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The Great Conjunction

Erik Kuna
December 22, 202010:00 PM UTC (UTC +0)

It's been nearly 400 years since the Jupiter and Saturn planetary systems came this close to each other from Earth's vantage point. 800 years since it happened at night. For the past week, people around the world are looking up to see the long-awaited rendevous between our Solar System's massive gas giants and their moons. This convergence reached its peak on the night of December 21st, creating "The Great Conjunction."

Our launch photographer Erik Kuna ventured out a few hours from his home in Florida to capture the event that evening with some stills and video. From our perspective, Jupiter and Saturn will appear pretty close together but will still remain hundreds of millions of miles apart. It's important to note that while the conjunction is happening on the same day as the winter solstice, the timing is a coincidence.

“Conjunctions like this could happen on any day of the year, depending on where the planets are in their orbits,” said Henry Throop, an astronomer in the Planetary Science Division at NASA Headquarters in Washington D.C. “The date of the conjunction is determined by the positions of Jupiter, Saturn, and the Earth in their paths around the Sun, while the date of the solstice is determined by the tilt of Earth’s axis. The solstice is the longest night of the year, so this rare coincidence gave people a great chance to go outside and see the solar system.”

Erik Kuna for Supercluster

Erik Kuna for Supercluster

Erik Kuna gets down to the nitty-gritty of how he achieved these shots:

To capture the conjunction on video (embedded above) we used a Canon 5D Mark 4 in a 4K crop mode for extra reach.

Attached to an 800mm Telephoto lens that was extended further with a telephoto extender element, we ended up near a focal length of 1900mm for these shots. After the converters, the exposure value for the video was F/11 which meant we were shooting between an ISO of 800 and 6400 depending on the exposure we wanted to achieve.

In the Saturn and Jupiter flyby shot, the exposure settled between the two planets at an ISO of 1600 with a shutter of 1/60th shot at 24fps. On the other hand, when exposing for the moons, that exposure flipped to an ISO of 6400 with a shutter down at 1/24th of a second.

This camera was set on a tripod very low to the ground and behind covering to prevent the 15 mph winds from impacting the image and minimized vibrations at the extreme focal length. But as you can see in the video, even trying to minimize that, the breeze was still able to shake the camera slightly as the Earth rotated around the night sky.

Then the 4K end result at 1900mm was cropped further to 1080p which brought it closer to 3000mm. Needless to say, that magnification power was a big part of these images. 

For the images, the exposures again varied based on what was being imaged. The image above is a composite of three separate exposures that compensate for these variables in brightness. As for equipment, again, a DSLR was used to capture the images. In addition, this camera and telescope combo was mounted to a motorized equatorial mount head with a declination bracket that was Polar Scope aligned to keep Jupiter and Saturn within the frame for all the exposures. 

Shooting in RAW and with a custom white balance around 6000 Kelvin, the images were taken on a crop sensor Canon for added reach. Then the camera was attached to a small scope via a DSLR adapter with the crop factor ended up around 3000mm. As with the video, the photos were taken at F/11 which was the aperture of the scope.

The first image was taken of Jupiter at a lower ISO with a sequence of images following. Programmed with a MIOPS trigger, the DSLR was set to lock up the mirror then let the camera settle from vibrations introduced by the locking mechanism then take the shots a few seconds later. The camera repeated this process for a few frames. Then, a second exposure for Saturn with a higher iso ran through that same sequence and finally a higher ISO and longer Shutter speed for Moons and Stars. 

In editing, those frames were stacked, aligned, and combined to blend the exposures. The final image is a combination of three images, of which each of them was stacked with a bunch of images from each exposure to reduce noise and enhance the detail of Jupiter, Saturn, and the Moons based on their settings. The basic organization and editing was done with Lightroom, stacking in Starry Sky Stacker, and then blending in Photoshop. 

With the aid of both Sky Guide and Stellarium, we were able to align all the images for labeling based on the specific time code and GPS location. 

Erik Kuna
December 22, 202010:00 PM UTC (UTC +0)