sagittarius spur/Oriun Spur
left scutum centaurus arm
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1.
Our location is far from
Our location is far from
MANY HAZ
1.
Proximity to the Sun allowing liquid water.
This
is essentially the
greens-fee for any form of life in the universe. Yes, it's possible
that life can exist
without water but those ideas are purely theoretical and no empirical
evidence
exists to support the assumption.
2.
The size and composition of Earth as a Rocky Planet
Given
some recent studies of
distant stars and the on-going discovery of exoplanets, many planets
in the
universe appear to be gas-giants similar to Saturn, Jupiter, Uranus
and
Neptune. While there are also theories to imagine life on gas planets,
the
current science indicates that a rocky planet offers the best
foundation for
life and especially the diversity of life.
3.
Stability of Earth's atmosphere and chemical composition.
An
atmosphere appears to be
critical to life whether it be a gaseous atmosphere on the surface of
the
planet, or a saturated atmosphere such as the Earth's oceans, seas,
lakes and
rivers. The chemical composition and
density is also important. Mars has a
very thin atmosphere and the ability of an organism to derive
sustenance from
the scant molecules is one of the factors that makes abundant life on
Mars
problematic. Not so on earth. Our atmosphere is rich in Nitrogen,
Carbon
Dioxide, Oxygen and other compounds that create a benign atmospheric
combination.
4.
The Magnetosphere.
The
fact that Earth has a
metallic, molten core creates a magnetic field around the planet
called the Magnetosphere.
This invisible "gravity shield"
deflects radiation from the sun and space and protects organisms on
the planet
from the solar wind. Mars was once a
highly volcanic planet (an indication of a molten core), but its
volcanoes have
long-since become dormant and it appears to have a very weak and
fluctuating Magnetosphere. This may be why its atmosphere is virtually
non-existent. The solar wind simply
stripped it away without the protection of a strong and steady
Magnetosphere.
5.
Consistency of temperatures on Earth.
The
average temperature on
Venus is 462°C (864°F). On Mars it’s -60°C. (-80°F). Earth's
temperature average is 15°C. (59°F). The average temperature
on Earth not only allows liquid water to exist, but also provides a
relatively
stable environment for organisms.
Temperature extremes limit diversity of biological life forms, and
while
some bacteria can survive extremes, advanced organisms typically are
too
complex to endure the extremes.
6.
Diversity of Life.
The
Diversity of life on Earth
has two unique advantages. For one it
creates a food-chain that can sustain a variety of species allowing
for greater
evolutionary development. This is
important given the statistical inevitability of catastrophic events
on any
planet. In fact, the diversity of life
on Earth may be the only reason life on Earth has continued after the
extinction of 65% of all species including the dinosaurs 65 million
years ago
due to an asteroid impact, and nearly 95% of all species 250 million
years ago
due to a massive series of volcanic eruptions across what is now
Siberia.
7.
Earth's moon.
Our moon has a remarkable, stabilizing
affect on our planet. Without the
moon, the rotation of the Earth would result in a day that averages
about 4
hours. The moon has slowed us down to a
comfortable 24 hours and has also stabilized Earth's rotation on its
axis. The moon also creates tides which is believed
to have created an evolution machine in the tide-pools and tidal-zone
between
land and sea. This repeated tidal action
is thought to have encouraged evolution as animals on the shore slowly
became
accustomed to a daily land and sea environment allowing them
ultimately emerge
onto the land.
8.
Stability of the Sun as a star.
Our
sun is actually a very
average star in terms of size and activity.
That's a good thing. That means
the radiant heat and radiation is typically consistent although
occasional
solar flares do show up to send out bursts of radiation. Fortunately
we have survived those rare
bursts for thousands of years. Our sun
is also a solitary star. It's believed
that 85%
of
stars in the Milky Way are binary stars.
It's interesting to think about two stars orbiting each other, but for
planets in a solar system the gravitational forces would wreck havoc
on the
planets and probably cast asteroids and comets around like shot from a
shotgun.
9.
The Ozone Layer.
We hear about the Ozone layer all the time. In fact, we now know there are recurring holes in the Ozone at the north and south poles. Ozone is much like the Magnetosphere. It's another buffer against solar radiation especially Ultra-violet (UV) radiation and is another result of our dense and complex atmosphere. Even though many planets may have a robust and dense atmosphere, the existence of an Ozone layer and the function it performs as a radiation shield is most likely rare and unique.
10. The
amount of water on
earth.
Water
on a planet is a great
way to give life a head start. But you
need more than a puddle. Some theories
postulate that the water
on earth was largely due to icy, comet collisions during the late
heavy-bombardment 3.3 to 4.5 million years ago.
The result was essentially a water planet with less land than sea. If
water is the wellspring of life, Earth has
more than enough.
11. Jupiter
as a Solar System
vacuum cleaner for asteroids, comets, and meteors.
Astronomers
watched in
amazement as the comet Shoemaker-Levy broke into 9 pieces and slammed
into
Jupiter in 1994. The impact on the
planet was frightening and a reminder of Jupiter's value in our Solar
System. In many respects, its immense gravitational
field acts like a system wide vacuum cleaner attracting rogue
asteroids, comets
and meteors to its surface and away from other planets including
Earth.
12. The
stability of the solar
system.
3.3
to 4.5 millions years ago,
our Solar System was a highly unstable environment. The orbits of the
gas giants on the outer rim
of our Solar System were closer and not as concentric resulting in a
maelstrom
of rocky debris and icy comets in constant collision across the
planets. Any life at that time didn't stand a chance
beyond the most resilient and buried bacteria.
No doubt, there are millions and millions of solar systems enduring
the
same. Fortunately, our Solar System is
relatively stabilized in terms of planetary orbits.
13. Our
location in the Milky
Way Galaxy
Our
location in the Galaxy is at the edge of a spiral arm called the
Orion Arm,
and is about two-thirds of the way from the center of our galaxy to
the edge of
the starlight. That's a very good place
to be. Stars and systems closer to the
center of the Milky Way are in a very crowded neighbourhood where
collisions
with celestial bodies and high radiation exposure is statistically
higher. There's also the affect of that super-massive
black hole at the center of our galaxy.
Our location is a very good one that once again provides relative
stability and safety.
14. The
Stability of the
Galaxy.
Yes,
galaxies matter too. Many galaxies are in collision. In fact, the
Milky Way galaxy is on a
collision course with the much larger Andromeda galaxy in about 3
billion
years. The Milky Way galaxy is also
rather small compared to some of the giants that occupy the universe.
This too could decrease the odds of dramatic
and cataclysmic events that might take place in a dense, massive
galaxy.
15. The
Stability of our
Quantum Universe
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