2430 A.D. is a science fiction short story by Isaac Asimov. It first appeared in the October 1970 issue of Think, the IBM house magazine, and was reprinted in Asimov's 1975 collection Buy Jupiter and Other Stories.

Early in 1970 the author was commissioned by Think to write a story based on a quotation by writer and social commentator J. B. Priestley:

Asimov, assuming that Think wanted a story that illustrated Priestley's quotation, crafted 2430 A.D. He selected the date because he calculated that at the then-current rate of human population growth, doubling every thirty-five years, that would be the year when the world's animal biomass would consist entirely of human beings. Asimov wrote the story on April 26, 1970 but it was rejected as Think had actually wanted a story that refuted the quotation. ("Well, they never said so," Asimov remarked later.) After Asimov wrote a second story that did refute the quotation, Think took the first story after all and published it in their October 1970 issue. The second story was later published in Analog magazine as The Greatest Asset. Both stories inspired by the Priestley quote were included in the 1975 collection Buy Jupiter and Other Stories.

Year 1500 (MD) was a leap year starting on Wednesday (link will display the full calendar) of the Julian calendar.

The year was seen as being especially important by many Christians in Europe, who thought it would bring the beginning of the end of the world. Their belief was based on the phrase "half-time after the time", when the apocalypse was due to occur, which appears in the Book of Revelation and was seen as referring to 1500.

Events

January–June

July–December

Year 500 (D) was a leap year starting on Saturday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Patricius and Hypatius (or, less frequently, year 1253 Ab urbe condita). The denomination 500 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.

Events

By place

Byzantine Empire

Britannia

Year zero does not exist in the Anno Domini (or Common Era) system usually used to number years in the Gregorian calendar and in its predecessor, the Julian calendar. In this system, the year 1 BC is followed by AD 1. However, there is a year zero in astronomical year numbering (where it coincides with the Julian year 1 BC) and in ISO 8601:2004 (where it coincides with the Gregorian year 1 BC) as well as in all Buddhist and Hindu calendars.

Historical, astronomical and ISO year numbering systems

Historians

The Anno Domini era was introduced in 525 by Scythian monk Dionysius Exiguus (c. 470–c. 544), who used it to identify the years on his Easter table. He introduced the new era to avoid using the Diocletian era, based on the accession of Roman Emperor Diocletian, as he did not wish to continue the memory of a persecutor of Christians. In the preface to his Easter table, Dionysius stated that the "present year" was "the consulship of Probus Junior [Flavius Anicius Probus Iunior]" which was also 525 years "since the incarnation of our Lord Jesus Christ". How he arrived at that number is unknown.