Planetary Radio • Jul 28, 2015

The Royal Observatory, Greenwich and the Quest for Longitude

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On This Episode

20150728 louise devoy thumbnail

Louise Devoy

Curator for The Royal Observatory, Greenwich

Come with us on a visit to the home of the prime meridian for a conversation with the curator of the Royal Observatory, Greenwich about the race to create a practical means for determining longitude. It’s a dramatic story of precision astronomy and clock making, told by the Curator of the Observatory to Mat Kaplan as they examined the timepieces that helped revolutionize navigation. Bill Nye is on vacation, but we’re joined by Emily Lakdawalla with hazy news from Pluto, and Bruce Betts' explanation of the plutonium that just passed its namesake planet.

John Harrison's H1 timepiece
John Harrison's H1 timepiece Image: National Maritime Museum Collections
John Harrison's H4 timepiece
John Harrison's H4 timepiece Image: National Maritime Museum Collections

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This week's prizes are a fabulous Planetary Radio t-shirt and a beautiful new LightSail patch.

This week's question:

If you were a car company trying to market the Apollo mission Lunar Roving Vehicle, what would you name it, and what would your slogan be? There is no right answer. Answers will be judged based on humor and/or effectiveness or whatever other criteria we feel like.

To submit your answer:

Complete the contest entry form at or write to us at [email protected] no later than Tuesday, August 4th at 8am Pacific Time. Be sure to include your name and mailing address.

Last week's question:

As of July 14th, what was the unofficial name given by the New Horizons team to the dark feature that some have also unofficially called “The Whale?”


The answer will be revealed next week.

Question from the week before:

What was the mass of the plutonium flown on New Horizons?


You may think there are 10.9 kilograms of plutonium-238 dioxide on New Horizons, but the actual mass is about a kilo less than that. Anyway, it seems to have been enough.