Olaus Roemer
Discovering the Speed of Light
Dorna Mohaghegh
Feb 2, 2006
Just So You Know…
 Born in Denmark 1644
 Studied at the
University of
Copenhagen
 Nine years in Royal
Observatory of Paris
 Edited Tycho Brahe’s
manuscripts
 Professor of
Mathematics and
Astronomy
Discovering the Speed of Light
 Galileo attempted first and
failed
 Roemer became curious
while observing the orbit
of Jupiter’s moons
 Time elapsed between
eclipses of Jupiter's
moons became shorter as
Earth moved closer to
Jupiter and became
longer as Earth moved
farther away.
Discovering the Speed of Light
 Hypothesized a
finite speed of light
 Used known
distances of Earth
and Jupiter’s orbits
to get a rough
estimation
 2.3 x 108 m/s