June 2012: San Francisco and Transit of Venus

French version available here (Version française disponible ici) : http://surlarouteagainfr.wordpress.com/2012/07/11/transit-de-venus-du-5-juin-2012/


“The first man who will live 1,000 years has probably already been born”

Aubrey David Nicholas Jasper de Grey

“I don’t want to live 1,000 years, that sounds boring!”



On June 5th 2012 (or June 6th if you were in Europe), a very rare astronomical event was to be seen: a transit of Venus. In case you are wondering what it is: a transit of Venus is when the planet Venus passes directly in front of the Sun as seen from the Earth, becoming visible as a tiny black disc slowly moving across the face of the Sun.

Because the next one would not occur until 2117 (and I have no intention to live past 133 years…), I decided to get the maximum out of this one and I planned a trip to the West coast for the observation. A good occasion also to visit some friends in California and enjoy the wonders of the Golden State.

So, it’s from the Pacific coastline, some 50 miles south of San Francisco that I would go to witness this rendez-vous between Venus and the Sun. On june 5th/6th, for the 68th anniversary of the invasion of Normandy, I had my own rendez-vous with the Sun and Venus on a small parking, wedged between the mythical highway 1 and the Pacific ocean, facing the tallest lighthouse on the West Coast (Pigeon Point lighthouse). By the time the Sun was setting on the Pacific, I had spent 8 amazing hours on this parking and I was thinking about the fact that 20 minutes later the Sun would rise on Lyon (in France) for the beginning of a very important day: my nephews first birthday!

Here is the story of these 8 legendary hours and everything that led to it…

A little bit of history…


Looking up at the sky, there is no way that you’ve never been amazed by the beauty of a starry night sky, the breathtaking colors of a sunset or the mysteries of a full moon illuminating the landscape. But have you ever wonder how astronomers managed to understand what was happening in the sky? How did they calculate the distance from the Earth to the Moon, from the Earth to Sun and then to the stars and galaxies in our universe? It all really started when Erastosthenes used the difference in the angle of the elevation of the Sun between two different cities in Egypt to calculate -with a remarkable precision- the circumference of the Earth. After that, astronomers often relied on specific astronomical event such as lunar eclipses to estimate the distance from the Earth to the Moon and then from the Earth to the Sun and every other planet in our solar system. By the beginning of the 17th century, more than 1,800 years after Erastosthenes and while the renaissance had brought new life to science all across Europe, the distance from the Earth to the Sun was still not know with a good precision. But this was about to change…

The first scientific observations

On December 4th 1639, Jeremiah Horrocks became the first astronomer to observe a transit of Venus (http://en.wikipedia.org/wiki/Transit_of_venus). Horrocks observations allowed him to estimate the distance between the Earth and the Sun to be 95.6 million km, a much more precise number than the ~7 millions km estimated by Aristarchus of Samos almost 2,000 years before, but still quite far from the actual distance (149.6 million km).

After that, observations of the transit of Mercury were used to estimate the distance from the Earth to the Sun but the results were disappointing. Then, in two papers published in 1691 and 1716, Edmond Halley (yes, the same guy that Halley’s comet was named after. He predicted that the comet sightings of 1456, 1531, 1607, and 1682 were related to the same comet and predicted the return of the comet for the year 1758. He was right but died before he was proven correct) proposed that more accurate calculations could be made using measurements of the upcoming transits of Venus. But the next transits of Venus would not occur until 1761 (and then 1769) and Halley did not live long enough to see them (story of his life)… Although Halley was not there anymore, numerous other astronomers and explorers (including the famous James Cook) went on expeditions all around the Earth to observe the transits of 1761 and 1769. The calculations were not as precise as they have hopped but French astronomer Jérôme Lalande managed to use the combined 1761 and 1769 transit data to estimate the distance from the Earth to the Sun to be about 153 million km (remember, the actual distance is 149.6 million km), a much more precise estimate than anything that had been published to date. The observations by Mikhail Lomonosov from the Saint Petersburg Observatory also led to the conclusion that Venus had an atmosphere, which was a big discovery.

If the expedition led by James Cook was probably the most successful one (more for his explorations than for the actual observation of the transit of Venus which was rather imprecise), others did not have his chance…

