Cape Bre­ton Weather: “Tran­sit of Mer­cury”

The Victoria Standard - - Weather - BILL DANIELSON

On Mon­day, May 9th, we earth­lings were treated to a tran­sit of Mer­cury, an event that hap­pens only about a dozen times each cen­tury. From about 8 a.m. to 2 p.m. At­lantic time, Mer­cury inched its way across the so­lar disc. I took a num­ber of pho­tos, one of which I present here for your view­ing amaze­ment.

Okay, it’s not the most thrilling photo ever. But get­ting the photo was much less than half the fun, and I need to share the ex­pe­ri­ence in or­der to re­cover from it.

The weather started out beau­ti­fully: clear skies, light north­west breeze, tem­per­a­ture +2°C on our deck. But the sun was in­tense. Time out to find a hat. And sun­block. Lather it on.

I knew I couldn’t just aim my cam­era at the sun and go snap. The sun’s way too bright, and Mer­cury would be in­vis­i­ble with­out mag­ni­fi­ca­tion. So I brought out my bird­ing tele­scope and tri­pod, to blow Mer­cury up. If I looked through the tele­scope while it was aimed at the sun, all that tightly fo­cused so­lar en­ergy would fry my eye. How­ever, by pro­ject­ing it onto a piece of pa­per a foot or two away from the tele­scope I’d be en­larg­ing the im­age and also dim­ming it. Then I’d take pho­tos of the pro­jected im­age. A sim­ple plan, easy to carry out.

As usual, the devil was in the de­tails. I leaned a large piece of ply­wood against the deck’s rail­ing and taped a sheet of pa­per onto it as a tar­get. One minute later, the morn­ing’s first gust of wind flat­tened the ply­wood. I went scaveng­ing for rocks to hold it in place.

It’s hard to aim a tele­scope with­out be­ing able to look through it. It takes trial and er­ror, es­pe­cially er­ror. Worse, my tele­scope’s dread­ful di­rec­tional con­trols slip and stick at ran­dom, mak­ing fine ad­just­ment im­pos­si­ble. I solved this by hit­ting the tele­scope with a suc­ces­sion of nudges and shoves, hop­ing to knock it into alignment with sun and tar­get.

Squint­ing badly. An­other time out to hunt for sun­glasses.

The winds blew stronger, the tele­scope be­gan vi­brat­ing, and the im­age re­sponded by jump­ing around like the bounc­ing ball on a sin­ga­long video. I tried to sta­bi­lize the scope with one hand. I also kept tweak­ing the im­age into sharp fo­cus, since any fuzzi­ness would ren­der Mer­cury in­vis­i­ble. Un­for­tu­nately, fid­dling with the fo­cus knob of­ten knocked the scope off tar­get. Nudge and shove some more.

In my third hand I held my cell phone, ready to take a photo if a well-fo­cused, un­bounc­ing im­age mirac­u­lously ma­te­ri­al­ized.

The sun moved up­ward and south­ward across the sky, but the tele­scope didn’t, not on its own at least, so my nudg­ing and shov­ing were al­most con­stant. Fo­cus­ing, too. And ev­ery 10 or 20 min­utes the im­age tracked right off the ply­wood, re­quir­ing that I un­stack the rocks, schlepp the ply­wood, restack the rocks, move the tele­scope, then re-aim and re-fo­cus it.

Just about the time I had all this down to a sys­tem, clouds de­vel­oped. Puffy fair-weather cu­muli, a wel­come sight on any day but this one. For a while they toyed with me; then they blan­keted the sky, eclips­ing Mer­cury, the sun, and my chances for more pho­tos. But I had pre­vailed, cap­tur­ing one use­ful im­age!

I hope that read­ers will find this col­umn help­ful when­ever they want to pho­to­graph a tran­sit. To help you pre­pare, here’s list (ar­ranged al­pha­bet­i­cally) of the sci­en­tific tech­niques in­volved. They are: aim, blow up, cap­ture, cuss, flat­ten, fo­cus, fry, hit, knock, lather, lean, nudge, project, ren­der, scav­enge, schlepp, shove, snap, squint, stack, sta­bi­lize, tape, tweak, un­stack.

Prac­tic­ing these tech­niques ahead of time will pre­pare you for tran­sit day. Take my word for it.

Mer­cury, the dot in the lower part of the photo, moved steadily across the face of the sunon May 9. The clus­ter of spots in the up­per half of the im­age is a sunspot group.

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