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Ptolemaeus

Ptolemaeus, often rendered Ptolemy in English, is the Latinized name of Claudius Ptolemaeus, a Greco-Egyptian scholar active in Alexandria during the Roman era in the 2nd century CE. He is best known for his contributions to astronomy, geography, and mathematics, and his work shaped scientific thought for more than a millennium.

In astronomy, his major surviving work is the Almagest (Greek Megale Syntaxis), a comprehensive treatise that

In geography, Ptolemy authored Geography (Geographia), a compilation of coordinates and descriptions of about 360+ places,

In astrology, the Tetrabiblos (Quadripartite on the prognostication of events) offered mathematical methods for casting horoscopes,

Legacy and influence: Ptolemy’s geocentric framework, known as the Ptolemaic system, dominated astronomical thought in the

systematized
the
geocentric
model
of
the
cosmos.
The
Almagest
explains
the
apparent
motions
of
the
Sun,
Moon,
and
planets
through
a
system
of
deferents
and
epicycles,
and
introduces
the
use
of
an
equant
to
account
for
planetary
speeds.
It
also
contains
a
star
catalog
of
about
1,022
entries
and
serves
as
the
authoritative
reference
for
medieval
and
early
modern
astronomy.
using
a
grid-based
system
that
advanced
cartographic
technique
and
influenced
mapmaking
for
centuries,
including
Renaissance
discoveries.
contributing
to
the
medieval
and
Islamic
traditions
of
astrological
study.
Western
and
Islamic
worlds
until
the
Copernican
revolution.
His
geographical
and
mathematical
methods
informed
later
cartography
and
astronomy.
The
name
Ptolemaeus
persists
in
the
Latin
form
used
in
historical
and
scientific
contexts,
and
the
Moon’s
crater
Ptolemaeus
commemorates
his
lasting
impact.