In 1715 Edmond Halley — the comet's namesake — did something no one had done before: he printed a map predicting precisely where and when the Moon's shadow would fall across England during a total eclipse, sweeping a band of midday darkness from the west country to the sea. He asked the public to observe and report, making it an early act of citizen science. It was the founding document of predictive eclipse cartography: proof that the heavens ran on laws exact enough to foretell the very minute the daylight would fail. Wonder, made punctual.

Maker: Edmond Halley
Date: 1715
Medium of the original: Plate
Original held by: Published London · Wikimedia Commons
Credit: Published London · Wikimedia Commons
Rights: Public domain, verified
Catalogue number: PA-00991

As chosen: 16 x 24 in, art print, classic frame
Picture	16 x 24 in
Outside size	17.6 x 25.6 in
Depth	0.9 in (22 mm)
Weight	[[REAL PROOF NEEDED: shipped weight per size and frame]]
Hanging	[[REAL PROOF NEEDED: hanging hardware Prodigi fits to this frame]]
Material	Enhanced matte art paper, 200 gsm; acrylic glazing
Made in	Charlotte, North Carolina, by Prodigi

Before a size goes on sale, the file is measured against it: pixels per inch at that size, how much of the picture a crop would lose, tone and sharpness. A size that fails is not offered, so there is nothing to choose wrong.

How the print check works

Sizes offered
Size	dpi	Grade	How it fits
8 x 12 in	361	Excellent	Trimmed 9.1%
12 x 18 in	241	Excellent	Trimmed 9.1%
16 x 24 in	180	Good	Trimmed 9.1%

Sizes withheld
Size	Why
8 x 10 in	Wrong shape: a 24% crop
11 x 14 in	Wrong shape: a 23% crop
12 x 16 in	Wrong shape: a 19% crop
16 x 20 in	Wrong shape: a 24% crop
18 x 24 in	Wrong shape: a 19% crop
20 x 30 in	144 dpi; a historical scan is never enlarged
24 x 30 in	Wrong shape: a 24% crop
24 x 36 in	120 dpi; a historical scan is never enlarged
30 x 40 in	Wrong shape: a 19% crop
36 x 48 in	Wrong shape: a 19% crop
40 x 60 in	72 dpi; a historical scan is never enlarged