March 24, 2014
The search for Earth-like planets is reaching a fever-pitch.
the evidence so far help shed light on the ancient question: Is the
galaxy filled with life, or is Earth just a beautiful, lonely
aberration? If things don't work out on this planet or if our itch to
explore becomes unbearable at some point in the future Astronomers
have recently found out what kind of galactic real estate might be
available to us.
Well have to develop advanced transport to land
there, 20 light years away.
The question right now: is it worth the
If things don't work out on this planet... or if our itch to explore becomes unbearable at some point in the
future..., astronomers have recently found out what kind of galactic real
estate might be available to us.
We'll have to develop advanced transport to land there, 20 light
years away... But that's for later.
The question right now: is it worth the trip? The destination is a
star that you can't see with your naked eye, in the southern
constellation Libra, called
Identified over 40 years ago by the German astronomer Wilhelm Gliese,
it's a red dwarf with 31% of the Sun's mass... and only 1.3% of its
Until recently, the so-called
M Stars like Gliese 581 flew below the
radar of planet hunters.
They give off so little energy that a planet would have to orbit
dangerously close just to get enough heat.
Now, these unlikely realms are beginning to show some promise... as
their dim light yields to precision technologies... as well as supercomputers... honed in the battle to understand
global changes on this planet... Earth.
Will we now begin to detect signs of alien life?
Or will these worlds, and the galaxy itself, turn out to be
lifeless... and Earth, just a beautiful, lonely aberration?
To some, like astronomer and author
Carl Sagan, the sheer number and
diversity of stars makes it, as he said,
"far more likely that the
universe is brimming over with life."
This so-called "many worlds" view can be traced back to ancient
observers... in China, India, Greece and Egypt. The Qur'an, the
Talmud, and many Hindu texts all imagined a universe full of living
In the 16th Century, this view got a boost from astronomer and
mathematician Nikolas Copernicus... who came to believe that Earth
is not the center of the universe, but revolves around the Sun.
Seven decades after Copernicus,
Galileo Galilei used his newly
developed telescope to show that our Sun was just one among
countless other stars in the universe.
By the modern era, the "many worlds" view held sway in scientific
circles. A variety of thinkers considered what and who inhabited
worlds beyond our own.
From Martians desperate to get off their planet... to alien invaders
intent on launching pre-emptive strikes against ours... or simple
life forms on an evolutionary track to complexity.
But other thinkers have been struck by a different view.
The Greek philosophers Aristotle and Ptolemy believed that humans
and Earth are unique.
With the spread of christianity, this Ptolemaic system became widely
The latest variation on this theme is what's called the "Rare Earth"
hypothesis. It holds that Earth and sophisticated life were the
result of fortuitous circumstances that may not be easy to find
again in our galaxy.
Does the current search for planets shed light on this debate...
sending it in one direction or the other?
So far, our only good reference for recognizing an Earth-like planet
It does have some fortuitous characteristics... it's dense, it's
rocky - with a complex make-up of minerals and organic compounds -
and it has lots and lots of water.
It's also got a nearly circular orbit around the Sun, at a distance
that allows liquid water to flow... not too close and not too far
away, in the so-called "Habitable Zone."
That's defined as the range of distance from a parent star that a
planet would need to maintain surface temperatures between the
freezing and boiling points of water.
Of course, that depends on the size of the planet, the make-up of
its atmosphere, and a host of other factors.
And whether the parent star is large, medium like the Sun or small.
Some scientists also believe we live in a "Galactic Habitable Zone."
We're close enough to the galactic center to be infused with heavy
elements generated by countless stellar explosions over the eons...
But far enough away from deadly gamma radiation that roars out of
If there is a galactic habitable zone... it's thought to lie 26,000
light years from the center... about where we are... give or take
about 6,000 light years.
For many years, the remarkable
planet-searching mission, Kepler,
gazed at a large body of 150,000 stars situated in a neighborhood
located 3,000 light years away from planet Earth.
The valuable information harvested by
this space probe has brought a critical point in this lengthy
for earthlike planets.
Is planet Earth one of many life-supporting
worlds scattered across the galaxy?
Or is it a unique garden of Eden
in a desolate universe?
What are we discovering about our place in the universe, from the
hunt for planets similar to Earth?
Thousands of years ago, humans
began to migrate across the planet, following mysterious roadways,
traversing unfathomable distances.
We followed all coastlines, and crossed
We managed to cross the ocean's narrow passages depleted by the last
ice age. Into every obscure part of Earth we went, looking for a
land to put down our roots, to take care of our families, or just to
discover what was there.
Today, it's the unexplored universe that
excites our imagination. With countless of stars in just one
ordinary galaxy, such as the Milky Way, we make a logical
the universe must be packed with earthlike worlds,
with life... even with humanlike life.
This supposed "many worlds" hypothesis dates back to age-old times,
to China, India, Greece and Egypt.
The Qur'an, the Talmud, and many Hindu
texts all fancied a cosmos full of live forms. It wasn't until the
16th century that this belief became grounded in the solid concepts
of the physical universe.
Astronomer and mathematician Nicolaus Copernicus asserted
that Earth revolves around the Sun.
That paved the way for the
Giordano Bruno, a natural
philosopher who assumed that the universe is everlasting and
endless. He claimed that there is a myriad of worlds with various
life forms, intelligent beings included.
to church dogma got him put to death in the year 1600.
His main ideas were proven when
Galileo Galilei used his telescope to demonstrate that our Sun
is just one among innumerable other stars.