Shadow on the Sun 

Rare Venus event 
puts it between Earth, Sun 

Very few among those alive have seen a transit of Venus, a rare astronomical event which occurred on Dec. 6, 1882 last time. A transit of Venus occurs when the planet comes directly between the Earth and the sun. Venus is then visible as a small beauty mark on the face of the Sun. Since 1882, a long wait is over. On June 8, 2004 Venus will once again transit the Sun. 
Transits of Venus crop up in pairs eight years apart, but more than a century separates any two pairs. The transit this June will be followed by another in 2012. But the next pair will be in 2117 and 2125. 

History: 

1631 and 1639 
Johannes Kepler predicted the first transit of Venus in 1631. No one saw it. The Thirty Year's War, cloudy weather, and the short duration of the transit made observing impossible. 
The next transit in 1639 was only viewed by two astronomers in England. Jeremiah Horrocks calculated the transit and employed his friend William Crabtree to observe from a neighboring city. 

1761 and 1769 
Astronomers from European countries mounted great expeditions to the far corners of the globe — Siberia, India, Madagascar, South Africa and the South Pacific — to see the transits of the 18th century. One of the greatest adventures to see the transit of 1769 was led by Captain James Cook, who took his crew to the island of Tahiti. From Point Venus, Cook and company had perfect weather and a nice stay in a tropical paradise. 

1874 and 1882 
After 105 years, astronomers eagerly awaited the transit of 1874. Russia, Britain, France, Germany, Italy, Holland, and America funded 62 expeditions to see it. Astronomers used a new invention: the camera. The transit of 1882 was especially viewable from the United States. And not just astronomers were geared up for the event. This was one of the most talked about cultural events of the year. This transit was continually reported in newspapers and sales for smoked glass (the “safer” method of observing the sun in 1882) skyrocketed. The New York Times reported: “This is the first time within the memory of man that the unlearned common people have been permitted to observe a transit.”

Safety in 2004:
Looking at the sun will damage your eyes, so the easiest and cheapest way to observe it safely is by looking through eclipse shades. Don't wait for June 8 to see Venus. You can watch it blazing in the western sky after sunset, brighter than any other star-like object.

(Dean Regas is the Outreach Astronomer at the Cincinnati Observatory Center.)