Meridian Longitude 〈ULTIMATE • CHEAT SHEET〉

These extraterrestrial meridians allow planetary scientists to map rover locations, plan landings, and coordinate interplanetary missions. You might never use a sextant or calculate your angular distance from Greenwich. Yet, every time you set a time zone on your phone, ship a package across an ocean, or use Google Maps, you are leaning on the invisible scaffold of meridian longitude .

But 18th-century clocks broke on the rolling, humid, salt-sprayed decks of ships. Consequently, ships missed islands, crashed into reefs, or got lost for months. The British Parliament passed the , offering a prize of £20,000 (millions in today's money) for a practical solution. meridian longitude

So, the next time you check your watch, remember: somewhere, a meridian is crossing your location, linking you directly to the North Pole, the South Pole, and the historic observatory at Greenwich. But 18th-century clocks broke on the rolling, humid,