Download Ch 16 Handout

5/6/14 Ch 16.1-­‐6: The Solar System Hmwk: M: a-­‐I, k-­‐q, s, t, w & x; MC: 1, 5-­‐15; SA: 2, 3, 5-­‐20. •  Astronomy – the scientific study of the universe
beyond Earth’s atmosphere
•  Universe – everything, all energy, matter, and
space
•  The Milky Way– one of 50 billion galaxies
scattered throughout the universe
•  Solar System – complex system of moving
masses around Sun held together by
gravitational forces
•  8 major planets, over 170 moons, 4 dwarf
planets, and 1000’s of other objects (asteroids,
comets, meteoroids, etc.)
•  Sun – supplies the energy for nearly all life on
the planet earth
1 5/6/14 Astronomers use EM radia;on to study Universe Planetary Mo;on Planet: Greek for wanderer
Geocentric Model – everything revolved around
Earth (Ptolemy, AD 140)
Heliocentric Model – Sun-centered model
(Copernicus: 1473-1543)
Kepler’s 1st Law – Law of Elliptical Orbits
Astronomical Unit (AU): average distance b/t
Earth and Sun (1.5 x 108 km; 9.3 x 107 mi) 2 5/6/14 Major Planet Classifica;ons •  Sun – 99.87% mass of solar system
•  Of remaining 0.13%, Jupiter is > 50%
Terrestrial (inner) Planets:
•  Mercury, Venus, Earth & Mars
•  High % of more massive (non-gaseous) elements (most
H and He gone)
•  Small size, rocky & metal composition, no rings
Jovian (outer) Planets:
•  Jupiter, Saturn, Uranus, & Neptune
•  High % of less massive gaseous elements (most H and
He remains)
•  Rocky core composed of iron and silicates
•  Thick layers of frozen methane, ammonia, and water
above core
3 5/6/14 Revolu;on vs. Rota;on Revolve around Sun versus rotate on axis Counterclockwise: direct/prograde moKon Clockwise rotaKon: retrograde (Venus and Uranus) sSize Comparison 4 5/6/14 Conjunc;on & Opposi;on and conjuncKon with Mars Earth Facts •  Solid, spherical, rocky body w/ oceans &
atmosphere (21% O2)
•  Large amounts of surface H2O: s, liq. & gas
•  Unique: temperate climate, O2 -containing
atmosphere, and living organisms
•  Oxidized environment: > 90%, by volume, of the
rocks/minerals in Earth’s crust contain oxygen
–  Quartz – SiO2, Calcite – CaCO3, Feldspar –
KAlSi3O8
•  Oblate spheriod: bulges at equator- rotation
•  Pole Diameter ~ 43 km < Equatorial Diameter
–  Small fraction since ave. dia. = 12,900 km
5 5/6/14 Albedo: fraction of sunlight reflected by object
•  Earth: 33% (clouds, ice & water)
•  Moon: 7% (brightest object in night sky)
•  Venus: 76% (2nd brightest in sky)
Earth’s Movement: Rota;on and Revolu;on Difficult to Prove RotaKon: Jean Foucault in 1851 (Foucault’s
Pendulum)
6 5/6/14 Revolution about Sun
Parallax– apparent
motion, or shift, that
occurs b/t two fixed
objects when observer
changes position
•  Nearby stars appear
to shift w/ respect to
distant stars
•  Used to determine
distance to nearby
stars 7 5/6/14 Mercury: named aJer the swiJ messenger of the Roman gods Shortest period of revolution: 88 days
3 rotations for every 2 revolutions
Temperature range:
+473oC to -173oC
Practically no atmosphere
Density close to Earth’s
Venus: Roman god of beauty Closest planet to Earth
Surface not visible from Earth
Thick CO2 clouds; Atmos: 96% CO2
90 atm; +477 °C
Most surface rocks volcanic
Few impact craters
8 5/6/14 Mars: Roman God of War Two outstanding features:
polar ice caps and extinct
volcanoes
Ice caps: frozen CO2 (winter);
CO2(g) & H2O(s) (summer)
Largest known volcano in
solar system: 24 km high; ~3
X as big as Mauna Loa
Red color: fine grain iron
oxide minerals?
Jupiter: Roman Supreme God Largest planet: vol. & mass; Dia.: 11 X Earth’s
318 X more massive than Earth
Average density: ~1.3 g/cm3
Covered w/ thin layer of clouds composed of H,
He, methane, ammonia, and several others
Great Red Spot:
erratic movement,
shape, color, and
size – sometimes
even disappearing
Likely a huge counterclockwise
“hurricane-like” storm, lasting
hundreds of years
~10 hour days
9 5/6/14 Saturn: Roman God of Agriculture Saturn Three prominent rings, seven distinct rings
Most of any Jovian planet
Rings inclined 27o to orbital plane
Rings thought to be composed of ice and icecoated rocks (micrometers à 10 m)
Most spectacular sight that can be viewed from
Earth with a small telescope
Diameter is 9 times Earth’s -- 95 times more
mass than Earth
Average density of only 0.7 g/cm3
10 5/6/14 Uranus: named aJer father of Titans and grandfather of Jupiter Thin ring system composed of boulder-size particles (>1m)
Average density: only 1.3 g/cm3
Revolves around Sun on its side
Rotates in a retrograde fashion
Neptune: Roman God of the Sea Existence predicted due to Uranus’
motion
Large dark spot similar to Jupiter:
thought to be due to large wind systems
Neptune and Uranus are similar in
size and in the composition of their
atmospheres
Two planets often considered twins
11 5/6/14 Designations of Celestial Bodies
International Astronomical Union (IAU) In 2006 the IAU adopted the following criteria for a solar
system body to be a planet:
(1)  It must be in orbit about the Sun.
(2) It must have sufficient mass for self-gravity to
form a nearly round shape.
(3) It must be the dominant body within its orbit.
Pluto’s orbit goes inside of Neptune’s orbit- not planet
Two new categories:
1)  Dwarf planets: Pluto, Ceres and Eris
2)  Small solar-system bodies: Kuiper Belt (beyond
Neptune & into Ceres orbit) and asteroid belts
12 5/6/14 Ceres (goddess of agriculture): 1st Dwarf Planet from Sun
•  Lies in asteroid belt between Mars and Jupiter
•  Diameter of 940 km- smallest dwarf planet
Pluto (god of outer darkness): 2nd Dwarf Planet from Sun
•  Average density: 1.65 g/cm3
•  Does not resemble either terrestrial or Jovian Planets
Eris (goddess of chaos & strife): 3rd Dwarf Planet from Sun
•  Previously known as 2003 UB313 (or Xena)
•  Slightly larger & ~3 X farther away from Sun than Pluto
•  Highly elliptical orbit- takes 560 Earth yrs for one
revolution
Haumea mass 30% of Pluto and orbits at 43 AU
Makemake mass 75% of Pluto and orbits at 75 AU
Edge of Universe: ~100 AU
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