8.1 Four Main Processes Shape
the Inner Planets
The past 55 years have been an exciting time of exploration
and discovery about Earth and its sibling worlds. Robotic
probes visited every classical planet, and astronauts
walked on the surface of the Moon. In addition to discoveries
from the new space missions and telescopes, improved
analysis techniques of the rocks and soil brought
back from the Moon more than 40 years ago have led
to some surprising new
results. The information
from these missions has
revolutionized the understanding
of the Solar
System