Naburimannu

Nabu - rimanni (also Naburianos, Naburimannu, Naburimani; * about 560 BC; † about 480 BC ) was a Chaldean astronomer and mathematician.

Nabu - rimanni, born in Babylonia, was the oldest known by name Chaldean astronomer. As the son of balatu he worked during the reigns of the Persian kings Darius I ( 522-486 BC) and his successor Xerxes I ( 486-465 BC). He was a contemporary of Kleostratos of Tenedos, Aeschylus, and Herodotus Ferehindus.

From the time of King Nabu - Nasir ( 747-734 BC) are a set of Sumerian astronomical written records survived. The Babylonians calculated on the basis of their extensive long-term data collections, the orbital period of the solar and lunar eclipses, known under the name of Saros today, at 18 years and 11 days, respectively 6585.33 days. To start a new Saros, the earth, the sun and the moon are again almost at the same relative position.

The Babylonians were in addition to the determination of astronomical contexts of sun and moon also calculate the changes in the lunar movements and the apparent angular velocity of the sun and planets as well. These also included the ability to determine anomalistic months as a result of the ecliptic.

In the early 6th century BC they had both relative movements of the sun and moon, the lunar perigee and apogee and their nodes, as well as overlap between the lunar orbit and the ecliptic, which are responsible for the Saros cycle, determined. Around 500 BC Nabu - rimanni has corrected these values ​​with its improved observations of eclipses: He corrected the motion of the moon relative to the Sun than 10 minutes less per year, the motion of the lunar perigee greater than 20 minutes, and the movement of nodes than 5 minutes less per year. These values ​​were later continued by the astronomer Kidinnu improved ( the Kidenas the Greeks ). Hipparchus later used these values ​​of Kidinnu.

Nabu - rimanni developed the so-called A system, a group of ephemeris, or tables containing the positions of the moon, the sun and the planets at any given time. Based on the observations of several centuries, these tables were still a bit rough and were overtaken than a century later by the system B of Kidinnu. Nabu - rimanni summarized his work together in a book about the Akkadian observations of the moon and the stars.

Nabu - rimanni determined the solar year to 365 days, 6 hours, 15 minutes and 41 seconds. He used a water clock to measure the days, the months and the length of the solar year. He calculated the length of the synodic month 29d 12h 44m 5.05s or 29.530614d, compared with the modern value 29d 12h 44m 3.49s or 29.530596d with an error of 1.56 s He had also shown how an apparent strength of a lunar eclipse from the deviation of the lunar nodes can be determined.