N one of the other worlds in our solar system look
like Earth.
When I was orbiting our planet in the Space
Shuttle, I would often float over to a window and gaze
down at the sparkling blue oceans, billowing white
clouds, and rugged mountaintops of the Earth below.
The signs of life are everywhere. A patchwork of fertile
farmland lines the lazy Mississippi River, vast blooms
of phytoplankton color the coastal waters of Southern
Africa, and glittering coral reefs circle the islands of the
Caribbean. At night, Earth’s continents are outlined
by twinkling city lights. Our planet is truly an oasis
in space.
The view from space shows us how different Earth
is from the other planets, but it also shows that many
of the same processes that shape other worlds—wind
and weather, impacts and volcanism—shape our
planet, too. Through the Shuttle window, I watched
an enormous dust storm grow until it blotted out all
of Northern Africa. I saw the eroded remnants of an
ancient impact crater in Eastern Canada, looked along
a chain of volcanic islands in the Pacific Ocean, and
gazed into a gaping rift valley in East Africa.
Imagine what it would be like to orbit an alien
world: to watch a giant dust storm sweep across the
ancient highlands of Mars, or look down on the
slumping impact craters of Callisto, or see the gushing
ice geysers of Triton. What would it be like to
swing past Titan with Voyager 1, ride with Giotto
past the icy heart of Halley’s Comet, or wander
with Sojourner across an ancient Martian floodplain?
Though astronauts have never traveled beyond our
own moon, humankind can now see the magnificent
rings of Saturn, the tortured surface of Io, and the
stormy atmosphere of Neptune through the eyes of
robotic spacecraft.
Before the dawn of the Space Age, our instruments
were confined to Earth’s surface. Telescopes strained
to gather light from worlds that were hundreds of
millions of miles away. Even the most powerful produced
fuzzy images of the planets, and only whetted
scientists’ appetites for more detailed observations.
Then, in 1957 the Soviet Union launched the world’s
first satellite into orbit around Earth. Sputnik rocketed
the world into the Space Age, and ignited a race between
the United States and the Soviet Union for space
superiority, the most public aspect of which was the
race to the Moon. These new technical capabilities
also stimulated the robotic exploration of our solar
system, exploration that would continue long after Neil
Armstrong left his bootprints in the lunar soil.
Today, spacecraft have visited every planet except
Pluto. The Ulysses spacecraft circled above the poles
of the Sun; Venera plunged headlong into the crushing
carbon dioxide atmosphere of Venus; Vikings scooped
up soil from the dusty red surface of Mars; and Galileo
photographed barren, battered asteroids during its
long journey to Jupiter. As these robot explorers radioed
images and data back to Earth, they changed
our view of the solar system forever.