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Section 1 -Guided Notes:
I.
Asteroids –
a. What is an asteroid?
Rocky objects left over from the formation of the solar system
b. Sometimes called:__Minor Planets___
c. Locations
i. NEA – Near Earth Asteroids
1. Definition:
Asteroids that cross the orbit of Earth.
2. Examples:
Eros, 1950 DA, Apophesis
ii. Main Belt
1. Asteroids that orbit between Mars and Jupiter
Most asteroids are found here
2. Largest Asteriod- Ceres – 580 mile in diameter
iii. Trojans
1. Asteroids that are trapped in Jupiters Lagrange Point
2. Lagrange PointsA gravitational stability zone 60 degrees in front and behind the orbit of a planet.
Since jupiter is the largest planet, it has many asteroids trapped in its Lagrange
point.
Earth’s Lagrange point has many man made satellites in it, such as the Soho space
craft.
d. Types:
i. C-type
1. Composition- Carbon
2. Color- Very Dark in color (like Coal)
3. Percent- Up to 75% of asteroids are C-type
4. Primitive – Primitive means the asteroid is unchanged since it formed. It hasn’t
melted, and still preserves information from the formation of the solar system
ii. S-Type
1. Composition- Silicated (most Earth rocks are also Silicate in nature)
2. Color- Light in color
3. Percent- 15% of asteroids are S-type
4. Primitive/Differentiated- Some are primitive, and some are differentiated.
Differentiated – They have changed since they formed, i.e. melted. Some contain lava
flows.
iii. M-Type
1. Composition- Metal
2. Origin- These were produced from shattered cores of large asteroids.
The pressure in large asteroids cause the inside to heat, and melt. The dense metal
settles to the core. If the asteroid collides and breaks, fragments from the core can
form. These fragments are M-type asteroids.
3. Color- Very bright in color (metal)
4. Percent- rare ~ 5-10%
5. Differentiated- These have melted, so they are differentiated.
Section 2 - Objectives:
1. SWBAT describe meteors
2. SWBAT define and describe the impacts of meteors
Guided Notes:
I Meteorites: Pieces of asteroids that fall to Earth.
* Pieces of comets also fall, but they are ice, and therefore do not produce ground debris.
e. How much falls to earth?
About 40,000 -80,000 Tons per year
f.
What size are most of the meteors that crash into earth?
Most of this is in the size of DUST particles
g. Types of Meteorites:
i. Stoney
1. Composition- Rock – Silicates and/or Carbon
2. These are the most common type of meteors to fall to Earth
3. Although they are the most common to fall to Earth, they look very similar to Earth
rocks, and therefore are VERY difficult to find.
4. Chondrules- Spherical pieces left over from the formation of the solar system. They
are debris left from what formed our planets. They are often found embedded in
primitive objects, such as Stony Meteorites.
ii. Iron
1. Composition- Metal (Usually Iron and Nickel)
2. These fall to Earth much less often, however, since they are metal, they look
different from Earth rocks, and are easy to find with metal detectors. Therefore,
they are the most commonly found meteorites. – (These are what people typically
think of when they imagine meteorites)
Differentiated – They are differentiated, they are fragments of M-type asteroids.
iii. Stoney-Iron
1. Composition- Mix of rock and metal
2. These pieces are from the boundaries between the metal core and the rocky crust of
large asteroids
3. They are very rare to fall to Earth. Hoever, since they are partially metal, they are
still easier to find (using metal detectors) than stony meteorites
h. Locations
i. Desert
Deserts have very little erosion, so any meteorite that falls does not erode away.
Also, they are barren compared to other environments, so it’s easy to use a metal detector and
search for meteorites in them.
ii. Antarctica
Antarctica is technically a Desert, it receives very little precipitation.
Also, the meteors contrast with the snow
Finally, Glaciers tend to pile the meteors up (like bulldozers).
Section 3 - Objectives:
- SWBAT describe the impact of meteorites on the earth
Guided Notes:
II.
Terrestrial Impacts
a. Frequency of Impacts: Small meteors hit the Earth Daily, but usually cause no damage. However, larger
ones do hit:
1. Energy of a nuclear explosion
A few times per year (Usually size of a refrigerator)
These are small enough that they almost always break up in the upper atmosphere (Airburst), and
therefore do not cause damage.
2. Energy of a few hundred to 1000 nuclear explosions
Perhaps every 100 years?
These ones are around the size of a large car to a building.
They also often break up in the atmosphere (Airburst), and do not leave craters.
However, sometimes they explode close to the ground and cause damage.
Ex: Tunguska
This is the largest to hit in around 100 years. It was about the size of a house.
