Observations

2012 starts with a Time Ball drop

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The time ball at Sydney Observatory in mid-drop. Photo © Powerhouse Museum, Sydney.

A Time Ball drop? Is that some kind of Rocky Horror dance move you might ask? No, it’s actually an important part of Sydney’s history. When Sydney was young international communication and trade was done by ship. When sailing to Sydney a ship’s captain would calculate his longitude using a very accurate clock called a chronometer. In port Sydney’s Time Ball signalled the precise instance of 1-pm, to the nearest half a second, so ships could check the accuracy of their chronometers. It was the job of the Sydney Observatory astronomers to accurately determine the exact time to drop the Time Ball using measurements of the Sun and stars.

Sydney Observatory and its Time Ball began operation in 1858. At 12:55pm every day (except Sunday) the Time Ball was hoisted to the top of the tower and then dropped. Any captain watching the Time Ball knew it was 1-pm as soon as the ball began to fall. From 1829 to the 1920’s an estimated two hundred Time Balls where in use at major seaports around the world, ensuring ships could safely navigate the oceans. Today Sydney Observatory’s Time Ball is one of less than ten that have survived and continue to operate.

To celebrate the New Year Sydney Observatory will drop the Time Ball at exactly midnight on New Year’s Eve. So look up at the yellow Time Ball on the hill above The Rocks – when it drops 2012 begins.

Happy New Year to you all!

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