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The Solar System
PSCI 131: The Solar System
Terms
• Ecliptic
– Imaginary plane within which the 8 major
planets orbit the Sun
– Apparent path of Sun across the sky as seen
from Earth
PSCI 131: The Solar System
Terms: Ecliptic
From: Wikipedia.org
PSCI 131: The Solar System
The Solar System
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The Early Solar System
Overview
The Terrestrial Planets
The Jovian Planets
Dwarf Planets
Asteroids
Comets
Meteoroids
The Early Solar System
PSCI 131: The Solar System – The Early Solar System
The Early Solar System
The Nebular Theory
From: jcconwell.wordpress.com
PSCI 131: The Solar System – The Early Solar System
The Early Solar System
The Nebular Theory
Planets formed
from collisions of
smaller objects
Solar System Overview
PSCI 131: The Solar System – Overview
Overview of the Solar System
• Sun: >99% of solar system’s mass
• Major planets
– 4 terrestrial
– 4 Jovian
• Dwarf planets
– At least 5 recognized so far by IAU
PSCI 131: The Solar System – Overview
Overview of the Solar System
• Asteroids, comets, meteoroids
– Leftover material from solar system formation
– Fragments from collisions
• Dust, gas, radiation
The 8 Major Planets
PSCI 131: The Solar System
What Is A Major Planet?
• Spherical
• Orbits Sun
• Not a moon
• Has cleared its orbital path of other objects
PSCI 131: The Solar System – The 8 Major Planets
Major Planets and Sun
The major planets, shown to scale
PSCI 131: The Solar System – Terrestrial Planets
The Four Terrestrial Planets
• “Terrestrial”: Earth-like
• Mercury, Venus, Earth, Mars
The terrestrial planets, shown to scale
From: wikipedia.org
PSCI 131: The Solar System – Terrestrial Planets
The Four Terrestrial Planets
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Small
Rocky
Dense
Thin atmospheres
Short years
Long days
Main heat source: Sun
EARTH
MARS
VENUS
MERCURY
From:
wikipedia.org
PSCI 131: The Solar System – Terrestrial Planets
Mercury
• Orbital period: 88 days
• Rotation period: 59 days
• Temp range: -270° F – 870° F
• Atmosphere: None
From: wwu.edu
From: wikipedia.org
From: wikipedia.org
PSCI 131: The Solar System – Terrestrial Planets
Venus
• Orbital period: 225 days
Cloud cover of Venus.
• Rotation period: 243 days
From: ircamera.as.arizona.edu
• Temperature: 900° F
• Atmosphere: 97% CO2
Surface of Venus, photographed with cloud-penetrating radar.
From: annesastronomynews.com
PSCI 131: The Solar System – Terrestrial Planets
Earth
• Orbital period: 365.25 days
• Rotation period: 23 hr 56 min
• Temperature: 58° F (2012
average)
Earth as seen from the Moon.
From: science1.nasa.gov
• Atmosphere: Nitrogen, oxygen,
argon, water, CO2
Earth from low-altitude orbit.
From: astexhibits.com
PSCI 131: The Solar System – Terrestrial Planets
Mars
• Orbital period: 687 days
• Rotation period: 24 hr 37 min
• Temperature: -80° F (average)
• Atmosphere: Thin, CO2
Mars from low-altitude orbit,
showing atmosphere.
From: wikipedia.org
PSCI 131: The Solar System – Terrestrial Planets
Mars
Olympus Mons volcano
Volcanoes and water ice clouds on Mars. Olympus Mons. Cliff at base is 5 miles
From: jpl.nasa.gov
high. Inset shows height compared to
Earth mountains.
From: wikipedia.org
PSCI 131: The Solar System – Jovian Planets
The Four Jovian Planets
• “Jovian”: Jupiter-like
• Jupiter, Saturn, Uranus, Neptune
The Jovian planets, shown to scale
From: cseligman.com
PSCI 131: The Solar System – Jovian Planets
The Four Jovian Planets
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Gas & ice
Low density
Long years
Jovian planets compared to the Sun and Earth (far
Short days
right) Modified from: wikipedia.org
Main heat source: internal (from gravitational
compression)
PSCI 131: The Solar System – Jovian Planets
Jupiter
• Orbital period: 12 years
• Rotation period: 9 hr 56 min
• Temperature: -234° F (cloud tops)
• Atmosphere: Hydrogen, helium
From: photojournal.jpl.nasa.gov
Jupiter as it would look if it were
the same distance from Earth
as the Moon.
From: tholtz.com
PSCI 131: The Solar System – Jovian Planets
Jupiter: The Great Red Spot
High-res photo of the Great Red Spot, an ancient storm the size of three Earths.
