Assertion: greek astronomer | /r/HasProperty | hipparchus
Facets:
value: especially
type: DEGREE
Source sentences:
text: The magnitude system dates back roughly 2000 years to the Greek astronomer Hipparchus (or the Alexandrian astronomer Ptolemy—references vary) who classified stars by their apparent brightness, which they saw as size (magnitude means "bigness, size").
text: Later Greek astronomers, especially Hipparchus and Ptolemy, refined Aristarchus’s methods and arrived at very accurate values for the size and distance of the Moon.