1. Touring Our Solar System
Good link:
Chapter 23
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3. The Solar System Ch. 23.1 What are the 2 “planetary neighborhoods”?
inner planets
outer planets
What separates these 2 “neighborhoods?”
asteroid belt

4. The Solar System What are the inner planets? 4 closest to sun
Mercury
Venus
Earth
Mars
What is another name for the inner planets?
“terrestrial” planets
b/c earth-like characteristics
rocky crusts
dense mantle layers
very dense cores
Distance Between Planets Visualization

5. The Solar System What are asteroids? Where are asteroids located?
solid, rocklike masses that orbit the sun in same direction as planets
Where are asteroids located?
between Mars & Jupiter in asteroid belt that separates inner planets from outer planets

6. The Solar System What are the outer planets?
remaining 4 planets
Jupiter
Saturn
Uranus
Neptune
What is another name for the outer planets?
“Jovian” planets or Gas Giants
How do they compare to the terrestrial planets?
considerably larger than Earth
gaseous
less dense
have ring systems
Composed mainly of light elements  Hydrogen (H) & Helium (He)
3 common properties of ring systems:
Consist of many particles in independent orbits around planet
Closer to the planet than the major moons
Orbit over the planet’s equator

7. The Solar System What about Pluto??? oddity of the solar system
Not dense enough to be considered “terrestrial”.
Too small to be “Jovian”.

8. The Terrestrial (Inner) Planets sec. 23.2 Fun Facts
Mercury
surface
many craters
No atmosphere (due to weak gravity)…
So… no weather to erode craters
smooth plains
formed by lava flowing from cracks in surface
extremely hot day temps (400+°C) & extremely cold night temps (-200°C)
due to lack of atmosphere
MESSENGER Orbits Mercury (AMNH Sci Bulletin)

9. Terrestrial (Inner) Planets: Fun Facts
Venus
“Earth’s twin/sister planet”
similar diameter, mass, gravity
Unlike other planets rotates east to west (clockwise)
atmosphere = mostly carbon dioxide (CO2)
“runaway” greenhouse effect (~475°C)
yellow clouds = sulfuric acid
All other planets rotate counterclockwise/west to east (if looking from top down)

10. Terrestrial (Inner) Planets: Fun Facts
Mars
Axis tilted at almost same angle & in same direction as Earth’s
similar 4 seasons but ~2x as long (since year is ~2x longer than Earth’s)
largest volcano in the solar system = Olympus Mons
Valles Marineris canyon system (as long as U. S. is wide)
Curiosity: Searching for Carbon (AMNH Sci Bulletin)

11. The Outer Planets: Fun Facts Ch. 23.3
Jupiter
More than 2x mass of all other planets combined
Colored zones & belts
“Great Red Spot”
May be calm area that rotates slowly in turbulent atmosphere

12. The Outer Planets: Fun Facts Ch. 23.3
Saturn
less dense than water (1g/cm3)
would float
most visible ring system
believed to be chunks of ice
colored zones & belts
rising & sinking gases
fewer than Jupiter
How Did Saturn Get Its Rings? (AMNH Sci Bulletin)
Saturn System Is Showing Its Age (AMNH Sci Bulletin)

13. The Outer Planets: Fun Facts Ch. 23.3
Uranus
inclination (tilt) of axis almost 90°
So… rotates on its side
may have been tipped by collision early in history of solar system
blue tint from methane

14. The Outer Planets: Fun Facts Ch. 23.3
Neptune
occasionally outside Pluto’s orbit
b/c Pluto’s orbit sometimes brings Pluto closer to the sun than Neptune
Astronomers predicted existence mathematically
in 1846

15. The Outer Planets: Fun Facts Ch. 23.3
Pluto
No longer “true” planet
Now one of 40+ “dwarf” planets
Not dense enough to be “terrestrial” & too small to be “Jovian”.
Smaller than 7 moons in our solar system (including our moon)
New Horizons probe to Pluto launched Jan. 2006
will fly by Pluto & Charon ~2015
Occasionally the 8th “planet” b/c Pluto’s orbit sometimes brings it closer to the sun than Neptune
Every 248 years… For ~20 years… Switched to 8th “planet” in 1979 & then switched back to 9th “planet” on 2/11/1999
Thought to be larger than it is until 1978 when astronomers discovered that it had a moon about ½ its size
Moon  Charon (Diameter ~ 1200 km)
Since Pluto & Charon are similar in mass, some scientists consider them to be a “double planet” rather than a planet-moon system
New Horizons will take advantage of Jupiter's gravity (planned 2007 flyby) which will boost the probe's velocity by 9,000 mph & get it to Pluto by 2015
Article on Why Pluto is No Longer Considered a Planet

16. Planetary Satellites What is a satellite?
an object that orbits a planet
Example of natural satellites?
moons
Example of artificial satellite?
TV satellite, GPS satellite, etc.

