The planet Venus will put on its most spectacular performance of the century this spring, culminating on June 8, 2004 with its transit across the face of the Sun. The last time Venus made this transit was on December 6, 1882. A transit of Venus to the Sun can only happen within a day or two on either side of June 7 or December 8, and the phenomena never happened at all during the 20th century!

The entire Venus cycle takes 19 months and is less apt to be retrograde than any other planet. It spends only six weeks in backward motion every 19 months. And for a transit over the Sun itself to take place, that backward motion must happen in June and December when the Earth crosses the Venus line of nodes. During a transit Venus must be at its inferior conjunction to the Sun, meaning the midpoint of the retrograde period. These Venus transits sometimes come in pairs, eight years apart. We are fortunate to be alive during such a time, and if you somehow miss this year's transit, you may still be around to witness the next one due on June 6, 2012.

Venus has been visible as an evening star since the fall of 2003, moving closer and closer to the Earth. It reaches greatest elongation east of the Sun, 46 degrees, on March 29, the same day that Mercury is at greatest elongation east at 19 degrees. Venus is at its highest and brightest this year, reaching greatest brilliancy in early May at 27 N 49 declination, nearly as high as it ever can at midnorthern latitudes. Venus also holds hands with Mars at high declination in late April and early May before Venus stations on May 18 and turns retrograde for six weeks. Also worth noting will be the Moon's occultation with Venus on March 24 and again on April 22 and 23rd, only two days before Venus' closest approach to Mars. And that is not the end of the celestial fireworks as the Moon will once more conjunct Venus on May 21 with both only 25 degrees from the Sun which will make viewing more difficult.

The Venus extravaganza ends on June 8 when it catches up with the Sun and astronomers around the world will experience the transit they will have been waiting for with such expectation. Unfortunately only the East coast of the United States will be able to view the transit, which will already be in progress at sunrise. The Sun will rise in Boston about 5:30 a.m. daylight time when Venus will already have moved more than halfway across the Sun's face. Central and western parts of the country will not be able to see the transit. The Sun that day should be viewed only with an appropriate filter as watching it with the naked eye could result in serious eye damage and even blindness. And for those who miss it, the good news is that the whole event will be repeated on June 6, 2012.

© 2007 Frances C. McEvoy
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