Time Ball Introduction: In 1833, the Observatory erected a huge red "time ball" on the roof of the octagonal observation room. The red ball was strung on a metal pole and rose before 12:58 every day. Landed on time at 1 o'clock. In this way, passing ships on the Thames River can accurately synchronize time with the observatory by watching the takeoff and landing of this red ball. In 1924 AD, the Greenwich Observatory broadcast a time signal to space for the first time through the British Broadcasting Corporation, allowing radio listeners around the world to correct their clocks based on this time signal.