By Ira Polans

Frank Reed

This month’s featured talk is by Frank Reed on “Celestial Navigation: History and Future”. Before GPS and radio-based navigation aids, mariners crossed the oceans by observing the Sun, the Moon, and the stars and planets. Celestial navigation or “nautical astronomy” was a science practiced by ordinary men and women. Anyone could learn to find latitude and longitude using the Sun and stars, and anyone can learn how today, by applying just a little math to observations made with an optical instrument known as a sextant. In this presentation, In this talk Frank Reed will describe some of the science underlying celestial navigation, as well as some of the history. We’ll also consider how this ancient science remains relevant in modern contexts, even on the surfaces of other planets, like Mars.

After opening remarks and before the featured talk, member Jeff Pinyan will give a 10 minute talk on the 342nd anniversary of the determination of the speed of light by Danish astronomer Ole Rømer. In 1676, a Danish astronomer named Ole Rømer predicted an eclipse of Jupiter’s moon Io would occur 10 minutes later than expected. In so doing, he presented the first demonstrable proof that light has a finite velocity.

Prior to the meeting a meet-the-speaker dinner will be held at Winberie’s in Palmer Square. If you’re interested in attending the dinner please let me know at program@princetonastronomy.org by noon on January 8th.

If you’re interested in giving a 10 minute talk please speak to me after the presentations are completed during the meeting or by email at program@princetonastronomy.org.

Looking forward to you joining us at the January AAAP meeting!