Record the shadow during a lunar eclipse
Photograph the same eclipse sequence at consistent scale. Compare contact progression and shadow shape while keeping ordinary lunar phases separate.
What you need
- Tripod and camera with repeatable focal length
- UTC clock and location
- A lunar-eclipse event with the Moon above the horizon
Collect the readings
- Plan around the event’s published contacts and local Moon visibility. The eclipse instants are shared worldwide; whether you can see them depends on your local horizon and weather.
- Retain a wide frame and a consistent focal length for a sequence before, during and after the partial phase. Use a shorter exposure when brightness is high and record each change.
- Fit the visible lunar limb and the shadow boundary separately. A circle fitted to only a short blurred arc has substantial centre and radius uncertainty; compare several frames.
- Compare synchronized images from another location. The same shadow progression is seen at the same instant, while the orientation relative to each local horizon can differ.
Compare the predictions
A lunar eclipse is Earth’s shadow crossing a full Moon.
A monthly crescent is viewing geometry of the illuminated lunar hemisphere.
A sequence constrains shadow geometry better than one isolated frame.
Open the related calculation →