Download CHAPTER 23 – SOLAR SYSTEM

CHAPTER 23 –
SOLAR SYSTEM
23.1
• Our solar system contains the sun,
8 planets, 3 dwarf planets, moons,
asteroids, comets, and meteors
– Sun takes up 99.85% of mass in solar
system
– Order of planets: Mercury, Venus,
Earth, Mars, Jupiter, Saturn, Uranus,
and Neptune
– All planets move in ellipses around
the sun & all travel in the same
direction
• Formed via the Nebular Hypothesis –
the sun & planets formed out of a
rotating cloud of gas (H & He) & dust
called a nebula
• Nebula began to spin = gravity
• Began to spin faster & contracted to
form planetesimals (small, irregular
shaped solid bodies) that grew larger
over time to form planets
2 TYPES OF PLANETS
1. TERRESTRIAL
•Mercury, Venus, Earth,
Mars
2. JOVIAN
•Jupiter, Saturn, Uranus,
Neptune
• TERRESTRIAL PLANETS ARE:
–Relatively small size
–Rocky & metallic substances in core,
little ice or gas
–Thin atmosphere (because of smaller
mass)
–Located close to sun
–Inner planets)
–High Densities
• JOVIAN PLANETS ARE:
–Large size
–Composed primarily of gas (H & He) & ice
(NH3, CH4, & CO2)
–Small iron (Fe) cores
–Thick atmosphere of H, He, methane (CH4)
& ammonia (NH3)
–Located far from sun
–Outer planets)
–Small Densities
• Gas Giants
• Pluto doesn’t fit into either category
OTHER OBJECTS IN THE SOLAR SYSTEM
• Comets – pieces of rocky & metallic
materials held together by frozen gases like
water vapor, methane, carbon dioxide, &
carbon monoxide
– Travel in elongated orbits that take up to
thousands of years to complete
– Glowing head = Coma
– Tail forms behind as solar energy vaporizes
the frozen gases (probably caused by solar
wind)
• Tail always points away from the sun
–Haley’s Comet – orbits Earth every
76 years (next time is 2062)
–Comets eventually break apart
–Originate in:
• Kuiper Belt = region just beyond
Neptune
• Oort Cloud = outer edge of solar
system
ASTEROIDS
–Asteroids – small rocky
bodies
–Irregular shapes
–Most asteroids lie between
Mars & Jupiter in an Asteroid
Belt
METEOROID – small solid particle
that travels through space
– Shooting stars, light is caused by friction
between particle & the atmosphere
– Originate by:
• Interplanetary debris that was not
accumulated into a planet when the solar
system was forming
• Material from asteroid belt
• Solid remains of comets
– Most are the size of sand grains & vaporize
within Earth’s atmosphere = Meteors
• METEOR SHOWERS – when meteor
sightings reach 60 or more per hour,
result when Earth encounters a swarm
of meteoroids traveling in the same
direction as Earth
–Perseid Shower occurs each year
around August 12th
–A meteoroid that reaches Earth’s
surface without burning up is called a
Meteorite
–Create large impact craters
23.2
1. MERCURY
– Innermost planet
– Smallest planet (little larger than the Moon)
– Surface is covered by cratered highlands (similar
to the Moon)
– Very dense – large iron core for its size
– Quick revolution time (1 mercury year = 88 earth
– slow rotation time (1 mercury day = 179 earth
days)
• Nighttime temps = -173°C
• Noontime temps = 427°C
– Greatest temperature extremes of any planet
2. VENUS
– Second brightest object in Earth’s night sky (only the
Moon is brighter)
– Revolves in nearly a perfect circle (1 Venus year = 255
Earth days)
– Similar in size, density, mass, & location to Earth = called
“Earth’s Twin”
– Thick atmosphere made of 97% Carbon Dioxide
• Surface pressure is 90X’s more than Earth’s because
of thick atmosphere
• Creates a “Run-Away Greenhouse Effect” by trapping
heat at surface
• Surface temperature = 475°C (Venus is hottest planet)
– Surface features are plateaus, mountains, & huge
volcanoes that covered the surface with basaltic lava
that were determined by radar mapping
4. MARS
• Easily visible with telescope
• Known as the Red Planet because of rusty
colored dust on surface
• Thin atmosphere (1% as dense as Earth’s)
made of Carbon Dioxide
• Polar ice caps made of ice (H2O) & frozen
carbon dioxide
• Temps range from -70°C to 100°C
• Extensive dust storms because of strong
winds (270 km/hr)
MARS CON’T.
