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Extrasolar Earthlike Planets
Copyright © 2003 by Robert J. Sawyer
All Rights Reserved.
Nebula Award-winning science-fiction writer
Robert J. Sawyer
writes and presents a weekly science column for
the Canadian Broadcasting Corporation's CBC Radio One.
The columns, which have the umbrella title
Science FACTION: Commentaries from the Cutting Edge of Science,
are produced by Barbara Saxberg in Toronto, and
syndicated to local CBC Radio stations across Canada.
Recorded 23 June 2003
Host: Everybody knows our solar system has nine planets
in it, and we can live unaided on only one of them the
good old Earth. But what if there were other Earths?
Science-fiction writer Robert J. Sawyer looks to the heavens for
new homes for humanity.
Sound: The opening of Star Trek: "Space, the final
Robert J. Sawyer: Those are probably the most famous words
ever uttered by a Canadian. When William Shatner noted that space
was the final frontier, he couldn't have been more correct. And
if things go well in the next couple of years, we're finally
going to start opening up that frontier.
Music: Jupiter (from Holst's "The Planets")
We've already found more than a hundred planets outside our solar
system other worlds orbiting other stars. Here's how we do
it: we look at a star through a very powerful telescope and see
if it's weaving from side to side as it moves across the sky. If
it is, we infer that an unseen companion a planet
is tugging at the star while orbiting around it. The problem is
that only really big planets, like Jupiter, can make a star
visibly wobble. And Jupiter, sad to say, is not very hospitable:
it's a huge ball of gas, with crushing gravity.
Sound Effect: Running stream
Also, most of the planets we've found are too close to, or too
far away from, their suns to have liquid water, something we
believe is necessary for life. A habitable world has to orbit in
a Goldilocks zone, neither too close to the star, where it's too
hot, or too far away from the star, where it's too cold.
Now, a new technique has been devised for finding smaller
planets. In 2006, NASA will launch Kepler, a
super-sensitive space telescope that will turn an eagle eye on
thousands of stars. It'll watch to see if the light from a star
periodically dims a bit such a dimming could be caused by
a small planet passing between Kepler and the star as it
orbits around the star. In other words, this new technique will
let us find planets much smaller than those we've previously been
able to detect. Later space telescopes will do spectroscopic
analyses of the atmospheres of these little worlds, looking for
ones that are similar to Earth.
The discovery of other Earth-like planets will be as important as
the discovery of those continents we collectively refer to as
`the New World' was five hundred years ago. Such planets will
beckon to us and ultimately, we will travel to
them. It's what we've always done as a species; just as `because
it's there' was reason enough for Edmund Hillary to scale
Everest, so too will the mere presence of another inhabitable
world compel us to visit it.
And, indeed, we will eventually do more than just visit. All the
reasons that people left Europe and Asia for North America
freedom to pursue their religious beliefs, lack of economic
opportunity at home, oppressive local governments, and plain
simple adventure apply equally well to going to another
Music: Mars (from Holst's "The Planets")
Right now, we're stuck on this particular world, simply for lack
of somewhere appealing to go. Oh, Mars does indeed call out to
us, and while it's true that it's the most habitable world other
than Earth in our solar system, it's also true that it's
substantially less habitable than Antarctica. Engineers,
explorers, and scientists will go to Mars but generations
of regular folk, of immigrants looking for new opportunities,
will go to the many Earth-like worlds we will discover in the
next few years.
In the future, human beings living on well, let's call it
"Eden," the first unspoiled garden world we go to orbiting some
nearby sun those living on Eden will perhaps refer to
themselves as Earthling-Edenites, just as many people today
identify themselves as, say, Italian-Canadians: they'll
acknowledge with pride where they came from, but also accept that
their real home is the new world they've gone to.
I'm Robert J. Sawyer.
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