Drawings of the moon as seen with Galileo's telescope.
By his own account, Galileo first observed the Moon on November 30
1609. Comparing patterns of light and
shadow in the vicinity of the terminator (dividing line between
light and shadow)
at first and third quarter, Galileo could argue convincingly that
there exists mountains and valleys on the lunar surface.
Aristotelian doctrine stipulated that celestial bodies were
perfectly smooth and spherical.
Drawing reproduced from Galileo's 1610 Sidereus Nuncius
The first
telescopic observations of the Moon on record were carried
out by the englishman
Thomas Harriot (ca. 1560-1621),
on the evening of
July 26 1609.
However,
based on his extant correspondence as well as entries in his notebooks,
as in the case of sunspots Harriot did not appear to have
drawn any particular physical significance from what he saw.
Bibliography:
Galileo, G. 1610, Sidereus Nuncius, trans. A. Van Helden 1989,
The University of Chicago Press.
Whitaker, E.A. 1978, Journal for the History of Astronomy,
9, 155-169
Galileo
Harriot
Clavius
Hevelius
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