The solar system consists of the Sun, the planets including our Earth, their satellites, plus many s

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THE SOLAR SYSTEM

• The solar system consists of the Sun, the planets
  (including our Earth), their satellites, plus
  many smaller objects, including asteroids and
  comets.
• The entire solar system, including the Sun and
  Earth, is believed to have been created about 4.6
  billion years ago.
• The size of the solar system is not well defined
  however, one could (until recently) state it as
  being at least as large as the orbit of the
  planet Pluto, which can be as much as 40 times
  Earths distance from the Sun.
• Recently, detections of other objects comparable
  to and larger than Pluto, at even larger
  distances (in the zone known as the Kuiper Belt),
  have greatly extended the known size of the solar
  system.
• One could also define the size of the solar
  system to include the entire zone in which the
  solar wind (gas outflowing from the Sun)
  dominates over the gas constituting the
  interstellar medium (as determined most recently
  by the Voyager 1 spacecraft) to about 95 times
  the diameter of Earths orbit around the Sun.
• However, the size of the solar system is quite
  small compared to the distance to the closest
  star other than our Sun, which is about 9000
  times Neptunes distance from the Sun.

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THE SUN

• The Sun is the central object of the Solar
  System, around which all the planets and other
  objects revolve.
• The Sun is 109 times Earths diameter (and 10
  times the diameter of Jupiter, the largest
  planet), and has more than 300,000 times Earths
  mass.
• The Sun is composed of 90 hydrogen and 10
  helium (by number of atoms), with less than 1 of
  all heavier elements.
• The composition of the Sun is similar to those of
  other stars, and of the interstellar medium.
• The Sun derives its energy by thermonuclear
  fusion, in which four atoms of hydrogen are
  combined to make one atom of helium.
• The Sun and solar system are about 4.6 billion
  years old, but the total lifetime of the Sun
  (before depleting its supply of hydrogen fuel) is
  about 10 billion years.

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The Sun
Jupiter to Scale
Jupiter to Scale
Earth to Scale
Earth to Scale
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THE INNER SOLAR SYSTEM
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MERCURY

• Mercury is the planet closest to the Sun, has a
  highly eccentric orbit, and rotates on its axis 3
  times for each 2 orbits around the Sun.
• Mercury has no significant atmosphere, and like
  the Moon, is heavily cratered by meteoroid
  impacts.
• Mercury is about 1/3 Earths diameter, has a
  larger iron core (relative to its size) than
  Earth, and has a weak magnetic field.
• Close-up images of Mercury were obtained in the
  Mariner 10 fly-by space mission in 1974-1975.
• Currently, a new space mission, Messenger, was
  launched August 2, 2004, and is due to arrive at
  Mercury March 18, 2011.

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Mariner 10 Images of Mercury
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Mariner 10 Close-Up View of Mercury (Caloris
Basin)
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Mercurys Southern Hemisphere
Mercurys South Pole
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MESSENGER MISSION TO MERCURY

• The Messenger mission to Mercury, the first since
  the Mariner 10 mission, was launched August 2,
  2004 and is due to arrive at Mercury March 18,
  2011.
• Messengers mission will include two flybys of
  Venus and three flybys of Mercury, before it
  enters orbit around Mercury in 2011.
• The primary mission, in orbit around Mercury, is
  planned to last for one year.
• Scientific objectives include finding answers to
  the following questions
• Why is Mercury so dense?
• What is the geologic history of Mercury?
• What is the structure of Mercurys core?
• What is the nature of Mercurys magnetic field?
• What are the unusual materials at Mercurys
  poles?
• What volatiles are important at Mercury?

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VENUS

• Venus, the second planet outward from the Sun, is
  nearly the same size and mass as Earth.
• The atmosphere of Venus is quite different from
  that of Earth it consists mostly of carbon
  dioxide with a surface pressure 90 times Earths
  sea-level atmospheric pressure, and has a surface
  temperature of about 750 K ( 480o C or 900o F).
• Nitrogen constitutes about 3 of the atmosphere
  of Venus, or nearly 3 times the amount in Earths
  atmosphere.
• There is very little water vapor or free oxygen
  in the atmosphere of Venus.
• The lack of water is thought to be one reason for
  the predominance of CO2 in the atmosphere of
  Venus.
• The surface of Venus is completely obscured, in
  visible light, by a dense cloud layer containing
  droplets of sulfuric acid (H2SO4).
• Russian lander spacecraft have imaged and
  otherwise studied the surface environment of
  Venus at two locations.
• The surface of Venus has been mapped, using radar
  imaging, by the Magellan spacecraft. Both
  volcanic and asteroid-impact features are present.

