(NASA) Recorded on April 15th, thistotal lunar eclipsesequence looks south down icy Waterton Lake from theWaterton Lakes National Parkin Alberta, Canada, planet Earth. The most distant horizon includes peaks inGlacier National Park, USA. An exposure every 10 minutes captured the Moon’s position and eclipse phase, as it arced, left to right, above the rugged skyline and Waterton town lights. In fact, the sequence effectively measures the roughly 80 minuteduration of the total phaseof theeclipse. Around 270 BC, the Greek astronomerAristarchusalso measured the duration of lunar eclipses - though probably without the benefit ofdigital clocksand cameras. Still,using geometry, he deviseda simple and impressively accurate way to calculate the Moon’s distance, in terms of the radius of planet Earth, from the eclipse duration. This modern eclipse sequence also tracks the successive positions of Mars, above and right of the Moon, bright star Spica next to the reddened lunar disk, and Saturn to the left and below.