ReedNavigation.com

Classes in celestial navigation and related topics
 

Lunars and Longitude

Winter / Spring 2026:
  • Register Mar 14,15 ATLANTIC session: 10am-4pm US Eastern time (1500-2100 UT), online.
  • Register May 11,12,13 PACIFIC session: 8pm-11:45pm US Eastern time (0100-0445 UT next calendar day), online.

Learn the art of Lunars, the famous celestial navigation method of finding longitude by observing the Moon in this intermediate-level workshop. Taught by Frank Reed, the world's leading expert on the history, science, math and practice of lunars. We cover practical application of the method as well as its extraordinary history, including primary-source evidence in the logbooks of the museum's collections. We will follow an extraordinary voyage in the 19th century, a Boston trading ship on a quest for coffee, sailing to India and home, all thanks to Lunars. And we'll follow William Bligh and the "Bounty" to Tahiti and the famous mutiny that followed, relying on the Moon for their successful navigation.

Lunars were widely used at sea in the early 19th century in the era before chronometers became common. Lunars made global navigation possible. Observing with a fine sextant, navigators used the Moon as a great natural clock in the sky. From James Cook and Nathaniel Bowditch to Joshua Slocum, lunars were a challenge that proved a navigator's skill.

Participants in this workshop will learn the fine details of adjusting a sextant properly for shooting lunars, tricks for taking accurate sights today, and easy methods for working with these infamously difficult observations both by modern and historical means. We'll also talk about some of the interesting mathematics and astronomical discoveries that made lunars possible. For a modern celestial navigator or navigation enthusiast, there is no better test of your sextant and observing skills. Weather permitting, we will have opportunities to take actual lunar observations.

All workshops: $ 149 per person, per workshop

Created and taught by Frank Reed, celestial navigation and astronomy consultant on the team that found Shackleton's "Endurance" in 2022. Also a recent guest expert in celestial navigation on Neil deGrasse Tyson's StarTalk on The National Geographic Channel.

If you're registered for an online workshop, you're invited to attend hour-long sextant practical sessions in Rhode Island and Connecticut scheduled as weather and other factors permit. These live, in-person sessions are included in your registration for online classes.

Comments:


Lee Schacter wrote:
A great course and teacher. Finally got my head around celestial navigation...
Greg Rudzinski wrote:
The online class "Lunars: Finding Longitude by Lunar Distance" was a very interesting introduction to the esoteric history of lunars as practiced at sea in the pre chronometer 18th century tall ship era. Practical instruction was also done demonstrating the physical process of observing a lunar with a sextant followed by a how to lunar sight reduction example using a pocket calculator, formulae, and tables. A very rewarding experience.

Greg Rudzinski
Retired Merchant Mariner
SUNY Maritime class of 80
Samuel S Lyness wrote:
Frank, a wonderful course in Lunars. I learned a lot. I admire your teaching skills and your astounding fund of knowledge. I would wish to emulate your style of instruction. Best regards, hope to sign up for your course in Cel. Nav. in Age of Sailing.
Sam Lyness

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