The Terrestrial Planets
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Transcript The Terrestrial Planets
The Terrestrial
Planets
Chapter 23, Section 2
Mercury: The Innermost Planet
Mercury, the innermost and smallest planet (not
counting Pluto), is hardly larger than Earth’s moon
and is smaller than 3 other moons in the solar
system
Mercury has no atmosphere, and reflects only 6% of
sunlight that hits it
There are cratered highlands, and some smooth
terrains
It is a very dense planet, suggesting a large iron core
Mercury revolves around the sun quickly, but it
rotates slowly (1 Mercury day = 59 Earth days), so a
night on Mercury (-173ºC) lasts for three months and
a day (427ºC) lasts for three months
Mercury has the greatest temperature extremes of
any planet
Mercury
Venus: The Veiled Planet
Venus orbits the sun in a nearly perfect circle
every 255 Earth-days
Venus is covered in thick clouds that visible
light cannot penetrate, instead we use radar to
view topography
Basaltic volcanism and tectonic activity shape
Venus’s surface
Based on the low density of impact craters,
these forces must have been very active during
the recent geologic past
On Venus, the greenhouse effect has heated
the planet’s atmosphere to 475ºC; the main
reason for the runaway greenhouse effect is
that Venus’s atmosphere consists of 97%
carbon dioxide
Venus
Mars: The Red Planet
The Martian atmosphere has only 1% the density of Earth’s
and is made primarily of carbon dioxide with some water
vapor
Although the atmosphere of Mars is very thin, extensive
dust storms occur and may cause the color changes
observed from Earth
Hurricane-force winds up to 270 kilometers per hour can
persist for weeks
Mars’ northern hemisphere contains several volcanoes
(Olympus Mons is the size of Ohio and is 2 ½ times larger
than Mt. Everest)
The southern hemisphere is dominated by a large canyon
called Valles Marineris
Some areas of Mars exhibit drainage patterns similar to
those created by streams on Earth (water = life)
The present Martian atmosphere only contains trace
amounts of water
Mars
Assignment
Read Chapter 23, Section 2 (pg. 649-653)
Do Section 23.2 Assessment #1-6 (pg. 653)