become visible. The sun will have set for all of the continental U.S. by the time the transit ends. Those living on Pacific islands, Asia and east Africa will enjoy the rest of the show.

The transit times I've provided on the illustration are in Universal Time (UT), which is essentially that of Greenwich, England, and you'll need to convert to your own local time. Eastern Daylight Time is four hours behind UT, CDT is five hours behind, MDT is six hours behind, and PDT is seven hours behind Universal Time, so a simple subtraction is all you'll need to do.

For example, 22:09 minus four equals 18:09 (6:09 p.m. EDT). If you feel you're "arithmetically-challenged," use this table from the U.S. Naval Observatory: tycho.usno.navy.mil/zones3.html.

Whenever the transit occurs where you live, I cannot emphasize enough safe viewing of the transit. Looking at the sun without a proper solar filter — even for an instant — can cause permanent eye damage or blindness.

The best and safest way to view this rare event is to contact a local planetarium, observatory or amateur astronomy club to learn when and where they will have telescopes set up (astronomyclubs.com). To learn more about where and how to view the transit safely, visit transitofvenus.org and eclipse.gsfc.nasa.gov/OH/transit12.html.

Be safe... and enjoy the sky show!

Visit Dennis Mammana at www.dennismammana.com. To read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.