• Large shield volcanoes – Olympus Mons
(Largest volcano in solar system @23 km high)
• Large canyons – Valles Marineris (Many kms.
Longer than Grand Canyon), created by large
faults
• Possible water drainage patterns on surface
similar to those on Earth
• Currently being explored by rovers Spirit &
Opportunity
• 2 moons – Phobos & Deimos (captured
asteroids), very small in size
OUTER
PLANETS
5. JUPITER
• By far the largest planet (2.5 times the mass
of all other planets combined)
• Fastest rotation (1 Jupiter day = 10 Earth
hours)
• Appears to have alternating bands of
multicolored clouds = very fast wind belts
caused by high release of internal heat
• Great Red Spot = giant hurricane-like storm in
southern hemisphere
• Atmosphere is made of H & He
JUPITER CON’T.
• Liquid surface (because of intense pressure) made of H
• Core is liquid metallic H
• Ring system made of fine dust particles
• 63 moons (4 are Galilean Moons):
– Io = volcanically active due to the tidal energy generated
by the constant tug of war between Jupiter & the other
Galilean moons
– Europa = smallest, icy surface (possible water beneath),
will be explored for life
– Ganymede = largest moon in the solar system; smooth &
cratered surface
– Callisto = outermost, densely cratered
6. SATURN
• 1 Saturn revolution = 29.46 Earth years
• Similar in atmosphere, composition, & internal
structure to Jupiter
• 2nd largest planet
• Extensive ring system first discovered by Galileo
– Consist of multiple concentric rings composed of
ice & rock with gaps in between
– Main Rings (A & B) are tightly packed & dense,
very bright/visible
– Thin outer rings are widely spaced
• SATURN CON’T.
• Very fast wind speed in atmosphere =
up to 1,500 km/hr
• Alternating bands of storms in
atmosphere
• 31 moons
–Titan is 2nd largest moon in solar
system & is larger than Mercury,
has substantial atmosphere
7. URANUS
–Unique rotation = axis of planet is at
90°, so Uranus appears to rotate on its
side
• Thought to be caused by a giant
impact that forced the planet to roll
over
–Faint ring system made of 9 distinct ring
belts
–25 moons
• Miranda = Large size & varied
landscape
8. NEPTUNE
• Very active atmosphere – constant winds
at 1,000 km/hr=windiest place in solar
system
• Atmosphere made of mostly nitrogen
• Large storm systems = Great Dark Spot
• Cirrus-like clouds occupy atmosphere,
thought to be made of frozen methane
(gives planet a bright blue color)
• NEPTUNE CON’T.
• Lowest surface temperature measured yet at
-200°C
• Faint ring system
• 13 known moons
–Triton = largest moon of Neptune, exhibits
retrograde motion (rotates opposite of
Neptune) – captured asteroid
–Also displays volcanic activity
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PLUTO
No longer the smallest planet, now called Dwarf planet
Located within a swarm of other icy objects
40 times farther from the sun than Earth
Slow orbital speeds, 1 year on Pluto = 248 Earth years
Highly eccentric (angled orbit) – occasionally Pluto is closer
to te sun than Neptune
• Icy world = “dirty snowball”
– Temperature is estimated at -210°C
• 1 moon = Charon, very similar in size to Pluto
– Orbits very close to Pluto (20X’s closer than our Moon)
• QUALIFICATIONS FOR DWARF PLANET
• Must be in orbit around the Sun
• Has sufficient mass for its self-gravity to
overcome rigid body forces so that it can
assume a hydrostatic equilibrium shape
(near-spherical)
• Has failed to clear the neighborhood
around its orbit
• Is not a satellite
• DIFFERENCE BETWEEN DWARF PLANET & PLANET
– The only difference between a dwarf planet & planet is
that a planet has cleared its neighborhood around its
orbit
• 3 DWARF PLANETS IN OUR SOLAR SYSTEM
– Ceres
• Located in the Asteroid belt between Mars & Jupiter
– Pluto
• Located in Kuiper belt
– Eris (UB313)
• Located in Kuiper belt