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TWO VIEWS OF VENUS
Near UV (Pioneer Venus)
Radar (Magellan)
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Soviet Venera Lander Images of the Surface of
Venus

• These are, to date, the only visible-light
  images obtained from the surface of Venus (at two
  separate locations, by two landers).
• Both landers were only able to operate for a
  short period of time before being disabled by the
  extreme heat of the surface environment.

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Magellan Radar Images of the Surface of Venus
Asteroid Impact Crater
Pancake-like Volcanic Lava Domes
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Magellan False-Color Radar Maps of the Surface of
Venus
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EARTH AND MOON

• Our home planet, Earth, is unique in many
  respects, but is also average among the planets
  of our solar system in other respects.
• Earth, as the largest of the four inner planets,
  is about average in size and mass in the solar
  system (four planets are smaller, and four are
  larger).
• Earth is the only planet in the solar system with
  an atmosphere containing a significant proportion
  of molecular oxygen.
• Earth is also the only planet having liquid water
  on its surface.
• As far as we know, Earth is the only planet
  having living organisms.
• With the exception of Pluto, Earth has the
  largest satellite (our Moon) relative to the size
  of its primary.
• Our Moon is actually somewhat larger than Pluto
  (as are some satellites of Jupiter and Saturn),
  which has led some to consider Pluto not to be a
  major planet.

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MARS

• Mars, the fourth planet from the Sun, is about
  half Earths diameter and 0.1 times Earths mass.
• The atmosphere of Mars has less than 1 of
  Earths surface pressure, and consists mostly of
  carbon dioxide.
• Mars has a colder climate than Earth the day to
  night temperature range at its equator is about
  the same as the summer to winter temperature
  range at Earths south pole.
• During winters in the north or south polar
  regions, CO2 can freeze to form dry ice.
• In contrast to Venus, there is evidence of water
  on Mars, in the form of water ice (polar caps),
  as hydrated surface minerals, and probably as
  underground permafrost.
• Dry riverbeds on Mars indicate that in the
  distant past, Mars had a much denser atmosphere
  and a warmer climate than it has at present.
• Mars has been studied by several spacecraft
  missions, including orbiters and landers, and is
  the target of several new missions.

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Mars Opposition, October 2005Observed by Hubble
Space Telescope
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Composition of the Lower Atmosphere of Marsfrom
Viking Lander Measurements
Gas Carbon Dioxide (CO2) Nitrogen (N2) Argon
(Ar) Oxygen (O2) Carbon Monoxide (CO) Water
Vapor (H2O) Neon (Ne) Krypton (Kr) Xenon
(Xe) Ozone (O3)
Proportion 95.32 2.7 1.6 0.13
0.07 0.03 2.5 ppm 0.3 ppm 0.08
ppm 0.03 ppm
Discovered by Viking lander experiments Variabl
e
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Viking Orbiter Views of Mars
Dry River Beds?
Extinct Volcano- Olympus Mons
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Viking Lander Views of Mars Surface
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Mars Pathfinder Views of Mars Surface
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Mars Global Surveyor Images of Mars
Valles Marineris Detail
Evidence for Recent Liquid Water
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South Polar Cap as Viewed by Mars Global Surveyor
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Mars Odyssey Infrared Image of Mars Southern
Hemisphere
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Mars Odyssey Map of Epithermal Neutron Emission
from Mars Near-Surface Regions
Blue areas are zones indicating sub-surface water
ice (permafrost).
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2003 Mars Exploration Rover (with Mars
Pathfinder Sojourner rover, for scale, at right)
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Mars Exploration Rover in Action (Artists
Concept)
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Map of Mars Opportunity Rover Landing Site Region
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View of the Martian Surface (Gusev Crater) from
Mars Rover Spirit
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View of Mars Surface from Rover Opportunity,
showing Rock Outcrops
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View of Mars Bounce Rock from Opportunity
Rover, and Rock Abrasion Tool Studies
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Closeup Microscope Views of Mars Rock Robert E
by Opportunity Rover
Layered texture and blueberries indicate the
rock formation was deposited in liquid water in
the distant past (sedimentary rock).
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Mars Rovers Explore Their Surroundings
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Mars Rover Spirit Panorama of Columbia Hills and
Gusev Crater
Mars Rover Opportunity Panorama of Olympia
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Mars Reconnaisance Orbiter

• The Mars Reconnaisance Orbiter (MRO) is the most
  recent, and most technically advanced, Mars space
  mission launched by the United States.
• MRO was launched in August, 2005 and is planned
  to go into orbit around Mars in March, 2006.
• MRO science objectives include studies of the
  distribution of water on Mars, in the forms of
  ice, liquid, and in combination with rocks and
  minerals.
• MRO will observe the entire surface of Mars, with
  higher resolution than any previous Mars-orbiting
  missions.