1908 – It was seen entering our atmosphere over Siberia. People could see it for 100’s of miles. It
eventually exploded 6 miles above the ground in Tunguska. The resulting explosion had the energy of 1000
Hiroshima nuclear bombs. It leveld approximately 1000 square miles of forest, sent a pressure wave that traveld
around Earth twice, caused an Earthquake that could be feld throughout Asia and Europe, and sent a vapor cloud
into the upper atmosphere that lit up the sky. People could read newspapers at night by the vapor light alone.
Recent research suggests it was a Comet fragment, and not an asteroid.
3. Energy of thousands of nuclear explosions
These objects are 100’s of feet across. They hit Far less often. Maybe every 10,000 – 50,000 years?
Ex: Barringer Crater
This famous example is in Arizona. It hit about 50,000 years ago, and left a crater the size of ______.
The impact would have vaporized life for 100’s of miles around, and launched dust that would have covered the
Earth for a few years.
It’s one of the best preserved craters in North America.
Ex2: Chesapeake Bay Bolide
This is a larger example. It hit where the Chesapeake bay is today and left a ~100 mile wide crater.
It hit approximately 32 million years ago and would have vaporized life all along the Atlantic Coastal
Plain
The crater depression diverted the surrounding rivers and actually created the Chesapeake bay.
The crater has since filled in and is now underground, but people living in this area often have problems
with water and land subsidence, due to the shattered rock underneath them.
4. Energy of millions of nuclear explosions
Asteroid impacts of this size are VERY rare. They hit perhaps every 10 – 50 million years, and can cause
massive global devastation. – Global tsunamis, Global fire storms, “Nuclear Winters” due to debris
blocking the sun for years.
Ex: Chicxulub Crater
Most Famous Impact – Hit 65 million years ago, helped bring Dinosaurs to extinction.
Impacted in the Gulf of Mexico.
Ex: Manicouagan Crater
Large crater preserved in Canada.
Ex: Vredefort Crater
Largest crater found on Earth. Found in Africa
III.
Crater Structure:
a. Crater Rim
The rim of the crater, the impactor scoops out a hole, there is usually a rim around the hole.
b. Central Uplift
When the imipactor hits, it hits with such force, that the energy bounces back up, causing the
center of the crater to be lifted up.
c. Ejecta Blanket
Layer of debris from the impactor laying around the crater
d. Breccia
Crushed rock underneath the crater. The impactor smashes the underlying bedrock.
e. Tektites
The impactor hits with such energy, it melts the rocks. In mid-air, the rocks re harden, forming
raindrop, or teardrop like shapes.
f.
Shocked Quartz
Found under the crater, the impactor smashes minerals, compressing them, and changing their
properties. Quartz is the most common mineral.
Section 4- Objectives:
- SWBAT describe the comet
Guided Notes:
1. Comet Basics
a. What is a comet?
Object composed of a mix of Ice and dust left over from the formation of the solar system.
b. Comet’s partsl
i. Nucleus – the Actual comet, the actual chunk of ice.
ii. Coma – When a comet gets close to the sun, it warms up. The volatile elements in the ice
start to melt, which forms a vapor cloud around the nucleus.
iii. 2 Tails - When a comet gets close to the sun, it starts to melt. The coma begins to blow away
due to the solar wind, and a tail forms. A tail always faces away from the sun, since the suns
wind blows it away.
1. Dust : A tail of dust from the coma being blown away
2. Ion : The soalr wind will hit and charge some of the dust particles, giving them electric
and magnetic properties. These particles will bend toward the magnetic field of the
sun.
2. Locations of comets
a. Oort Cloud
Large sphere of comets that
surround our solar system. They
are at the Far edge of the solar
system. It conatins millions of
comets.
b. Kuiper
A belt of comets just past the
orbit of Neptune.
Pluto is considered a Kuiper belt
comet.
3. Kuiper Belt Objects
a. Eris (Xena) – Largest Kuiper belt object discovered. This icy body is slightly larger than pluto.
b. Pluto – Another large Kuiper belt object, Composed of mostly Ice.
c. Orcus – 3rd Largest Kuiper belt object discovered.
4. Meteor Showers:
Occur when the Earth passes THROUGH the orbit of a comet. The comets orbit is littered with debris (dust).
As the Earth passes through, it hits into this debris (dust). We see the dust impacts as streaks of light in the
sky.
The Earth passes through the orbits of various comets each year. Each year we have the same meteor showers.
Meteor showers are named after the constellation they appear to come from.
5. Zodiacal light
Dust in the solar system can be seen on dark nights because the sunlight reflects off of it. It looks like a faint
red glow that follows the ecliptic. Most of the dust in this
6. Importance of Studying Comets:
Comets are Primitive, they are left over from the formation of the solar system. So astronamers can study
them to learn about the origional material that formed the solar system.