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Dakota Datebook

Total Lunar Eclipse at Fort Mandan


Meriwether Lewis and William Clark found many ways to occupy their time during the winter of 1804-05 at Fort Mandan near present day Washburn, North Dakota. They met regularly with the neighboring Mandans and Hidatsas, with whom they traded, provided medical care and shared dances and other gatherings. The men of the Corps of Discovery hunted the surrounding plains and tended to their watercraft. They also endured frostbite.

In one of the most joyous moments that winter, Shoshone teenager and interpreter Sacagawea gave birth to a boy, Jean Baptiste Charbonneau. Clark nicknamed the boy “Pomp.” Lewis helped hasten the boy’s birth using rings of a rattlesnake’s rattle, which were broken and mixed with water and given to Sacagawea, who was in painful labor. Minutes afterward she delivered the boy.

Lewis and Clark kept up with their journals during their three-year journey, though large gaps exist in Lewis’ writing. On this date in 1805, they recorded observations of a total lunar eclipse. A total lunar eclipse is unusual, occurring on average, about once every six years.


The eclipse seen from Fort Mandan lasted between midnight and 3 a.m. Lewis had only the small, refracting telescope of his sextant to observe the eclipse. Lewis also used a chronometer, a precision timepiece. Clouds obscured much of the eclipse, with its ending phases the most visible. Lewis and Clark used their observations of the eclipse and its phases for determining their longitude and the location of the native village, though Lewis had doubts about the accuracy due to the clouds.

The following day, the weather wasn’t bad at Fort Mandan. Snow began to melt. The wind shifted. Four Hidatsa dignitaries visited Lewis and Clark. Hunters brought meat for the expedition’s men.

The Corps of Discovery was in present-day North Dakota for 213 days over two separate visits – longer than their time in any other modern-day state that they traversed on the journey to the Pacific Coast and back.

And here’s an item to look forward to in your own datebook: The next total lunar eclipse visible in North Dakota will be on May 15th, 2022.

Dakota Datebook by Jack Dura

Reid. R. (1988). Lewis and Clark in North Dakota. (2nd ed.). State Historical Society of North Dakota: Bismarck, ND
Email communication with Sherry Fieber-Beyer. 2020, November 2.

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