BellaOnline Forums Education Astronomy Memories of the Transit of Venus

The last transit of Venus took place on June 6, 2012. Only the very last bit of it would be visible from where I was, as the Sun rose. Since this was at 51 degrees of latitude, the Sun was going to rise quite early at that time of year.

Three of us found our way to the riverside equipped with eclipse glasses and a pair of solar binoculars. All in vain. Thick cloud cover insured that at best there was an occasional filtered glimpse of the Sun, but certainly not enough to see a black dot crossing its face.

However the "Our Solar System" category in the 2012 Astronomy Photographer of the Year was won by Chris Warren who managed to capture one moody frame of the cloudbound transit of Venus from near Greenwich, England.

There is probably someone somewhere alive today who will be around when the next transit of Venus occurs, but that won't happen for another hundred years.

I can't claim that the dismal 2012 transit viewed from England was anything like the worst experience of a transit of Venus. Here is the story of French astronomer Guillaume LeGentil who - poor fellow - twice came close to observing a transit of Venus, but was thwarted both times.

That is a gorgeous picture.

We actually know which transit of Venus was the first to be observed - it was in 1639. Only two people saw this transit of Venus - Jeremiah Horrocks and William Crabtree in the north of England.

Horrocks was a brilliant young mathematician and astronomer. He used what little data he got from the transit - bad weather interfered - to estimate the distance from the Earth to the Sun. He got a ridiculously large figure. Which, in fact, was only 2/3 of the actual distance.

Most of the details of Horrock's life are unknown, but he was only 22 when he died.

How big is the Solar System? 18th century astronomers tried to find out by sending expeditions around the world to measure a transit of Venus. One of these was Captain Cook's voyage to Tahiti. He went under the auspices of the Royal Society, but he carried secret orders from the British government.

Transit of Venus - Captain Cook 1769

On June 8, 2004 millions of people witnessed an event that no one still alive had ever seen: a transit of Venus. Another occurred in June 2012, but it was the last for over a hundred years. What is a transit of Venus? How did it help to work out out the size of the Solar System?

Transit of Venus - Measuring the Solar System

Diagram showing how a transit of Venus lets us calculate our distance from the Sun

This special sunrise analemma is one of my favorite pictures.

You can get an analemma by photographing the Sun from the same place at the same time of day during all or part of a year. This one was carried out in the city of Baku, Azerbaijan from April 2 to September 16 in 2012, so it's almost half a year. Besides being a beautiful photograph, you can see the position of the Sun changing as it gets higher and higher above its equinox position.

But look at the top of the analemma where there are two Suns at about the same height. The one on the right has a tiny black dot on it. You have to enlarge the picture and look closely to see it. That is Venus transiting the Sun.

Image Credit & Copyright: Tunç Tezel (TWAN)

This is a double transit from Astrophotographer Thierry Legault who is known for the amazing shots that he gets. He manages things that require considerable research, preparation and timing. Here he's captured 9 images of Hubble Space Telescope transiting along with Venus. The telescope is tiny, so its progress has been circled. Legault had less than 1 second to image Hubble.