Friday, June 8, 2012

The Transit of Venus

Credit: NASA Solar Dynamics Observatory (SDO)
The transit of Venus was over on June 6 and I did not have time to finish this post while it was happening. However, this transit is rare enough that it's worth mentioning even belatedly. Indeed, another transit of Venus will not occur this century.

A few basic facts
The transit of Venus occurs when Venus passes between the Sun and the Earth and becomes visible against the solar disk. The planet  can be seen as a small black disk that moves across the sun obscuring small portions of the solar disk for a duration of a few hours.  In 2012, the transit lasted six hours and 40 minutes and was observed over two days: June 5 and June 6. The radius of Venus is a little over 6000 km. Venus is a rocky planet of about the same size as the Earth, and significantly larger than the Moon. However, Venus appears to obscure a much smaller portion of the Sun than the Moon from Earth because it's further from us. For this reason, the transit also is slower than a solar eclipse.

A bit of History
The last transit of Venus occurred 8 years ago in June 2004. These transits are predictable. They occur in a pattern that repeats every 243 years, with pairs of transits eight years apart separated by long gaps of 121.5 years and 105.5 year. The eight year gap is because the length of eight Earth years is almost the same as 13 years on Venus, so every eight years the planets are in roughly the same relative positions. The next transit of Venus will occur in December 2117, and the previous one was in 1882. The transits are so rare because of the inclination of the orbit of Venus relative to the Earth. The first transit was observed in 1639 and was used by Jeremiah Horrocks to correct Kepler's prediction for the orbit of Venus. Many people observed the transit of Venus in 2012 the same way Jeremiah did it so many years ago by focusing the image of the Sun through a simple telescope onto a piece of paper.

 How can scientists learn from this event today?
Scientists will use this event to test methods used to characterize extrasolar planets from transits events against what we already know about Venus, and to learn more about Venus. We can see how accurate is the prediction for the diameter of Venus relative to the diameter of the Sun from the dip in the sun's brightness. This event is also expected to improve our understanding of the atmosphere and climate of Venus, and to provide a testbed for methods of finding the atmospheric composition of extrasolar planets from transit events.

Did I see the transit of Venus in Zurich?
Not really. It was cloudy and too early in the morning. I have to confess I am not much of a practical astronomer/observer. I am more interested in the science that we can learn from events by analyzing data from instruments much more powerful than my eyes rather than in observing events myself. I do love to look at the beautiful images and videos that NASA provided for this transit.

For those who remember the transit of Venus in 2004, there was not so much talk about it then even though the transit looked similar by eye/small telescope/fancy glasses. What makes this event more dramatic for me is that we have the technology to learn a lot from it now, while we did not eight years ago. Of course, it's also the last time we'll see Venus transiting in front of the Sun in our lifetimes, and I am glad 'the world' is making the most of it.

More beautiful images and videos
If you search for the transit of Venus on youtube you will find several videos from NASA including one where they photograph it from the International Space Station.

There are also images and videos that can be downloaded directly from NASA website:

Venus and dogs
This is a topic that everyone and their dog* is writing about (quote from David Tsang, postdoctoral scholar at Caltech)**.

* some of my astrophysicist friends at Caltech have dogs
**Dave's comment was related to my suggestion of writing a paper on the two solar mass neutron star that was observed in 2010. Of course, neutron stars are not directly related to Venus, but Dave's expression was something that popped into my head while writing this post. Why? Because it's applicable to this post as well. There is a lot of information on the transit of Venus already on the web (and in books), but I wrote about it because it made me understand it better.

Thursday, June 7, 2012

A Week in Paris

Chasing the birds in Paris

In May I went to Paris to attend the LISA Symposium (read the gravitational waves in space post if you are interested in the science; however, the trip to Paris deserves a post of its own.) The conference was held at the Bibliotheque Francois Mitterand, the National bibliotheque in Paris. It is a beautiful building that was named after France's longest serving president. It hosts the globes of Luis XIV, the longest reigning king in European history.  He reigned for 72 years and 110 days and became king before he was five years old. It is difficult to imagine trusting my five year old nephew, David, to be king and to lead a country. Of course, king Luis XIV had plenty of help in the beginning - with his mother and some cardinal being the actual rulers. However, he was considered of age at fifteen, went through the ritual of coronation, and eventually ended up being the Sun King, one of the most successful kings of France. So, it maybe that in the current epoch we ask too little of our children.

