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The Question

(Submitted September 02, 1998)


I'm 17 years old. I'd like to know when the new millennium starts. Isn't it Jan 1st, 2001? Why do people get excited about 2000 then? How can I explain this to my friends? Please help.

The Answer

You are right that the millennium starts on Jan 1st 2001. There is no year zero, so the first millennium started on January 1, 1 C.E.*, the day after December 31, 1 B.C.E. The first millennium ended 1000 years later, on the night of Dec 31, 1000/morning of Jan 1, 1001, and the second millennium ends 1000 years after that, on Dec 31 2000/Jan 1 2001.

However, the year 2000 is when you have to throw away all your old printed checks and get new ones. It's the year that there will be computer failures due to Y2K bugs making them believe they have just jumped back a century. When you buy a car, it typically has a few tenths of a mile on its odometer, but you still celebrate when it clicks to all zeros.

The main reason people will celebrate the millennium on the night of Dec. 31 1999 is to hold big parties, and to hold them a year sooner than they would otherwise. I expect that, around February, 2000, people will start coming around to the belief that the millennium does indeed start with 2001, and plan their next party accordingly.

*C.E. and B.C.E. Common Era, and Before Common Era, are the deity-neutral terms for what used to be called A.D. and B.C.

David Palmer and Samar Safi-Harb
for Ask an Astrophysicist

P.S. Astronomically speaking, the end of one millennium and the beginning of the next does not have any special meaning. In particular, neither January 1, 2000 or January 1, 2001 has any special planetary or solar alignments. Even if they did, planetary alignments have no effect on the Earth.

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