See You in 100 Years

(C) Duke Marsh in Clarksville, Indiana.

It was real

Venus traveled along the surface of the sun yesterday. The planet may have looked a tad differently than you expected or imagined. Unless you always thought Venus was a small black dot, than you were spot on. No matter the size or color: the Transit of Venus won’t happen again until 2117. The phenomena has always been a must-see for astronomers around the globe. But, astronomers aren’t the only ones appreciative of the once in a life time site.

Why did it happen?

When Venus passes between the Earth and the sun it travels as a small black dot along the surface.The event is so rare because the planet’s orbit is tilted 3.4 degrees relative to the Earth’s orbit. Every 105 years the Transit of Venus occurs twice, eight years apart.Only four transits occur every 243 years, according to the LA Times.Venus orbits the sun every 226 days verses the Earth’s 365 day cycle and so the two planets pass each other quite regularly. The orbit’s tilt on the plane is why the alignment is so rare.  The last Transit of Venus was in 2004 but it wasn’t visible in the West. The transit on June 5th  lasted over 6 hours. Venus isn’t the only planet to cross the sun. A transit, or passage, of any planet across the sun’s surface is rare. From Earth only Mercury and Venus can be seen crossing the sun, according to the NASA Observer’s Handbook.


The Transit of Venus has long been a tool to measure to study the universe. In 1875 astronomers, including amateur citizen scientists!, photographed and observed the transit in an effort measure the distance between the Earth and the sun. The photographs went through rigorous computational work and analysis. However, the results weren’t accurate. The weather, clouds, time of day and even the angle one was standing made a difference in the calculations. The article, The Astronomers’ Work: Results to Science of the Transit of Venus, from July 29th 1875, updated the results of the December Transit of Venus in 1874.

“that is, there was163 pictures taken in the northern, and 187 in the southern hemisphere, making a total of 350. On the whole this is tolerably satisfactory result…although some of the contact observations give satisfactory values of the parallax, others give values which are evidently quite erroueous.”

What now?

If you missed the Transit of Venus you don’t need a scientific miracle to see it again in 105 years. A wonderful Citizen Science project, Astronomers Without Borders, is revived the classic procedure photographing the phenomena to the 21st century. Through the app users could log the Transit of Venus from their spot on Earth. Astronomers without Borders also provided real time analysis of the data.Stay tuned for updates and information from the Citizen Science Project. The Guardian live blogged the whole Transit of Venus here. There is still time to participate in Citizen Science. Submit your photos to different citizen science sites, check Scientific American for a list. Your work can live on for the next century.

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