Geminid Meteor 'Shower' - December 2020


Geminid Meteor 'Shower' - December 2020

Despite living in the southern hemisphere, with no moon and a clear night or two forecast, I decided to have a crack at capturing Geminid meteors in December 2020. But I was a bit rusty.

I was using a Star Adventurer 2i tracking mount to track a section of sky near the radiant through the night, so that the meteors captured could be 'stacked' to show the effect of the meteors all appearing to come from the one 'radiant' near the bright stars Castor and Pollux in the constellation Gemini.

The radiant near Castor and Pollux was not even visible above the horizon and trees at the time I setup the camera and mount (before going to bed for the night, Sunday 13th December). I did poor job of framing the camera the first night, which meant I changed it the second night. Which then meant I had two completely different frames to merge, rather than one simple frame that was common through the capture sequence.

I rattled off several thousand 4 second exposures each night, with a Sigma 20mm f1.4 lens at ISO12,800 (straight to JPG files). Out of these I found about 70 exposures with meteors the first night (really the morning of Monday 14th) and another 20 or so on the second partly cloudy night by which time the shower was also well past its peak.

I registered all the frames together from each night and then combined them in Photoshop, masking each layer to reveal just the meteor and with each layer set to 'Lighten' blending mode. The stack of meteors from each night is shown below.

Meteor Stack from Night 1 (Monday 14th Dec AM)

Meteor Stack from Night 2 (Tuesday 15th Dec AM)

Because of how poorly framed these were, I subsequently shot a four-frame panorama of the same area of sky with the same lens, around three weeks later. I then aligned each of the two meteor stacks with this panorama to produce this final composite image. When set against the horizon as it was at this moment in time, six meteors placed over the foreground trees, so I have 'digitallly' moved them into the nearby sky. All the other meteors are shown with correct alignment relative to the stars as at the moment they occured, which reveals the nature and position of the meteor shower 'radiant'. But having a foreground in the image must be considered 'digital art' as the sky was moving relative to the horizon through the several hours each night during which the meteors were captured. I hope that makes sense.

I happened to wake up while it was (just) still dark the first night so stepped outside to observe a few meteors visually. I saw five Geminid meteors in the first minute and a half (including two almost simultaneously) which is astounding observing from the southern hemisphere with the radiant low on the horizon. But then I saw only one more in the next 20 minutes, plus six 'sporadic' meteors until the early summer twilight forced me back to bed. That's what observing a typical meteor 'shower' is like - keep your expectations very low.

Geminid Meteor Shower - Composite Image - Monday 14th and Tuesday 15th December 2020

Needless to say, capturing images like this takes a bit of effort, and the processing even more so. It's taken me a month to produce but that's my story of the Geminids for 2020.