PSCI 131: The Solar System – Jovian Planets
Saturn
• Orbital period: 30 years
• Rotation period: 10 hr 30 min
• Temperature: -288° F (cloud tops)
Saturn imaged by the Cassini-Huygens
spacecraft, 2008. From: nasa.gov
• Atmosphere: Hydrogen, helium
Earth as seen from Saturn
Saturn’s rings and Earth, taken by Cassini-Huygens
spacecraft, 2008. From: nasa.gov
PSCI 131: The Solar System – Jovian Planets
Saturn’s Moon Titan
Comparison of Titan with Earth and Earth’s
moon.
• Atmosphere: Nitrogen, methane
•Only moon known to have an
atmosphere
• Bodies of stable liquid on surface
•Methane, ethane
Titan’s surface.
From: nasa.gov
PSCI 131: The Solar System – Jovian Planets
Uranus
• Orbital period: 84 years
• Rotation period: 17 hr 14 min
• Temperature: -357° F (cloud tops)
• Atmosphere: Hydrogen, helium,
frozen ammonia and methane
Axis
Uranus showing rings and cloud
bands.
From: nasa.gov
•Rotates on its side:
PSCI 131: The Solar System – Jovian Planets
Neptune
• Orbital period: 165 years
• Rotation period: 16 hr 7 min
• Temperature: -392° F (cloud tops)
• Atmosphere: Hydrogen, helium,
frozen ammonia and methane
Neptune with cloud bands, cirrus clouds (white) and
storm systems (dark spots). From: nasa.gov
PSCI 131: The Solar System
The Dwarf Planets
PSCI 131: The Solar System
What Is A Dwarf Planet?
• Spherical
• Orbits Sun
• Not a moon
• Has NOT cleared its orbital path of other objects
PSCI 131: The Solar System – Dwarf Planets
Five Recognized Dwarf Planets
(Listed in order of decreasing size)
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Eris
Pluto
Makemake
Haumea
Ceres
• All are located in “debris belts”
Debris Belt Locations
Orbit of Earth
Orbit of Mars
ASTEROID
BELT
SUN
Orbit of Uranus
Orbit of Neptune
KUIPER
BELT
Debris Belt Locations
Orbit of Uranus
OORT
CLOUD
KUIPER
Orbit of Neptune
BELT
ASTEROID BELT
PSCI 131: The Solar System – Dwarf Planets
Five Recognized Dwarf Planets
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Eris: Kuiper Belt
Pluto: Kuiper Belt
Makemake: Kuiper Belt
Haumea: Kuiper Belt
Ceres: Asteroid Belt
• Oort Cloud: No recognized dwarf planets; trillions of
comets
Dwarf Planet Pluto
• Visited by New
Horizons probe
July 2015
• Probe launched in
2006-nine year
trip
Dwarf Planet Pluto
Ice mountains
Ice plains
PSCI 131: The Solar System
The Smaller Objects:
Asteroids, Comets, &
Meteoroids
PSCI 131: The Solar System – Smaller Objects
Asteroids
• Size: 10s to 100s of miles
• Shape: Irregular
• Composition: Rock, metal
• Atmosphere: None
• Location: Mostly in Asteroid Belt
between Mars and Jupiter
PSCI 131: The Solar System – Smaller Objects
The Asteroid Belt…
…doesn’t look like this.
PSCI 131: The Solar System – Smaller Objects
What Does the Asteroid Belt Look Like?
It’s mostly empty space
PSCI 131: The Solar System – Smaller Objects
Asteroids: Earth Crossers
PSCI 131: The Solar System – Smaller Objects
Comets
• Size: average diameter about 5 miles
• Shape: Irregular
• Composition: Ice, rock & metal
fragments
• Atmosphere: None
• Location: Kuiper Belt & Oort Cloud
Halley’s Comet, 1986
From: dailygalaxy.com
PSCI 131: The Solar System – Smaller Objects
Comets
Structure of a comet
PSCI 131: The Solar System – Smaller Objects
Comets
A comet’s coma and tail only form near the
Sun. The tail always points away from the Sun.
PSCI 131: The Solar System – Smaller Objects
Comets
Comet Shoemaker-Levy struck Jupiter in 1994.
PSCI 131: The Solar System – Smaller Objects
Meteors
• Size: sand grain
(average)
• Composition:
Rock, metal
PSCI 131: The Solar System – Smaller Objects
Meteors
• Meteor: within a planet’s atmosphere
• Meteorite: has struck the ground
• Meteoroid: still in space
PSCI 131: The Solar System – Smaller Objects
The Chelyabinsk “Meteor”, February 15, 2013
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Approx. mass: 11K tons
Approx. size: 60 ft
Velocity: 41K mph
Altitude of airburst: 76K feet
Energy: 500K tons of TNT
Injuries: 1,491
Damage: 7,200 buildings
VIDEO: Chelyabinsk meteor airburst and building damage
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