The Great Transit Expedition of 2019

On November 11, I traveled to the near-flung corners of my backyard to observe the rare transit of Mercury across the Sun.

History is replete with tales of astronomers traveling to the far corners of the Earth to watch dark objects pass in front of the Sun — the Moon in eclipses, and Mercury and Venus in transits.

On November 11, to take in the last transit of Mercury until 2032, I had planned a trip to a location more likely to have clear skies in November than at home. A 3-day drive to southern Arizona was the plan.

But to attend to work and priorities at home I cancelled my plans. Instead, I decided to stay home and take my chances with the Alberta weather, perhaps making a run for it a day’s drive away if needed to chase into clear skies.

As it turned out, none of that was necessary. The forecast for clear, if cold, skies held true and we could not have had a finer day for the transit. Even the -20° C temperatures were no problem, with no wind, and of course sunshine!

Plus being only steps from home and a warming coffee helped!

As it turned out, the site in Arizona I had booked to stay was clouded out for the entire event. So I was happy with my decision!

For my site in Alberta, as for all of western North America, the Sun rose with the transit in progress. But as soon as the Sun cleared the horizon there was Mercury, as a small, if fuzzy, black dot on the Sun.

As the Sun rose the view became sharper, and was remarkable indeed — of a jet black dot of a tiny planet silhouetted on the Sun.

I shot through two telescopes, my 4-inch and 5-inch refractors, both equipped with solar filters of course. I viewed through two other telescopes, for white-light and hydrogen-alpha filtered views.

I was able to follow the transit for three hours, for a little more than half the transit, until Mercury exited the Sun just after 11 a.m. MST. The view below is from moments before Mercury’s exit, or “egress.”

I shot still frames every 15 seconds with each of the two cameras and telescopes, for a time-lapse, plus I shot real-time videos.

At this transit Mercury passed closer to the centre of the Sun’s disk than it will for any other transit in the 21st century, making this event all the more remarkable. That point is recorded above, from a shot taken at 8:19 a.m. MST.

Stacking a selection of the time-lapse frames, ones taken 1-minute intervals, produced this composite of the transit, from just before mid-transit until Mercury’s egress.

I assembled all the best images and 4K videos together into a movie, which I narrated live at the telescope as the transit was happening. I hope this provides a sense of what it was like to view this rare event.

The Transit of Mercury from Alan Dyer on Vimeo.

We won’t see another until 2032, but not from North America. The next transit of Mercury viewable from here at home is not until 2049! This was likely my last transit, certainly for a while!

This was my trophy shot! Bagged the transit!

P.S.: For my video of the previous transit of Mercury in May 2016, see my blog post which includes a similar compilation video.

P.P.S.: And for tech details on the images and videos in this blog, please click through to Vimeo and the video description I have there of cameras, scopes, and settings.

Clear skies!

— Alan, November 17, 2019 / © 2019 Alan Dyer / amazingsky.com