Q When will the new millennium start and where on Earth will the new millennium first be experienced?
A The millennium starts on 1 January 2001. There was no year zero. Historians record the years as 1BC, and then AD1, AD2, etc. So AD1 was the first year in the first century and AD100 was the 100th year in the first century. AD101 was the first year in the second century. If you continue this up to today, then 2000 is the 100th year in this century and 2001 is the first year in the next. The eastern tip of Russia will experience this first, but the first large capital city to celebrate it will be Wellington, New Zealand.
Q Is the year 2000 a leap year?
A Yes. Perhaps nothing surprising there as it is divisible by four. But there is a further condition for the turn of a century to be a leap year. It must also be divisible by 400. So the last century year that was also a leap year was 1600. This is because the quarter day we gain every year - creating an extra day every four years - is not quite a quarter day. So every 100 years we forget the extra day in the leap year to bring our calendars back into order.
Q Do other mammals go through the menopause?
A No. This is probably because in the wild, mammals' natural lives aren't long enough to reach the biological stages that cause the menopause. So how long is the natural life of a mammal? If you plot mammalian heart rate against life span, most mammals lie on a straight line, showing that those with a fast heartbeat (such as mice and voles) live for only a few months or years, while those with slower heartbeats (such as elephants or tortoises) live for many decades. Based on the human heartbeat, we should naturally only live to our mid-thirties, never reaching the menopause. But due to advances in medicine and better diets we often live much longer and females reach the menopause in their forties and fifties.
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