A Moonrise and a Reflection
By Luca Vanzella
On 27 October 2015, in a calm and crisp evening with very clear skies, Alister Ling and I photographed the rise of the Full Hunters Moon in deep twilight as seen from Riverside Drive.
Alister and I were enjoying the beautiful evening twilight colours and chatting away when I suddenly noticed a bright glow on the Innovation Centre for Engineering (ICE) building at the University of Alberta campus. “What is that?” I wondered out loud. We grabbed our binoculars and looked – it was the reflection of the Moonrise on the north facing windows of the ICE!
Our cameras were pointed towards the downtown skyline, steadily shooting timelapse frames as the Moon peaked out from behind the Epcor tower and rose above the apartment buildings along the Promenade. We couldn’t move the cameras as that would spoil the timelapse and it was too late to start a timelapse of the reflection. But the reflection sure was bright! I shot the scene with my phone to timestamp the reflection so I could figure out the geometry.
From our location on Riverside Drive, about 40m south of the middle bench, the ICE is at about azimuth 108. At the timestamp of the phone image, the Moon’s azimuth was about 72 and it was at an altitude of about 1.4 degrees. 108+72 = 180 degrees which means the north facing windows of the ICE were properly oriented for the “angle of incidence equals the angle of reflection” that we learned in high school geometry, which is why we were able to see it.
Another opportunity for a moonrise and reflection combination presented itself a month a later on 30 November 2015, again at Riverside Drive. This time, a waning Gibbous Moon would rise a bit further north, so we would have to position ourselves at the north end of the drive.
The appointed date came and it was clear, and this time Alister and I were ready. Alister pointed his camera at the west downtown skyline while I aimed my camera at the ICE. We shot at differing focal lengths but the same timelapse interval.
I shot the scene with my phone to timestamp the maximum reflection. This time, the ICE was at about azimuth 109 and the Moon’s azimuth was about 71, at an altitude of about 1.5 degrees.
Our efforts produced quite a nice timelapse of the moonrise and its reflection on the ICE. But it was a Gibbous Moon and what I really wanted was a Full Moon.
Five Years Later
Each January, I would review the Moonrise opportunities for the upcoming year to look for circumstances with a Full Moon doing its reflection thing on the ICE. Well it took five years, but finally another opportunity presented itself on 30 January 2021, albeit with a 94% full Moon. I made plans to try again.
An unusually warm January with many clear evenings ended in a cold snap with cloudier skies, but 30 January looked promising. It looked like it would be fairly clear so I went to Riverside Drive, trudged through the snow and set up two cameras (Alister couldn’t make this event). I had forgotten how much of a pain it is to set up at -15 C but as Moonrise approached, I was ready.
The geometry was similar to the 27 October 2015 event, so I set up about 24m south of the middle bench. Since 2015, two new towers had arisen very close to where the Moon would be when its light would reflect on the ICE, but luckily they would not obscure the Moon from my vantage point. Unluckily however, low thin clouds muted the brightness of the low Moon and attenuated the reflection. I shot two simultaneous timelapse sequences, one on the Moonrise and one on the reflection.
When I reviewed the images, I saw that during the 6 minutes 20 seconds that the reflection was visible on the ICE, the Moon itself was visible only for a very brief time as the Epcor tower and low cloud obscured it. In addition, the reflection was not very bright, so a dual timelapse did not seem worth making. Especially because the Moonrise frames all required compositing since it was a dark rise. But I did manage to get some interesting images.
This time, I shot a panorama of the scene with a DSLR instead of my phone so I was able to make a panorama of the Moonrise with its reflection. The left side shows the first 20 minutes of the rise. The right side shows the maximum reflection of the (lowest left side) Moon on the ICE, when the Moon’s azimuth was about 72 at an altitude of about 1.3 degrees.
Below are closeup images of the Moonrise and the reflection.
Since it was a dark rise and a bit cloudy, the results are nice but not I had hoped for. I wonder how many more years must pass before an opportunity presents itself again but with a 98%+ Full Moonrise in twilight? Trees are getting in the way more and more at Riverside Drive, making it more difficult to get a clear view for a given Moonrise.
Here’s the reflection timelapse movie.
© 2021 Luca Vanzella.