transit of mercury

Yesterday morning was a unique event, the transit of Mercury across the sun.  It was to be half-way across by the time the sun rose in the Bay Area slightly before 7am PST.  A few weeks ago I booked a campsite at Fremont Peak expecting to camp out to stay above any possible marine layer fog.  But for a few days I had a lingering sore throat, so I didn't want to spend a night in the cold.  So, the plan changed where I would get up before 6am and check the sky: if fogged over, I'd drive to some nearby ridge (I planned Henry Coe State Park); if no fog we could observe from home.  We arranged with some friends to meet us at Henry Coe and go hiking afterward.  I readied everything the night before, cars gassed up and just waiting for direction.

As it turned out, there was no fog, so we were able to spend a pleasant morning at home.  The sun cleared Mission Peak it was shining down on the sidewalk and street a little after 7am.  Clara and I set-up the 70mm (actually 48mm with mask) refractor with solar projection funnel, and we could quickly see the tiny dot a little off center.  I moved the scope several times around the sidewalk and street since some distant trees were casting shadows as the sun rose higher.  I started making sketches and notes.

A little later the sun began to show in our back yard, so I moved the scope back there and set-up two more: my PST solar scope and Valerie's 6" f4 with full aperture white light filter.  The PST was freshly repaired with a new objective lens and filter, and I received it back from the manufacturer on Saturday, just in time.  It showed really nice views of prominences, of which there were several: fountains, fans, and spikes, a couple of arches, including one very bright one, and several broken arches.  The 6" showed Mercury as a sharp disk and was a very good view.  Surprisingly there were no sunspots.

Our friends came over during the mid-morning and we enjoyed the views.  It was fun to observe from home since people could break away and do other things, then come back a little later for an update on Mercury's progress.  I had to move the scopes around the yard a couple of times since the meridian tree was casting shadows. Fortunately there was always some area in the yard where we could set-up. Some of the sketches suffer from field rotation problems from moving the scopes, but you can clearly see the movement of Mercury over time.

Toward the end of the transit Mercury could be seen to moved almost real time -- the sun's limb was closer to it and acted as a frame of reference.  As it started to make third contact we could see the little circular nibble Mercury made.  It was best in the 6" but I could even see it on the 70mm's projection screen.  I had Clara stay at the eyepiece of the 6" to watch Mercury finish its transit, since I wanted her to see such an amazing event and remember it.  I asked her to promise to wheel me out of the nursing home to see the next North American Mercury transit thirty years from now, the morning of 7 May 2049.  This one will also be about halfway over when the sun rises in the west, so if we're still here & the weather is clear the events of the day should unfold the same way they did yesterday.