Caption: A detail of the "The School of Athens" (1509--1511) by Raphael (1483--1520) showing by probable identification, left to right, Hipparchus (c.190--c.120 BCE), Ptolemy (c.100--c.170 CE), Apelles (fl. 4th century BCE) (for whom the model is thought to be Raphael himself) and Protogenes (fl. 4th century BCE) (for whom the model may be Il Sodoma (1477--1549)).

Features:

1. The identification of the figures in the detail are uncertain (see Wikipedia: The School of Athens: Figures).

   However, the identification of Hipparchus seems likely to yours truly since he's holding a celestial globe and he's facing a figure holding a globe (and a reasonably accurate one too for a cartoon circa 1509--1511) and wearing a crown who must Ptolemy (c.100--c.170 CE)---Ptolemy was a geographer as well as an astronomer and is often shown wearing a crown because the Middle Ages and Renaissance tended assimilate him to the Ptolemaic dynasty that ruled Hellenistic Eygpt---Cleopatra (69--30 BCE) was the last monarch and last queen of the Ptolemaic dynasty.

2. The identification of the model for the third figure as Raphael seems pretty certain.

3. Hipparchus (c.190--120 BCE) is considered the greatest observational astronomer of Greco-Roman antiquity. He did mathematical astronomy too. His personal contributions CANNOT be fully disentangled from those of his much later successor Ptolemy (c.100--c.170 CE).

4. Hipparchus' greatest discovery was the discovery of the axial precession (AKA precession of the equinoxes) (see Wikipedia: Hipparchus: Precession of the equinoxes).

   Hipparchus did NOT, of course understand the physics of the axial precession NOR even the geometry since he was geocentrist, but he could measure the difference between the sidereal year = 365.256363004 days (J2000) and the solar year = 365.2421897 days (J2000) by observing the motion of the Sun on the celestial sphere.