Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

October 29, 1999
See Explanation.  Clicking on the picture will download 
 the highest resolution version available.

The USNO Millennium Time Ball
Credit: United States Naval Observatory

Explanation: In the nineteenth century, dropping a time ball from a prominent location was a practical way of communicating the time to the surrounding country side and ships at sea. Initiating a fledgling time service for the United States, the U.S. Naval Observatory dropped a time ball at precisely noon every day begining in 1845. At the end of the twentieth century, in commemoration of this traditional method of disseminating time, the U.S. Naval Observatory has installed this ceremonial time ball atop its main building in Washington D.C. Dropping this time ball - at midnight Eastern Standard Time on New Year's Eve - will be the local culmination of a "round-the-world time ball drop" marking the beginning of the year 2000 and the beginning of the Third Millennium in 2001. Meanwhile, don't forget ... this year, in most of the U.S. Daylight Time ends at 2:00 am on Sunday, October 31.

Tomorrow's picture: Rock 'n Roll

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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
NASA Technical Rep.: Jay Norris. Specific rights apply.
A service of: LHEA at NASA/ GSFC
& Michigan Tech. U.