Answers to all your questions about
The Start of The New Millennium

Science and Engineering Research Council

Royal Greenwich Observatory

Information Leaflet No. 29: 'The Start of The New Millennium'
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Summary:
This leaflet covers the most frequently asked questions regarding the start of the new (Christian, Gregorian) millennium and where to see the first sunrise.

In summary;
The year 2000 will be a leap year, the New Millennium and the New Century start at zero hours UTC (commonly known as GMT) on January 1st 2001 and on this basis, the first sunrise of the new millennium will be at places around the world where the Sun is rising at that moment.

Why the Year 2000 is a Leap Year:
Leap years were introduced into the calendar by Julius Caesar to ensure that the months of the year stay in step with the seasons.
This is necessary because the Earth makes one rotation about the Sun in 365.24219 days, which is clearly not a whole number of days.
Adding one extra day every 4 years would exactly correct for a year of length 365.25 days, but would over-correct for a year of length 365.24219.
To make a more exact correction, the Gregorian calendar introduced in 1582, stated that a century year will only be a leap year if it is divisible without remainder by 400, which is the case for the year 2000.
This approximation corresponds to an average year length of 365.2425 days and will amount to a discrepancy of only 1 day after 4,000 years.
The Gregorian calendar was adopted in Britain in the year 1752, when September 2nd was followed by September 14th.

Why the 3rd Millennium and the 21st Century start on 1 Jan 2001:
A millennium is an interval of 1,000 years and a century is an interval of 100 years.
In the system of counting years that we use, there is no year zero and the sequence of years near the start runs as follows;

Because there is no year zero, an interval of 1 year has only elapsed since the start of the era at the end of the year named 1AD. By a similar argument, 100 years will only have elapsed at the end of the year 100AD. It is therefore clear that 2,000 years will only have elapsed at midnight on 31 December 2000.
So the 3rd Millennium and the 21st Century will begin at the same moment, namely zero hours UTC on January 1st 2001.

The Origin of the Christian Era:
Early in the 6th century AD, Dionysius Exiguus (Denys the Little), a monk and astronomer from Scythia, now in Southwest Russia, compiled a table of dates for Easter in terms of the Diocletian calendar. He decided to reset the system of counting years to honour the birth of Christ so that the year 248 Anno Diocletiani became the year 532 Anni Domini Nostri Jesu Christi, known as 532AD for short.
In his scheme he believed that Christ was born on the 25th of December of 1BC, the year preceding 1AD.

Dionysius Exiguus made two mistakes. Firstly and quite understandably, he left out the year zero, because the number zero had not yet been 'discovered' in the West. His second mistake was in thinking that Christ was born at the end of the year 1BC.
Modern research indicates that Christ was probably born in 6BC, and certainly by 4BC when Herod died.

The idea of naming years BC was introduced by Bede in the 8th century.
Naming years in the Christian Era came into common use in ecclesiastical circles in the Middle Ages, but was not adopted for civil use until later.

Other Calendars and Eras in use:
Apart from the Christian calendar, there are about 40 other calendars in use throughout the world.
A few of them are listed, showing their years on 1 January 2000: Byzantine 7508, Chinese 4636, Indian (Saka) 1921, Islamic (Hegira) 1420, Jewish (A.M.) 5760.
The date on which the year changes is different for each calendar.

Why the Millennium starts at zero hours at Greenwich:
The "INTERNATIONAL CONFERENCE HELD AT WASHINGTON FOR THE PURPOSE OF FIXING A PRIME MERIDIAN AND A UNIVERSAL DAY", in October 1884, resolved to adopt the meridian at Greenwich as the prime meridian for "all the world", and the time and day at the Greenwich meridian as the universal time and day for "all the world".
In practice, this time, now more correctly referred to as UTC, is identical to what is widely known as GMT, and forms the basis for our claim that the Millennium will start at zero hours Greenwich time.
The same conference stated that the "universal day shall not interfere with the use of local or other standard time where desirable". Put simply, this means that in Sydney they are not going to wait until 10 next morning before celebrating the New Year.

Where is the Greenwich Meridian?
The famous brass strip seen at the Old Royal Observatory in Greenwich, London, marks the Airy meridian referred to in the 1884 treaty. However the meridian to which the UK Ordnance Survey is tied lies 5.79m to the west, while the GPS satellite meridian lies 96.5m to the east.

