The January 2017 Waning Gibbous Moon, 25 hours apart

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Photographed from mid-town Toronto, Canada, at 23.30 EDT on Jan. 13 and again the following night, just after midnight (Jan. 15, at 00.30)

* Temperature -6° C. the first night; 0° C. the second night

 

This two-frame assemblage shows how the appearance of the Moon changes in one day (well, in this case 25 hours), as the terminator (the dividing line between day and night) moves from right to left across the visible face of the Moon. On average, the terminator moves across the Moon's face about 12.7° per 24 hours, as the Moon orbits planet Earth once per month.

 

In the right frame, the Moon is 96.2% illuminated by the Sun; in the left frame, the illuminated portion has decreased to 90.6%.

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Nikon D810 camera body on Explore Scientific 152 mm (6") apochromatic refracting telescope, mounted on Sky-Watcher AZ-EQ6 SynScan mount.

 

1200 mm focal length, f/8

 

* ISO 100, multiple stacked 1/250 sec. exposures

 

Subframes stacked in Registax

Processed in Photoshop CS6

(brightness, contrast, colour desaturation, sharpening, image rotation)

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Done