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Touring Our Solar System
Chapter 23
23.1 The Solar System
99.85% of the mass of our solar
system is in the Sun, planets
make up the rest.
Gravity holds planets in orbit.
A. Overview of the Planets
Terrestrial planets: small and
rocky
Jovian planets: huge gas giants
How long is Jupiter’s “year”?
How long is Mercury’s “year?
23.1 The Solar System
Interiors of the Planets
Classes: (based on melting
point)
gases: H and He (-273oC)
rocks: silicate and iron
(> 700oC)
ices: ammonia,
methane, carbon
dioxide, and water.
(between others)
23.1 The Solar System
Atmosphere of the
Planets
Planets can only have an
atmosphere if gravity
is great enough.
Ex: Earth: 11 km/s
escape velocity.
He and H escape from
Earth.
23.1 The Solar System
B. Formation of solar
System.
Nebular Theory
Sun and planets
formed from a
rotating disk of gas
and dust.
Planetesimals collided
and built the planets
and become round.
23.2 Terrestrial Planets
A. Mercury:
Smallest planet (no atmosphere)
Dense with many craters
Scraps from cooling
Temperature:-173 to 427oC
59 earth-day rotation
88 earth-day revolution
23.2 Terrestrial Planets
B. Venus:
255 Earth-day “year”
Thick crushing atmosphere (97%
carbon dioxide) 90x pressure
Temperture-475oC
Radar maps shows basaltic
volcanism and tectonic
activity.
Most flat plains with few
mountains.
23.2 Terrestrial Planets
C. Mars:
Polar caps made of CO2
Large long dust storms
Most atmosphere escaped
Olympus Mons- 23 km high
Valles Marineris
23.2 Terrestrial Planets
C. Mars:
Rovers discovered marks of liquid
water on Mars
23.3 Outer Planets (and Pluto)
Jupiter: Giant Among Planets
1/800 of Sun Mass
2.5x greater then all others
planets together.
Great Red Spot- seen cyclonic
storm seen Giovanni Cassini
about 1690.
Structure: pressure to make
hydrogen into a liquid.
May have rocky core.
23.3 Outer Planets (and Pluto)
Jupiter:
Moons:
Io- volcanic
Eurpoa- fractured icy surface
Ganymede- largest, parallel
groves
Callisto- many craters
23.3 Outer Planets (and Pluto)
Jupiter:
Rings:
Very faint
Maybe fragments
of 2 smaller
moons
23.3 Outer Planets (and Pluto)
Saturn:
Rings: Main feature
100 m thick
23.3 Outer Planets (and Pluto)
Saturn:
Moons:
56 currently
Titan – largest
Atmosphere and
hydrocarbon seas
Enceladus-volcanic
and water geysers
23.3 Outer Planets (and Pluto)
Uranus: Planet on its
side.
Winking star was a
sign of a ring (9)
Miranda
23.3 Outer Planets (and Pluto)
Neptune: Windy Planet
1000km/hr
Great Dark Spot: Storm
like Giant red Spot.
Vanished! Repapered.
Methane clouds.
Triton –retrograde and
volcanic
23.3 Outer Planets (and Pluto)
Pluto: Dwarf Planet
Fails to attract object
in its orbit. (clearing
its orbit)
228 years
Charon-moon
23.4 Minor Members
NEAR Shoemaker
Landed on asteroid
Eros
Very low gravity
Most asteroids are
between Mars and
Jupiter.
23.4 Minor Members
Comets
Made of rocks, frozen
water, methane,
carbon dioxide and
carbon monoxide.
Very elongated orbits.
Tail points away from
the sun.
23.4 Minor Members
Comets
Many short period
come from the
Kuiper Belt
Long period come
from the Oort
Cloud
23.4 Minor Members
Comets
Halley’s Comet
1986 Giotto probe
passed within 600
km
8 km x 16 km
23.4 Minor Members
Meteoroids
Small solid particles
3 sources:
interplanetary debris
asteroid belt
comet remains
Meteors-burn up in contact
with atmosphere.
Meteorites- reaches Earth
23.4 Minor Members
Meteoroids
Age of meteorites are
about 4.567 billion
years old.
Made mostly of iron.
Meteor Showersannual event from
comet passes across
Earth’s orbit.