The 19 month dark star cycle

Photo of Venus at inferior conjunction  

This is a telescopic photo of the planet Venus taken on October 31st by Henry Mendt of Maracaibo, Venezuela, and found on Spaceweather.com.   

Right now, Venus is passing almost directly between Earth and the sun, an event astronomers call an "inferior conjunction." It happens every 19 months, more or less. The next such inferior conjunction between Earth and Venus will be in the first week of June, 2012, about nineteen months from now. 

Although Venus orbits the sun in 225 days, the earth is also moving in her orbit around the sun. Venus is always playing 'catch-up' with the earth, which is why it takes more than 19 months for Venus to "transit the sun" from an earth-based point of view. It is a *dark transit* because Venus is presenting its nighttime side to earth viewers. A presentation at a 2007 meeting of the Division for Planetary Sciences, American Astronomical Society, diagrammed the correlations between this cycle of Venus, sunspot activity, and major disease outbreaks on Earth. You can find that information here 

When the daylight side of Venus faces toward earth, it is second only to  the moon in brightness. Depending upon the location of Venus to the sun  in its bright-side part of the cycle, Venus is known as either the  'evening star' or the 'morning star,' because it is brightest just after  sunset in the early evening, or just before dawn in the morning.  Now,  during its transit of the sun, Venus is a dark star. 

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Tom Fox
Louisville, Kentucky