Transit
of Venus
Exactly
one year ago this very day we witnessed a miracle – two really, if the manner
of its appearance could also be counted.
We had
known for months (years actually) that the rarity of Venus passing directly
between the sun and the Earth was to occur on this very day, and viewable for
much of the event in our location. These transits of Venus are celestial
rarities, happening in pairs separated by eleven years, and then not again for
over 100 years. The transit of eleven years ago wasn’t visible from North
America, so we had just this one chance to view the transit. After this, very
few people, if any, would be still living to witness the next.
Halley
predicted transits of Venus in the early 1700s, and he instructed future scientists
(known then as natural philosophers) of the 18th century to mount
expeditions to the far corners of the globe so that the transit could be viewed
from differing locations. With variant timing of the entry and exit of Venus
across the sun’s disk on account of different vantage points, Halley claimed
that parallax could be used to calculate the relative distance of the planets
in the solar system. Halley knew then that he’d never live to see his
instructions carried out, as the pairings weren’t until 1769 and 1780, well
after his own death.
It is
astonishing and inspirational to read accounts of the voyages and hardships
undertaken during both these early transits, with years spent in preparation to
capture the few precious hours in which Venus ingresses, transits, then
egresses the sun’s disk. So many factors could conspire to thwart the effort.
We had
been waiting for weeks, knowing just like the explorers of 200 years ago when
to expect the transit’s beginning. With luck, we’d have a few hours of viewing,
before the evening sun would set below the horizon, preventing our egress view.
Four
days prior an unusual nor’easter arrived, with cold, wind-driven rain that was
forecasted for days. It was as cloudy as a bleak November stretch, and the
morning of the transit saw a misty rain. At 4:00 pm, the clouds showed signs of
breaking, with individual cloud shapes taking form among the leaden sky. At
5:00 there were small patches of blue, and we quickly ferried our telescope up
to the farm parking lot to set up and wait.
Ten
minutes out, the clouds parted, and the sun shone brilliantly for the first
time in days. I held a white sheet of paper in front of the eye piece, set back
far enough so that the image of the sun from pointing the telescope in its direction
was cast as a dinner-plate sized projection, complete with sunspots shown
clearly on the paper.
With
our friends as witness, we watched. “There!” someone called out, and the first
bubble of Venus made its push into the bright disk, as a tiny dark circle
slowly traversing across.
We
watched in silent wonder for fifteen minutes, knowing that millions of miles
away Venus was directly in line between us and the sun, moving inexorably in
its orbit like a celestial machine, predicted for this very day over 200 years
ago.
The
clouds closed back upon us, and the sun shone no more that day. It was indeed a
miracle.
Notes:
Yarrow
in bloom
Birdsfoot
Trefoil in bloom.