The International Date Line:
The International Date Line is an imaginary line of longitude located about 180 degrees east (or west) of the Greenwich meridian. This is the line across which the date changes by one day.
To understand this, imagine it is 3pm GMT on January 3 at Greenwich. 15 degrees east of Greenwich the local time will be 4pm, one hour later. In Japan, 135 degrees east, it will be 9 hours later, and the local time will be midnight January 3/4, while in East Australia, 150 degrees east, it will be 1am on January 4th.
In New Zealand, close to the International Date Line, the local time is 3am on January 4th.
Now let us return to Greenwich and imagine travelling west towards America.
For every 15 degrees we travel the local time is an hour earlier.
For example, the local time in California is 7am on January 3. As we continue west towards the International Date Line, the local time gets earlier and earlier, until at the date line the time is 3am on January 3.
This illustrates two things, firstly that there is no change of local time crossing over the Date Line, although the date changes by one day, and secondly, the obvious value in adopting a standard time and day that can be used to date events anywhere in the world without ambiguity.

Legal Status of the International Date Line, and Kiribati:
Despite its name, the International Date Line has no international status and was not defined by the 1884 convention, or any other treaty.
This means that countries close to the Date Line are free to choose which date they will observe.

On 23 December 1994 the Republic of Kiribati announced that; "With effect from 1 January 1995, all islands in the Line and Phoenix Groups within the Republic of Kiribati shall be on the same date of the islands in the Gilberts Group within the Republic, while their time are maintained to what they are as at present".
This perfectly reasonable decision from an administrative point of view puts a large eastward bulge in the International Date Line. It also places Caroline Island, since renamed Millennium Island, as a leading contender to see the first sunrise of the millennium.

Where to See the First Sunrise of the New Millennium:

The Super-purist View:
At the South Pole the Sun will have risen at the previous equinox around 22 September 2000, and will not set until about 22 March 2001 the following equinox.
Does this make the South Pole the first place to see the first sunrise of the new millennium on 22 September 2000, or only the last place to see the last sunset of the old millennium?

The Local Time View:
It is common cause that the start of the New Year is celebrated by people around the world according to their own local times, and that most people will celebrate the start of the year 2000 not 2001.
In the table below we list the times of sunrise for various places at the start of the year 2000.
In practice the difference in times between 2000 and 2001 is negligible.

The places in the above table are listed in order of the time of sunrise.
The times in column 5 are given in UTC, which is the time at Greenwich.
The last column gives the local standard time and makes no allowance for possible daylight saving times that may be in operation.
The time of sunrise depends on the height of the horizon and the observer.
The horizon is assumed to be at sea level, and the heights in column 4 refer to the observer.
The entry for Antipodes Island refers to Mount Galloway, and for Pitt Island, Mount Hapeka.

Will the Sun rise at the time Stated?
The calculation of the time of sunrise depends on using a model for the way the Earth's atmosphere bends light. For example when the entire disk is seen to be above the horizon the real Sun is still just below the horizon.
An average model of the atmosphere was used, so that the actual time of sunrise can vary by at most 1 minute, depending on actual conditions.

Time and Place of the First Sunrise in the UK on 1 Jan. 2000 (and 2001):
South Foreland, close to Dover, will be the first place in the UK to see the Sun rise on 1 January, 2000 (and 2001) at 07hrs 58mins.

ARVAL's Note:
El Bochinche, East of Tumeremo, will be the first place in Venezuela to see the Sunrise on January 1, 2000 (and 2001) at 06hrs. 15mins. In Caracas it will be at 06hrs. 45 mins., Jan. 1, 2000 (and 2001).

The last Sunset and the First Sunrise:
Anyone that accepts that the first sunrise of the New Millennium will be seen from Caroline Island has the possibility of flying 1,500 miles west to Western Samoa and seeing the last sunset of the old Millennium, 14 hours and 14 minutes later (apart, that is, from places south of the tropic of Cancer).

Produced by the Information Services Department of the Royal Greenwich Observatory.
Robin M. Catchpole, December 1997.

webman@mail.ast.cam.ac.uk

Updated: January 4 '98, June 27 '14

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