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1. UNIQUENESS OF THE
EARTH
GEORGE LEBO
3 March 2012

2. LOCATION
THE RIGHT GALAXY CLUSTER
Can’t be in a rich cluster: Mergers and
collisions will be too frequent
Must have nearby dwarf galaxies to
supply gas and dust that maintains
the Milky Way’s spiral structure

3. The Local Group
Within 500,000 Light Years

4. The Local Group
Within 5 Million Light Years

5. LOCATION
THE RIGHT GALAXY TYPE
Must be a spiral galaxy: only 5% are spiral, the rest
are elliptical or irregular
Elliptical galaxies have no dust and gas, hence no
heavy elements out of which to make life
supporting planets.
Large irregular galaxies have active nuclei whose
radiation would exterminate life. Small irregular
galaxies have insufficient heavy elements to
support life.

6. LOCATION
RIGHT LOCATION IN THE GALAXY
Must be near, but not in, a spiral arm. We are at a co-
rotation point far from our galactic center. Note: At
the co-rotation point the Sun remains stationary and
out of a spiral arm.
Most all stars in the Milky Way are in the central bulge,
a globular cluster or a spiral arm. In each of these
locations the star densities are too high – the
planetary orbits would be unstable.

7. THE RIGHT STAR
Must be one and only one star – Gravity from
two or more stars would make stable
planetary orbits impossible. If no star (planet
was thrown out of planetary system) there
would be no energy source.
Must be a G-type star: If hotter, UV would
extinguish life: If cooler, would have to be so
close that tidal effects of the star on the
planet would slow the planet’s rotation.

8. THE RIGHT PLANET
• MUST BE IN THE HABITABLE ZONE (Water at the triple point),
distance within 2%
• MUST HAVE THE RIGHT SURFACE GRAVITY – If too high,
hydrogen and helium would be retained – If too low, the
atmosphere would dissipate into space (within 2%)
• MUST HAVE THE RIGHT ROTATIONAL PERIOD – If too fast,
circulational weather pattern would be too severe – If too slow,
the day/night temperature variation would be too great
• MUST HAVE A MAGNETIC FIELD – Needed for protection from the
Solar wind
• MUST HAVE A CENTRAL HEAT SOURCE (AN UNUSUALLY
LARGE CORE) TO DRIVE TECTONIC ACTIVITY – The
Earth’s surface would erode to the extent that life would not
survive unless the Earth’s crust was constantly replenished.
• MUST HAVE WATER (OR SOME OTHER LIQUID) – To lubricate
the tectonic activity

9. THE RIGHT PLANETARY
COMPANIONS
• NEED A GIANT OUTER PLANET LIKE
JUPITER – It takes the hit from asteroids
and comets eliminating catastrophes on
Earth
• NEED A LARGE MOON IN ORDER TO:
Stabilize the Earth’s axial tilt
Create tides which wash the Earth’s surface
cleansing the oceans and mixing
oxygen from the air into the water to
support marine life.

10. SHORT LIST OF EARTH’S UNIQUE PARAMETERS
• GALAXY CLUSTER TYPE
• GALAXY SIZE
• GALAXY TYPE
• GALAXY LOCATION
• PARENT STAR’S DISTANCE FROM
GALACTIC CENTER
• PARENT STAR’S DISTANCE FROM
CLOSEST SPIRAL ARM
• NUMBER OF STARS IN PLANETARY
SYSTEM
• PARENT STAR BIRTH DATE
• PARENT STAR AGE
• PARENT STAR MASS
• PARENT STAR METALLICITY (HEAVY
ELEMENTS)
• PARENT STAR COLOR
• ESCAPE VELOCITY
• DISTANCE FROM PARENT STAR
• ORBITAL ECCENTRICITY
• AXIAL TILT
• ROTATION PERIOD
• MAGNETIC FIELD
• ALBEDO
• MASS OF “GREAT COLLIDER”
• TIMING OF “GREAT COLLIDER”
• SPEED OF “GREAT COLLIDER”
• COLLISION ANGLE OF “GREAT
COLLIDER”
• CO2 LEVEL IN ATMOSPHERE
• O2 QUANTITY IN ATMOSPHERE
• H20 LEVEL IN ATMOSPHERE
• O3 LEVEL IN ATMOSPHERE
• SEISMIC ACTIVITY
• GRAVITATIONAL INTERACTION
WITH MOON
• JUPITER DISTANCE
• JUPITER MASS
• ATMOSPHERIC PRESSURE
• ATMOSPHERIC TRANSPARENCY

11. SUMMARY
• EARTH HAS SOME UNIQUE
CHARACTERISTICS
• HUGH ROSS LISTS 322 SUCH PARAMETERS
• HE PLACES A PROBABILITY OF
APPROXIMATELY ONE IN 10
-304
IN FINDING
ANOTHER PLANET LIKE EARTH IN THE
UNIVERSE IF THERE ARE 10
22
PLANETS
(ONE PER STAR)
• http://www.reasons.org/articles/probability-
for-life-on-earth-apr-2004
• ADMITEDLY THIS IS ROSS’ OPINION