The globes of King Louis XIV are huge and show surprising detail. The non-explored coasts are blurry, while the explored coasts are drawn in solid line. They show a good knowledge of Africa, America and Asia, and even some knowledge of New Zealand. France had many colonies at the time and so geography was important.

My mom, David and Edward came to the bibliotheque when the meeting ended. It has very many wooden steps, and then a big platform on which the children fed and chased birds. They also saw the globes and some exhibitions from various donors. The latter included papers that looked like what I draw when I am bored with the difference being that those people have money and so the things they write or draw are valuable. Still, I am not sure I would donate my drawings to an exhibition even if I had tremendous amounts money (Why? This is a sample of my in-existent talent from grade school. It speaks for itself ... and note that my ability to draw has not improved since.)

We were not allowed to take pictures of the exhibits. Part of the reasoning behind this is that the value of old objects is maintained if they are kept in their original condition. The light from the numerous cameras can affect the paintings in similar ways in which the sun affects our skin;  it can change the colour of the image.

A small island on lac Daumesnil
The meeting was fairly long - from morning until 6:30 in the evening and by that time everything was closed. However, we skipped a day when there were mostly experimental talks and when to the park at the Lac Daumesnil where we rented a classic wooden boat with oars. The children loved the boat ride. We saw small turtles and a beautiful cave in the middle of the lake.  The lake also had what seemed like patches of oil in the water, which made us wonder what had been washed in the lake.

On Thursday, we went to a restaurant that Philippe selected whose former guests included Picasso and Francois Mitterand, who had ordered a curry. Mihai and I shared a fish dish, which was delicious. In addition to Philippe (my current postdoc advisor) and our research group in Zurich, we were also joined by a graduate student from Netherlands. She was originally from Nepal. We learned a bit about the tallest mountains in the world:  8 out of 10 of  the tallest mountains are in Nepal, which also has extremely high real estate prices (of the order a thousand of dollars per square meter) even though the population there is still fairly poor. There was no communism there and so land has always been thought as valuable. On the way back we saw the Eiffel tower from the metro, which goes overground in some areas in Paris.

First Impressions of Paris
Collective nursing...

Mihai at the oars
 Paris is a big city that feels very much alive with traffic and people that appear busy and are moving fast. For example, Parisians like to walk on the stair-like elevators in the metro/train stations.  In the US they always stand on those and I think in Switzerland people also seem relaxed. Time and customer service did not seem to matter so much at our hotel/apartment building, which was nice otherwise. They did not include the code to open the front door or to access our room, and forgot to mention that nobody would be there on Sunday. We arrived on Sunday, and  had to wait for several hours. Eventually, we received the code and were able to enter. The next day we received 2 Euros for our trouble. In the US, they would have apologized and given us at least a free night. However, I was pleasantly surprised that the conference was flawlessly organized, and the hotel was walking distance to the bibliotheque. It was also well catered and the food was particularly good.

The smoke behind the hotel
As expected, Paris is dirtier than Zurich.  I like Zurich much better for raising children because Zurich because it is a safe and relatively clean city. The walls, the corners and doors on most streets in Paris smell badly like pee. The non-touristic areas are full of poor people. Some are homeless. They live in tents or on the vents where the warm air exits the metro station, and seem to move surprisingly little. I guess they are afraid of losing their spots. Near various cement mixing places on the river Seine there were large groups of people looking for work in construction. We have also seen the police stopping (foreign) cars in search for drugs.

Next to a statue with soldiers and slaves/prisoners of war
In spite of all this dear reader, if you love art, you should visit Paris. The museums, the parks with plenty of beautiful statues and small lakes with boats to rent, and the National Biblioteque are all superb. Paris really is a center for art. Weather-wise, I think Paris is close enough to London to get its share of rain. It did rain the first day we were there, and we did not have appropriate attire for that. Luckily, the rest of the time was sunny just like it was predicted on the weather channel.

Walking along the Seine
Mihai was singing these two variants of the song below as we were walking through Paris. I am not exactly sure where he got it from - and I am also not sure I have my tenses right in French, but these verses are the closest that I can get to an appropriate ending for this post today.

"Le Parisienne, Le Parisienne, ...
   ils vivre sur la Seine."


"Le Parisienne, Le Parisienne,  
ils vivent sous le ciel près de la Seine"

Here it's important to point out that both Mihai and I are tone deaf. But even though the French are socialists - they still have streets named after Lenin, but not one with Stalin's name - they believe in the freedom of expression in all forms of art.