Download The Goldilocks Planet

GOLDILOCKS STORIES
Once upon a time, there was a little girl named Goldilocks. She went for
a walk in the forest. Pretty soon she came upon a house. She knocked
and, when no one answered, she walked right in. At the table in the
kitchen, there were three bowls of porridge. Goldilocks was hungry.
She tasted the porridge from the first bowl.
"This porridge is too hot!" she exclaimed.
So, she went to the second bowl.
"This porridge is too cold," she said
So, she tasted the last bowl of porridge.
"Ahhh, this porridge is just right,"
she said happily and she ate it all up.
"Goldilocks" is a fairy tale first recorded in narrative
form by British author and poet Robert Southey, and
first published anonymously in a volume of his
writings in 1837.
The Goldilocks condition of ?Just Right” has become a popular, pseudo-scientific expression for environmental
attributes that are perfectly matched to the assumed ulterior needs of its dependants. When looking for the ideal
environmental requirements to support life, Earth was ?just right”. Looking around the solar system Mercury
and Venus are too hot, Mars and the outer planets too cold. Only Earth seems to be just right for life. Our planet
has liquid water, a breathable atmosphere, a suitable amount of sunshine. Perfect. If Earth were a little closer to
the sun it might be hot like choking Venus; a little farther out, cold like arid Mars. Somehow, though, we ended
up in just the right place with just the right ingredients for life to flourish. Researchers of the 1970s scratched
their heads and said we were in "the Goldilocks Zone." But the Goldilocks Zone seemed a remarkably small
region of space. It didn't even include the whole Earth. All life known in those days was confined to certain
limits: no colder than Antarctica (penguins), no hotter than scalding water (desert lizards), no higher than the
clouds (eagles), no lower than a few mines (deep mine microbes).
In the past 30 years, however, our knowledge of life in extreme environments has exploded. Scientists have
found microbes in nuclear reactors, microbes that love acid, microbes that swim in boiling-hot water. Whole
ecosystems have been discovered around deep sea vents, where sunlight never reaches and the emerging
vent-water is hot enough to melt lead. The Goldilocks Zone is bigger than we thought! Mono Lake in
California is an extremely salty and alkaline body of water, formed
some 760,000 years ago in a basin that has no outlet to the ocean.
Because it lacks an outlet, dissolved salts make the lake very alkaline
and saline. It is almost 3 times saltier than sea water and has a pH of 10,
about the same as WindexTM, a household glass cleaner. (For
comparison, a pH of 7 is neutral; 14 corresponds to pure lye.)
Surprisingly, though, Mono Lake supports a wide array of life from
microbes, to plankton, to small shrimp. T californiensis is right at home
there. It thrives in highly alkaline conditions (pH 8-10.5) and at salt
concentrations near 20%. And there are more. Finding new species in
this adverse environment is a detective story worthy of Perry Mason or
Hercule Poirot. Maybe primitive life will evolve and adapt to almost any
environmental conditions. Or manufacture an environment to suit its
needs? Earth’s anaerobic bacteria evolved the ability to utilise the poisonous oxygen atmosphere!
So, when astronomers talk about a ?Goldilocks Planet” what are its parameters? The planet should be as
close as possible to what the Earth is: Its mass should be between 0.5 and 5 Earth-masses; It must have liquid
water, preferably some solid surfaces; it must have an atmosphere, a temperate zone between 0 and 50 degrees;
sunshine, seasons and a magnetic field. Perhaps a Goldilocks planet also needs volcanic activity and continental
drift to re-cycle its surface. A combination of these ?just right” requirements can only be found in a narrow zone
around a parent star of sun-like proportions. That zone is naturally called the Goldilocks Zone.