The most unlucky astronomer of all time

Guillame Legentil (Guillame Joseph Hyacinthe Jean-Baptiste Le Gentil de la Galaisière if you want the full name…) was one of the ~120 astronomers who observed (or at least tried to observe) the 1761 transit of Venus. On March 16th 1670, he sailed from Brest (Brittany, France) to Pondichery, a French colony in India to observe the transit of Venus. But before his ship arrived, war between England and France had broken out and it was not safe to land in Pondichery which was disputed between the two countries (dam Britts!!!). Legentil had no choice but to return to Mauritus, his previous stop on the way to India. However, the winds were not favorable. They did not make it in time to Mauritus and Legentil had to observe the transit from the deck of the ship, preventing him from making any precise calculations. But Legentil did not get discouraged. He decided to stay in the South hemisphere until the next transit: 8 years latter. He spent some time mapping the East coast of Madagascar and decided to observe the 1769 transit from Manilla, in the Philippines. But in 1767, after a peace agreement between France and England, he was recommended by the French government to return to Pondichery where he arrived in March 1768. There, he built an observatory and patiently waited for the upcoming transit in June 1769. The day of the transit finally arrives! The weather has been perfect so far, but shortly before the transit starts, clouds came rolling in and blocked the view during the entire duration of the transit. An hour latter, the sun was shining again… And guess what: the weather was perfect for the whole duration of the transit in Manilla (where he initially wanted to be for this observation). But wait, story is not over… While he was getting ready to sail back to France his ship was delayed due to dysentery and then captured by a storm. Le Gentil had to go a shore at île de la Réunion (a small French island, East of Madagascar) and wait until a Spanish ship brought him home to France. In 1771, 11 years after he left France, he finally made it back to Paris … only to find out that he had been declared legally dead, his wife had remarried and his relatives had divided the assets between them.

In the end, he got his job back, remarried and lived happily (or at least we think he did) for the next 21 years. But still, what an adventure … and an adventure good to remember when I get worried about missing my connecting flight in Denver, on the way to the West coast for my own expedition to observe the 2012 transit of Venus.

If you are interested in the history of astronomy, I strongly recommend this amazing book by Simon Singh: ‘Big Bang: The Origin of the Universe‘ Reads like a thriller!

A lot of the information about LeGentil comes from this website:  http://www.astroevents.no/venushist2aen.html

Planning my own expedition for the 2012 transit of Venus

The transit was visible from anywhere in the US, but the more North-West you would go, the longer you could enjoy it. From Bloomington, the Sun would be already quite low on the horizon by the time the transit starts and I could observe it for only ~ 2 hours before sunset. So, I decided to go on the coast of California where I could enjoy ~5 hours of transit + a unique sunset on the Pacific (while the transit is still ongoing) + high probability of clear skies. It was also a good occasion to go visit my friends in San Francisco and Santa Cruz.

A week-end in San Francisco

On Friday June 1st, I leave the lab in the afternoon to go catch my flight in Indy. After a short layover in Denver, I arrive at the SF International Airport at 11pm, just in time to catch the last BART (= the local metro) to Berkeley. Bastien and Mathilde are waiting for me at the BART station in Berkeley and they help me to carry all my stuff (>100 pounds / 50Kgs of luggages) to their apartment. I haven’t seen them in 2 years, so we have tons of stuff to talk about but it’s already past 1am (= past 4am on the East Coast), time for me to go to bed. Saturday was a typical tourist’s day in San Francisco: wandering in the district of the mission, taking pictures of Maxime Le Forestier’s blue house (French people will understand), crossing the Golden Gate Bridge in the fog… It was also the occasion to see my friend Holly (see: Climbing mount Fufi … in my very own way).

After a good diner at Revival (a really nice restaurant in Berkeley) with my friends and a good night of sleep I was ready for a second day of wandering in San Francisco. This time I will be by myself but I borrowed Mathilde’s bike so that I can more easily go from one district to the other. Biking in San Francisco was one of the biggest highlights of this trip! Everything is so much easier with a bike. From the BART station ‘Embarcadero’ it will take me less than 10 minutes to go to Fishermans wharf, where I will have lunch with Manu, another of my friends from Lyon who is now living in San Francisco with his wife and their two daughters. After lunch I have an hour to kill before going to Alcatraz and I decide to go biking down the legendary Lombard Street. But of course, one needs to earn this pleasure by biking up one of the streets leading to Lombard Street. I started biking on Hyde street from the piers and trust me: it’s very steep! While I was struggling to keep going on it’s almost 30° grade slope, people in the streetcar ahead of me and on the sidewalks started cheering on me to help me and some of them even took pictures (I guess they don’t see that many crazy bikers going up these very steep streets). I had the feeling to be a professional cyclist in Le Tour de France … great feeling! After this intense effort I’m rewarded by taking a left turn on Lombard street and biking down this legendary street.

Lombard street

Five more minutes of biking and I’m at pier 33 where I will take the boat to Alcatraz. The visit of Alcatraz is really interesting, with a great audio guide. This place has such a rich history, and not only because of the jail but also because of it’s pre-jail history and of course the occupation by Indians of all tribes (see: http://en.wikipedia.org/wiki/Occupation_of_Alcatraz)

After the visit of Alcatraz I quickly go to the pier #39 where a colony of sea lions are happily sun bathing and pose for tourist to take pictures. These animals are really awesome. If reincarnation is true, then I want to be a sea lion in my next life 🙂

Two days in Santa Cruz

After saying good bye to the sea lions, I go back to Berkeley where Bob will pick me up to go to Santa Cruz. Time to say good by to Bastien and Mathilde. On the road, Bob and I can enjoy a beautiful moon rise. I try to take some pictures from the car but did not quite manage to capture the beauty of this moon rise.

