Geoscience Reference
In-Depth Information
er Earth, its brightest part would represent the land surface while its darker part
would more appropriately represent the water surface.”
3
Galileo understood that the Moon is a rocky world with features and a history.
His lunar observations had no immediate effect on the scientific world, but another
of his discoveries did. Turning his telescope on Jupiter, so much farther away than
the Moon, Galileo first observed three bright objects near the planet, then a fourth.
As he continued to observe, he saw that the objects circle Jupiter just as the Moon
circles the Earth and, as he was coming to believe, the planets circle the Sun. This
finding emboldened Galileo to adopt Copernicus's model of a Sun-centered solar
system, a heretical conversion that came close to getting him burned at the stake.
That had been the fate of an earlier scientist, Giordano Bruno, among whose sins
was his claim that the Sun is a star and that the universe contains an infinite num-
ber of worlds populated by intelligent beings like us.
Over the centuries after Galileo, many amateur astronomers and a few profes-
sionals (who usually preferred to study stars and galaxies) turned their steadily im-
provingtelescopesontheMoon.Theyreportedastoundingfindings:asphalt,bomb
craters, coal dust, coral reefs, dust storms, glaciers, ice and snow, people (Selen-
ites), and vegetation. Many noted that while they were observing the Moon, or
in between their observations, something changed. They claimed to have seen en-
tire craters appear on the Moon and others disappear. Bright flashes and reddish
patches materialized, they reported, as if from volcanic eruptions. Fog, mist, and
haze (on the Moon) sometimes made the seeing difficult. Here was an orb that
mirrored imagination. But by 1964, the four-hundredth anniversary of Galileo's
birth, the era of anything-goes speculation about the Moon was soon to end. Al-
most everything that anyone had ever claimed, save what the Greeks had deduced
and Galileo had observed, was about to be proven wrong.
Astroblemes
Before the United States could accept President Kennedy's challenge to send men
to the Moon and return them safely to Earth within the decade of the 1960s, much
more had to be learned about the Moon's surface. Where were the safest landing
sites, if indeed there were any? Would the first astronaut to step onto the Moon
sink into a thick layer of dust? Scientists could not answer these vital questions by
peering at the Moon through telescopes: rockets had to carry cameras there for a
close-up view.
In 1961, the United States began the Ranger Program, with the goal of sending
spacecraft to the Moon to return photos of the surface by telemetry just before they