It is believed that our era leads count from Christmas. A year of the birth of Christ was figured in the 6th century by the Roman abbot Dionysius Small who made a mistake. The exact value of the mistake is not possible to determine, but the birth was going to happen about 4-8 years before the Christian era.
Stephen Hawking believes that it is impossible to move in time. Moreover, he stated that he had received experimental confirmation of this statement. June 28, 2009, Hawking has organized a party for time travelers, but the announcement of this event has made the next day on the Internet. No one came at a meeting at the specified time.
In 1903, the Wright brothers made their first flight. After 38 years, the Japanese bombed Pearl Harbor. And after 28 years, man landed on the moon.
To be more precise UTC time corresponds to the mean solar time, in some years by June 30 or December 31 International Earth Rotation and Reference Systems Service adds an extra second, which is also called a leap year. In those days, after 23:59:59 23:59:60 first talking, and then later 00:00:00 the next day.