Agrippa ( el, Ἀγρίππας; ) was a

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, moons, comets and galaxies – in either ...

. The only thing that is known about him regards an astronomical observation that he made in 92 AD.

Ptolemy Claudius Ptolemy (; grc-gre, Πτολεμαῖος, ; la, Claudius Ptolemaeus; AD) was a mathematician, astronomer, astrologer, geographer, and music theorist, who wrote about a dozen scientific treatises, three of which were of importanc ...

writes that in the twelfth year of the reign of

Domitian Domitian (; la, Domitianus; 24 October 51 – 18 September 96) was a Roman emperor who reigned from 81 to 96. The son of Vespasian and the younger brother of Titus, his two predecessors on the throne, he was the last member of the Fl ...

, on the seventh day of the

Bithynia Bithynia (; Koine Greek: , ''Bithynía'') was an ancient region, kingdom and Roman province in the northwest of Asia Minor (present-day Turkey), adjoining the Sea of Marmara, the Bosporus, and the Black Sea. It bordered Mysia to the southwe ...

n month ''Metrous'', Agrippa observed the

occultation An occultation is an event that occurs when one object is hidden from the observer by another object that passes between them. The term is often used in astronomy, but can also refer to any situation in which an object in the foreground blocks ...

of a part of the

Pleiades The Pleiades (), also known as The Seven Sisters, Messier 45 and other names by different cultures, is an asterism and an open star cluster containing middle-aged, hot B-type stars in the north-west of the constellation Taurus. At a distance ...

by the southernmost part of the

Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...

. The purpose of Agrippa's observation was probably to check the

precession Precession is a change in the orientation of the rotational axis of a rotating body. In an appropriate reference frame it can be defined as a change in the first Euler angle, whereas the third Euler angle defines the rotation itself. In oth ...

of the

equinox A solar equinox is a moment in time when the Sun crosses the Earth's equator, which is to say, appears directly above the equator, rather than north or south of the equator. On the day of the equinox, the Sun appears to rise "due east" and se ...

es, which was discovered by

Hipparchus Hipparchus (; el, Ἵππαρχος, ''Hipparkhos''; BC) was a Greek astronomer, geographer, and mathematician. He is considered the founder of trigonometry, but is most famous for his incidental discovery of the precession of the e ...

. The lunar crater

Agrippa Agrippa may refer to: People Antiquity * Agrippa (mythology), semi-mythological king of Alba Longa * Agrippa (astronomer), Greek astronomer from the late 1st century * Agrippa the Skeptic, Skeptic philosopher at the end of the 1st century * Agri ...

is named after him.

References

External links

Agrippa
Ancient Greek astronomers 1st-century Greek people 1st-century births 1st-century deaths {{greece-scientist-stub