17. Planetary Satellites Earth  moon = only natural satellite
Mars  2 tiny irregularly shaped moons
Phobos
Deimos
Jupiter  at least 63 moons
4 largest
Galilean satellites (in honor of discoverer Galileo) Io
Europa
Ganymede
Callisto
Europa
Surface marked by crisscross pattern of bright & dark lines resemble cracks in ice floes in Earth’s polar oceans
Galileo mission took photographs & magnetic field data
Evidence that a liquid ocean 100 km deep may exist below the surface
If so, it is possible that life forms may have developed there perhaps getting energy from subsurface volcanic vents like those on Earth’s ocean floor

18. Planetary Satellites Saturn  at least 61 moons
Titan
only moon known to have substantial atmosphere
Uranus  at least 27 moons
5 major moons
Titania
Oberon
Umbriel
Ariel
Miranda
Neptune  at least 13 moons
Triton
Nile-Like River Found on Moon of Saturn (AMNH Sci Bulletin)

19. Minor Members of the Solar System Ch. 23.4
What are asteroids?
solid, rocklike masses probably left over from formation of solar system
How do asteroids orbit?
around sun in same direction as planets
most have nearly circular orbits within asteroid belt between Mars & Jupiter
Protecting Earth from Asteroid Impacts (AMNH Sci Bulletin)
some have collided with Earth… probably caused extinction of dinosaurs 65 mya

20. Minor Members of the Solar System
What are comets?
“dirty snowballs”
dust particles trapped in mixture of frozen water, carbon dioxide, methane, & ammonia
Where are comets usually found?
Most are Trans-Neptunian Objects (TNOs)
spend most of their time beyond Neptune’s orbit
Including in Kuiper Belt & Oort Cloud
Most comets come from the Oort Cloud and the Kuiper Belt.
TNOs = Any object in the solar system that orbits beyond Neptune

21. Minor Members of the Solar System
A few comets have highly elliptical orbits taking them closer to the sun
can become visible at night when icy surface is heated
Forms coma (cloud of gas & dust that expands into space)
tail points away from sun due to solar wind
Halley’s Comet
76 years
Comet Ison
When in normal orbit (in Kuiper belt & Oort cloud) consist only of solid main body (nucleus)
Halley’s Comet (after astronomer Edmund Halley who noticed & predicted pattern of return)
Returns to inner solar system every 76 years
Records of comet in 1531, 1607, 1682
Predicted return of comet in 1758/9
Returned again in 1835, 1910, 1986
Next return 2062
Comet Ison… first pass near Sun 11/28/2013

22. Minor Members of the Solar System
What are meteors, meteoroids, & meteorites?
rocky or icy fragments; smaller than asteroids
meteoroid
traveling in space
meteor
passing through Earth’s atmosphere
“shooting star”
meteorites
hit Earth’s surface
Large #s streak across night sky over a few hours = meteor shower
Earth passes through debris left by a comet & particles from tail plunge through atmosphere as meteors… B/c Earth’s orbit crosses path of comets around same time each year, many meteor showers predictable times… named for the constellation from which they appear to originate (ex. Perseids, happen in Aug., appear to come from constellation Perseus)
range in size from microscopic to kilometers in diameter
all originate inside our solar system. Most are fragments of small rocky and metallic bodies that broke apart long ago and orbit the Sun in the asteroid belt between Mars and Jupiter. Many orbit for millions of years before colliding with Earth.
contain a record of the conditions under which the early solar system formed some 4.6 billion years ago. By studying meteorites, we can learn details about how our solar system evolved into our Sun and planets, and how meteorite impacts could affect our future.

23. Minor Members of the Solar System
What are the 3 basic types of meteorites?
stony
iron
stony-iron
Give info about:
how solar system evolved
possible effects of impacts
Cape York Meteorite (Ahnighito)
Willamette Meteorite
Iron meteorites form when large enough asteroids have had molten interiors catastrophically collide with other asteroids. These huge collisions blast out material from the molten iron core of the asteroid on orbits that reach Earth after millions of years.
contain a record of the conditions under which the early solar system formed some 4.6 billion years ago. By studying meteorites, we can learn details about how our solar system evolved into our Sun and planets, and how meteorite impacts could affect our future.
Willamette Meteorite iron meteorite
weighs 15.5 tons
found in Oregon: largest ever found in U. S. & 6th-largest in world
smooth surface melted during its blazing entry into the atmosphere, while the pits formed on the Earth's surface.
The Cape York Meteorite (Ahnighito) iron meteorite
so heavy that supports from the largest of the three pieces go straight down to the bedrock beneath the Museum.
comes from the center of a small asteroid that broke apart.
4.5-billion-years-old (nearly as old as the Sun)
Discovered in 1894 in Greenland
slammed into Earth some 10,000 years ago.

24. Minor Members of the Solar System
What are impact craters?
bowl-shaped depressions that remain after meteor or other object hits Earth, other planet, moon
ejecta (debris) rays radiate out from crater
Arizona’s Barringer Meteor Crater
Rare features on Earth (only ~150 known)
Atmosphere burns up most meteoroids before they can hit the surface
Earth is geologically active so continuously “erasing” craters
Arizona’s Barringer Meteor Crater
One of youngest (formed ~49,000 years ago)
Iron meteorite ~45 meters in diameter struck Earth, exploded, left behind crater ~1200 meters in diameter