0618 GMT December 15, 2019
Australia is one of the first countries to celebrate as the clock stroke midnight before moving across Asia, the Middle East, Africa, Europe and finally the Americas.
Fireworks lit up the sky above Sydney Harbor a few hours before midnight on Sunday, kicking off the city's New Year's celebrations.
Samoa, Christmas Island and Kiribati were the first to celebrate the New Year. New Zealand quickly followed as tens of thousands gathered around Sky Tower in Auckland for five minutes of nonstop pyrotechnics exploding from the structure's upper decks.
But on nearby Waiheke Island, 30 kilometers away, authorities cancelled a planned fireworks display because of drought conditions and low water supplies for firefighters.
Japan is next to welcome in the arrival of the 'Year of the Dog' in the traditional way of praying for peace and good fortune at neighborhood Shinto shrines.
Food stalls had already been set up at Tokyo's Zojoji Temple, where people take turns striking the giant bell 108 times at midnight — an annual practice repeated at other Buddhist temples throughout Japan.
Thousands of people also filled the streets near Seoul's City Hall for a traditional bell-tolling ceremony to usher in the New Year.
The group of dignitaries picked to ring the old Bosingak bell at midnight includes Soohorang and Bandabi — the tiger and bear mascots for the Pyeongchang Winter Games and Paralympics in February and March.
Tens of thousands of people flocked to eastern coastal areas, including Gangneung — the seaside city that hosts the Olympic skating and hockey events — to watch the sun rise on 2018.
Those preparing to celebrate in New York City's Times Square were warned to brace for what could be one of the coldest New Year's Eve ball drops on record.
The coldest New Year's Eve in Times Square came in 1917, when it was -17ᵒ Celsius at midnight.
This year, the forecast is for -11ᵒC with a wind chill around -17ᵒC, which would tie for second with 1962.
In other areas of the country being gripped by the cold, some events are being cancelled or reconsidered.
New Year’s Day was celebrated on January 1 in 45 BC for the first time in history as the Julian calendar took effect.
Soon after becoming Roman dictator, Julius Caesar decided that the traditional Roman calendar was in dire need of reform. Introduced around the seventh century BC, the Roman calendar attempted to follow the lunar cycle but frequently fell out of phase with the seasons and had to be corrected. In addition, the pontifices, the Roman body charged with overseeing the calendar, often abused its authority by adding days to extend political terms or interfere with elections.
In designing his new calendar, Caesar enlisted the aid of Sosigenes, an Alexandrian astronomer, who advised him to do away with the lunar cycle entirely and follow the solar year, as did the Egyptians. The year was calculated to be 365 and ¼ days, and Caesar added 67 days to 45 BC, making 46 BC begin on January 1, rather than in March. He also decreed that every four years a day be added to February, thus theoretically keeping his calendar from falling out of step. Shortly before his assassination in 44 B.C., he changed the name of the month Quintilis to Julius (July) after himself.
Celebration of New Year's Day in January fell out of practice during the Middle Ages, and even those who strictly adhered to the Julian calendar did not observe the New Year exactly on January 1. The reason for the latter was that Caesar and Sosigenes failed to calculate the correct value for the solar year as 365.242199 days, not 365¼ days. Thus, an 11-minute-a-year error added seven days by the year 1000, and 10 days by the mid-15th century.
The Roman church became aware of this problem, and in the 1570s Pope Gregory XIII commissioned Jesuit astronomer Christopher Clavius to come up with a new calendar. In 1582, the Gregorian calendar was implemented, omitting 10 days for that year and establishing the new rule that only one of every four centennial years should be a leap year. Since then, people around the world have gathered en masse on January 1 to celebrate the precise arrival of the New Year.