Download Section 14.3 The Inner Planets

The Inner Planets
Mercury, Venus, Earth, Mars
The Inner Planets
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The four inner
planets are small
and have rocky
surfaces
They are also known
as the terrestrial
planets
The four inner
planets are Mercury,
Venus, Earth, and
Mars
Mercury
Planet closest to the sun
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Exploring Mercury
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Hard to see because it is so close
to the sun
Looks like the moon, with many
craters and flat plains
Mercury’s Atmosphere
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Extremely thin
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Heat from the sun has dissipated
the atmosphere
Also has weak gravitational force
Gas is mostly sodium
Planet of Extremes
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Greatest temperature range of all
the planets
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-183° C (-298° F) during the night
427° C (800° F) during the day
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“The Morning Star”
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7.5 earth months to revolve around the
sun
Day is longer than it’s year (8 months)
Retrograde rotation (rotating backwards)
– Hypothesis that Venus was struck by a
very large object that changed it’s
rotation
Venus’s Atmosphere
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Not a star, it reflects the light from the
sun
Venus’s Movement
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Venus
Pressure is 90 times greater than Earth’s
atmosphere
Mostly carbon dioxide
Sulfuric acid clouds
467° C (872° F) at surface (melts lead) –
caused by greenhouse effect (trapping of
heat by atmosphere)
Exploring Venus
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Covered with rock, volcanoes with lava
flows, craters (like Earth)
Features discovered by using space
probes
Rotation
Direct and Retrograde Rotations
Direct rotation (on the left) and retrograde rotation (on the right).
In direct rotation, the rotation of the planet is in the same direction as its orbital
motion.
In retrograde rotation, the rotation of the planet is in the opposite direction to its
orbital motion.
The Morning and Evening “Star”
Earth
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Atmosphere
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Extends more than
100 km above the
surface
20% oxygen / 78%
nitrogen / 2% other
Surface
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70% covered with
water
Three layers below
Earth’s rocky crust –
mantel, outer core,
inner core
Layers of the earth
Mars
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“The Red Planet”
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Reddish tinge when you see it
in the sky
Atmosphere
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Mostly carbon dioxide
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1% of the pressure of Earth’s
atmosphere
Canals on Mars?
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Giovanni Schiaparelli (1877)
discovered channels on Mars
surface
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Percival Lowell (1890)
convinced many people that
channels were built by
Martians to carry water
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Not correct, it’s an illusion, no
life known on Mars
Mars
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Seasons on Mars
Tilted axis, therefore seasons
As seasons change, dust blows
and creates dark regions on the
planet, they are not plants
Exploring Mars
Covered with craters, like the moon
Rusty dust surface (gives it it’s red
surface)
No oceans or even puddles of
water, but water did flow millions of
years ago
There is ice on the poles (water and
carbon dioxide)
The face
Olympus Mons
The Moons of Mars
Phobos (Fear)
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Largest moon (27km in
diameter)
Deimos (Panic)
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15km in diameter
Your extra credit assignment:
To research the numbers given
in this song to see if they are
scientifically plausible or were
they fabricated for the sake of
a humorous song?