Hipparchus and Trigonometry
Hipparchus founded
trigonometry, by computing
the first trigonometric
function, namely, a chord
tables.
Hipparchus on a Poem
The sole surviving work of
Hipparchus is known as the
Commentary on the Phenomena of
Aratus and Eudoxus.
It described a calendar with
references to the risings and settings
of constellations.
Life
Hipparchus is mainly known from
Ptolemy’s Alagest. He is also known by
Strabo’s Geographia and also from
Pliny’s Naturalis Historia.
He was born in Nicaea, which is
present day Turkey.
Hipparchus must have lived
sometime after 127 BC.
Life
Hipparchus is believed to have died on the
island of Rhode, where he spent most of his
later life.
The main original works of Hipparchus have
been lost over the year. It is known that he
created a celestial globe.
There are 2nd and 3rd centuries coins made in
Hipparchus’ honor in Bithynia.
Life
Hipparchus is recognized as the originator
and fathor of astronomy. It is believed that
Ptolemy originated his idea’s from
Hipparchus’ and just perfected them.
Accomplishments
Hipparchus is known for many things:
-Astronomical instruments and astrometry
-Geography
-Star catalogue
-Lunar and solar theory
-Geometry and Trigonometry
Geometry and Trigonometry
Hipparchus is the first recognized mathematician
who complied a Trigonometry table. He used this
table to compute the behavior of the orbits of the
Moon and the Sun.
He described this behavior in the [chord(A) =
sin(A/2)] equation.
He explained his work in a now lost, Toon en
kuklooi euteioon (Of Lines Inside a Circle).
Lunar and Solar Theory
Hipparchus studied and had theories over:
-Motion of the Moon
-Orbit of the Moon
-Apparent motion of the Sun
-Orbit of the Sun
-Distance and sizes of the Moon and Sun
-Eclipses
Astronomical Instruments and
Astrometry
Hipparchus invented and improved many
astronomical instruments, which were used for nakedeye observations.
He invented the astrolabe, which was to measure the
geographical latitude and time by observing stars.
He also invented a dipotra, which measured the
apparent diameter of the sun and moon. It was a 4foot rod with a scale, a sighting hole at one end and a
a wedge that could be moved along the rod to exactly
obscure the disk of the Sun or the Moon.
Geography
Hipparchus was the first to apply mathematical rigor to the
determination of the latitude and longitude of places on the
Earth.
He also made detailed corrections to the locations and
distances mentioned by Eratosthenes.
Star Catalogue
Hipparchus created a catalogue with the
coordinates of about 1,000 stars.
In this sculpture, the atlas the man is holding
features the positions of the stars, is from
Hipparchus’ star catalogue.
Conclusion
The Greek Astronomer Hipparchus is credited with
introducing numerical data from observations into
geometric models and discovering the precession
of the equinoxes. Little of his work survives, but
Ptolemy considered him his most important
predecessor.