Moon rise over the Shipping Container Cranes of Oakland port (according to the legend, this is what inspired George Lucas for the Star Wars AT-AT Walkers)

We arrive in Santa Cruz just in time to go grocery shopping before the store closed and after a diner made of sushis, cheese and pizza I go to bed while thinking: “will I have the courage to get up at 4 am to take pictures of the partial lunar eclipse?” (yes, there was also a partial lunar eclipse that night … so many astronomical events in such a short amount of time!). Well, I was too tired to take pictures, and anyways, in the middle of the night the clouds started to fill the sky.

On Monday I spent most of my time on the UCSC campus, trying to work on my laptop from the biology building while it was pouring rain outside. In the evening it finally stopped raining and we went for a nice trail run with Bob and one of his friends before heading downtown for diner with Bob and his girlfriend: Jaime.

Transit day!

Tuesday: finally the day of the transit has arrived! Blue sky, good weather forecast, I know it’s gonna be great. Bob has to go work in the lab but Jaime gave me a ride to my observation spot, a parking off highway 1, about 20 miles North of Santa Cruz (Gazos Creek State Beach to be precise: https://maps.google.com/maps?q=37.166447,-122.36171&ll=37.166199,-122.359827&spn=0.002125,0.004801&num=1&t=m&z=18). Why this place? Because from there the sunset would be perfectly aligned with the Pigeon Point Lighthouse, located about 2 miles North-West. That should produce dramatic views of the sunset. I set up my telescope on the almost empty parking, show the sun through the h-alpha telescope to Jaime and to the other people parked there and wait for the transit to begin, in about one hour.

Jaime standing by her car while I’m finishing to set up the telescope.

View in direction of Pigeon Point Lighthouse

360° view from my observation spot

Jaime has to go for a job interview and I’m now alone with the Pacific ocean, waiting for Venus to begin its spectacle. I love this atmosphere. The wind is blowing without any interruption and I think about all these explorers from the 18th century who traveled for years to observe the same thing.

3pm: the transit should begin soon. I start taking pictures with a camera dedicated to making a time-lapse movie of the event (the camera with the big zoom that you can next to the telescope on the next pictures).

After a couple of minutes I can see it through the telescope: a tiny incisure on the edge of the Sun, rapidly growing until the entire surface of Venus is in front of the Sun, giving the visual impression of a small hole in the Sun. I keep starring at this tiny black disc, slowly moving across the face of the Sun. From time to time I set up a second camera to take pictures through the telescope but my focus was always a bit off.

Photo montage showing the progression of the transit over ~4 hours

And here is the time-lapse showing the progression of the transit:

From time to time a car would stop. I offer people to look at the transit through the telescope and I even spent half an hour helping a guy to take pictures with his own camera (I had an extra solar filter that I somehow managed to fit on his camera). Sometime around 6pm Bob and Jaime join me for the end of the observation.

7.30pm: less than an hour until sunset, I turn off the camera that was taking pictures for the time-lapse movie, unmount the telescope and get ready for the sunset pictures. I set up two cameras to automatically take pictures from the beach where Bob and Jaime will enjoy the sunset while I run to the other side of the parking with a third camera to take pictures from the place where the Sunset will be perfectly aligned with the lighthouse. Five or six other people are there, taking pictures. The sun gets low on the horizon and I can feel the tension rising among the other photographers. Will these clouds block the view at the critical moment of the Sunset? Well, the pictures below should answer the question…

See the tiny black spot on the Sun (bottom-right) ? It’s Venus… I strongly recommend you click on the image and then on the link to the full resolution picture.

For those of you too lazy to click on the image and go see the full resolution picture, here is a crop centered on the Sun:

From the beach, the sun was setting at the left of the lighthouse as you can see on this time-lapse video:

But the spectacle was beautiful, with the sand changing colors from dark brown to glowing gold while the sun passes across the clouds (full screen HD strongly recommended for this video):

The night is falling, I hurry up to get all my equipment into the car and we head back to Santa Cruz for a great sushi diner with Bob. Back to Bob’s house I have to pack everything in my suitcase and my mountaineering bag (every time I travel I have to unmount the telescope in many pieces so that it fits in the suitcase…) and go to bed as soon as possible. Tomorrow I’ll have to get up at 6am to go catch my flight at the San Francisco airport, going back to Bloomington and already dreaming of some new adventures.

I know it’s gonna be hard to get back to work, thousands of miles away from the coast, especially after witnessing such an amazing sunset…

This entry was posted in Astronomy, Misc, Past trips. Bookmark the permalink.

4 Responses to June 2012: San Francisco and Transit of Venus

  1. P.J. says:

    François Leforestier s’appelle Maxime. Mais peu importe le prénom, face à de tels spectacles!

  2. Pingback: Transit de Vénus du 5 Juin 2012 | On the road again

  3. Wow you are really passionate about Astronomy. Great explanations, photos and videos! I think I’ll stop by again!

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