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Dr. Ralph Chou

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The Transit of Venus

Posted: 06/08/2012 12:44 pm

The transit of Venus has come and gone, consigned to the history books as probably the most-watched such event in history. I went to Hawaii to observe the transit from the Onizuka Center for International Astronomy Mauna Kea Visitor Information Station along with 10 members and friends of the Royal Astronomical Society of Canada, Toronto Centre. We set out on Sunday, June 3 at just after 11 a.m. EDT and arrived at our hotel in Hilo on the Big Island at just before 9:00 p.m. Not having slept on the planes, we were all very tired by the time we checked in. Luckily, the restaurant staff decided to stay open long enough for us to have a late dinner before collapsing into bed.

Monday was spent playing tourist, visiting the Rainbow Falls in Hilo, and checking out the Volcanoes National Park. While Hilo was its usual, rainy self, the clouds and mist lifted while we were at Kilauea so that we could see the activity in the central crater in the caldera. It was an impressive sight. Once we returned to the hotel, it was time to check out equipment for the big event next day. Logging on to the Internet, it was somewhat disturbing to see the weather forecast for Mauna Kea the next day: At the summit 0 to 20 percent cloud cover with high winds, temperatures near freezing and 50 percent chance of fog. Uh, oh...

My email inboxes had about 200 new messages received since Sunday morning, with quite a few last-minute requests for information on safe solar viewers and filters for cameras and telescopes. At the end of April, I spoke at a Transit of Venus Symposium held at the University of Toronto, and my talk along with presentations of the other speakers had been posted on YouTube by the University of Toronto Scientific Instruments Collection, the organizers of the symposium. I suppose many of the inquirers had seen the YouTube video, since it garnered over 11,000 hits by Sunday evening. Being "on the road" made it difficult to respond to all of the inquiries, although I tried my best to do so before heading off to bed.

We were picked up at our hotel at 9 a.m. Tuesday morning by drivers Wendell and Steven with 4-wheel drive vans to carry us to the Visitor Center. We loaded our stuff aboard the vans and headed for Mauna Kea. Although it was cloudy over Hilo, as we drove up the Saddle Road, the clouds began to lift, and before long we could see clear blue sky over both Mauna Kea and Mauna Loa. Reaching the Visitor Center, our drivers were directed to park in the nearly full parking lot where we unloaded our equipment. The grounds were teeming with both casual and serious observers. Lo and behold, I met up with Dave McCarter of the RASC London Centre and his wife, who had set up a small refractor with solar filter, and were there as volunteers to assist the Center staff with the day's outreach program. We had a nice chat about what was going on at the site. Several members of the group were a bit unsteady on their feet due to the altitude, and Steven was allowed to drive them up to Hale Poaku (commonly called HP by observatory staff), the observers' residence where we were to have lunch after observing first and second contacts, then head to the summit to visit the Gemini North Observatory.

We successfully observed the beginning of the transit, although the contact times we recorded weren't very precise. We broke for lunch, then met with Joy Pollard, the Gemini North outreach officer, who conducted a safety briefing. The nine who were going to the summit went down to the Visitor Center from HP to catch the shuttle bus to the summit, getting the news that not only was it clear up there, but that there was a steady breeze and a temperature of about 40°F -- not bad. Nobody was allowed on the summit without warm clothing. Needless to say, lots of visitors in shorts and T-shirts were turned away -- were they thinking? Did they really expect it would be balmy up there? Much of the 8-mile ride was over a very bumpy dusty road that really stimulates the bladder... fortunately the last couple of miles were smooth pavement.

Alighting from the bus on the summit, one rapidly realizes that it isn't easy getting used to the altitude. That last few hundred meters walking uphill from the bus stop to the Gemini North was a real struggle not only due to the cold wind, but also the pounding heart and the lack of breath. Once inside the reception hall, Joy tested our blood oxygen, and three of us, including yours truly, got oxygen bottles since we were dangerously low. That helped a lot.

The tour of the facility went without a hitch. That is one humungous telescope! It has a mirror 8.1 meters in diameter and only about six inches thick. Active optics actuators help to maintain the mirror's shape as gravity distorts it in the various directions the telescope is pointed, while adaptive optics is used on the secondary to eliminate distortion of star images (scintillation) due to the air currents above the telescope. The control room looks like the bridge of a starship on Star Trek with a bank of monitors relaying all sorts of information about the state of the telescope, the object it is pointed at, and the weather conditions outside.

Before leaving the observatory, Joy tested everybody's blood oxygen levels, and the three of us seemed to be in immediate trouble as soon as the oxygen masks were taken off. She decided to take us down to HP in her vehicle as a medical emergency, while the others took the shuttle bus. We started down the mountain, and by the time we got to the second last switchback, we were already feeling much better. However Mauna Kea had one more ace up its sleeve -- the tire pressure sensor turned on as we entered the penultimate curve. This was not good news. Joy pressed on and got us to HP, where we found the right front tire nearly deflated. Talk about luck. We thanked her for her help, collected our equipment from the HP dining room, and set up to observe the last of the transit.

The sun disappeared behind the cinder cones to the west of HP before we could see 3rd contact, but we were able to image the transit until about 6:19 p.m. Then it was time to break the equipment down, pile back in the vans and head back to Hilo, where it was raining yet again.

On the Internet after dinner for the first time on Tuesday, there were requests for information as late as an hour before the transit started! Why??? I was happy to read that many of our friends at home in the Greater Toronto Area, and across much of North America were able to see at least some of the transit.

So ended the 2012 transit of Venus for my group. We won't be around for the next one in 2117, but at least a couple of us have now seen this century's two transits of Venus.

 
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