70 Virginis was one of the first stars confirmed to have planets orbiting it. 70 Virginis b (abbreviated 70 Vir b)
is an extrasolar planet approximately 60 light-years away in the constellation of Virgo. Discovered in 1996 by
Geoffrey Marcy and R. Paul Butler, 70 Virginis b was considered to be within its star's habitable zone (the
"Goldilocks zone"), but it was later confirmed that the planet has a too eccentric 116 day orbit and a mass 7.5
times the mass of Jupiter. Its surface gravity is expected to be about six to eight times that of Jupiter's. The
Hipparcos satellite later also showed that the star was more distant than first thought and
therefore brighter, resulting in the planet being too hot to be in the habitable zone. In
astronomy, the habitable zone is the distance from a star where an Earth-like planet can
maintain liquid water on its surface and potentially therefore Earth-like life. The
habitable zone is the intersection of two regions that must both be favourable to life: one
within a planetary system, and the other within a galaxy. Planets and moons in these
regions are the likeliest candidates to be habitable and thus capable in theory of bearing
extraterrestrial life similar to our own. The habitable zone is not to be confused with the
planetary habitability. While planetary habitability deals solely with the planetary
conditions required to maintain carbon-based life, the habitable zone deals with the
stellar conditions required to maintain carbon-based life, and these two factors are
not meant to be interchanged..
The concept "Habitable zone" is used also at a selection of target stars during
transmission of interstellar radio messages (IRMs) under SETI project METI
(Messaging to Extra-Terrestrial Intelligence). For example, ?A Message From Earth”
and ?Hello From Earth” have been sent to the star Gliese 581 because this star has its
own planetary system and one of its planets is situated in a habitable zone.
Goldilocks planets are of key interest to researchers looking either for existing (and
possibly intelligent) life or for future homes for the human race. Finding Earth-sized
Goldilocks planets is a key part of the Kepler Space Mission, which uses a space
telescope (launched on 7 March 2009) to survey and compile the characteristics of
habitable-zone planets. As we heard before Kepler has so far discovered 1,235 possible
planets, with 54 of those candidates located within the Goldilocks zone.
The Drake equation (which was the subject of a previous session) attempts to estimate A representation of the
1679-bit Arecibo message.
the likelihood of non-terrestrial intelligent life and incorporates a factor (ne) for the
average number of life-supporting planets in a star system with planets. The discovery of extrasolar Goldilocks
planets helps to refine estimates for this figure. Very low estimates would contribute to the Rare Earth
hypothesis, which posits that a series of extremely unlikely events and conditions led to the rise of life on
Earth. High estimates would reinforce the Copernican mediocrity principle, in that large numbers of
Goldilocks planets would imply that Earth is not especially exceptional.
A 2007 non-fiction book by physicist and cosmologist Paul Davies, describes the idea
of a fine-tuned Universe. Cosmic Jackpot, with the subtitle The Goldilocks Enigma,
asks the question: Why is the Universe Just Right for Life? Davies argues that certain
universal fundamental physical constants are precisely adjusted to make life in the
Universe possible: that we have, in a sense, won a "cosmic jackpot," and that conditions
are "just right" for life, as in the Story of the Three Bears. He maintains that there is now
broad agreement among physicists and cosmologists that the universe is in several
respects 'fine-tuned' for life. Explaining this enigma, Davies discusses possible
solutions, such as the anthropic principle, the idea of a multiverse, which contains many
different universes (including our "just right" one), and the idea of intelligent design.
Davies also discusses a number of other ideas connected with the "multiverse." Much
like a pencil falling to the ground from its tip in a trade off of symmetry for stability, he
writes that the Big Bang could have established a complex but stable universe from symmetry breaking, as the
heat radiation in "space" lowered abruptly past the Curie Point. (In physics the Curie Point is the temperature at
which a ferromagnetic material becomes paramagnetic. A magnet will lose its magnetism if heated above the
Curie temperature; the effect is reversible. It is named after Pierre Curie.) An everyday example of this you may
have met is the temperature controlled soldering iron.
Much of the current Space Exploration efforts are directed towards improving our understanding of the role of
Life in the Cosmos. NASA's Mars Science Laboratory spacecraft with the new Curiosity rover is due to launch
aboard an Atlas V rocket on Nov. 25, 2011 from Space Launch Complex 41 at Cape Canaveral. The Curiosity
rover (twice as big and complex as Spirit and Opportunity) is set to continue the search for biological markers
on Mars. Can biology be explained purely with physics or chemistry. Is life on Earth, are we, unique in the
Universe? Is the emergence of life a new (late) stage in the cosmic evolution?
Rovers on Mars and the Anthropic Principle (the philosophy that the physical Universe must be compatible
with the conscious life that observes it) are two subjects we will talk about in our program for 2012.
AK