Hunt for the Killer Asteroid
An Asteroid Timeline Activity
Objectives
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Students will create a timeline and place major impact events correctly on
the timeline

Students will read and decipher information and create a hypothesis

Students will gather and use information to support their hypothesis

Students will use that information to draw conclusions based on scientific
facts and hypotheses

Students will use latitude and longitude to find places on a map

Students will use math to order large numbers

Students will use math to compare numbers
Suggested Grade Level
5th-8th
Subject Areas
Science
Geography
Math
Timeline
One to two class periods
Standards
Science as Inquiry

Abilities necessary to do scientific inquiry

Understanding about scientific inquiry
Physical Science

Properties and changes of properties in matter

Motions and Forces

Transfer of Energy
Life Science

Diversity and adaptations of organisms
Earth and Space Science
Image courtesy of BBC



Earth’s history
Earth in the solar system
Origin and evolution of the Earth system
Science and Technology

Understanding about science and technology
Science in Personal and Social Perspectives

Populations, resources, and environments

Natural hazards

Risks and benefits

Science and technology in society
History and Nature of Science

History of science
Geography
The World in Spatial Terms

How to use maps and other geographic representations, tools, and
technologies to acquire, process, and report information

How to use mental maps to organize information about people, places,
and environments

How to analyze the spatial organization of people, places, and
environments on Earth's surface
Physical Systems

The physical processes that shape the patterns of Earth's surface
The Uses of Geography

How to apply geography to interpret the past

To apply geography to interpret the present and plan for the future
Math
Geometry

Make and use coordinate systems to specify locations and to describe
paths
Background
Teachers must provide students with a background of asteroid history. The first
asteroid to be discovered was Ceres. Giuseppe Piazzi discovered Ceres on
January 1, 1801. His first conclusion was that it was a star. As he continued to
observe Ceres he noticed that it moved across the sky. This meant it couldn’t be
a fixed star. He later concluded that it must be a comet; however, it didn’t have
the common nebulous of a comet. He, then, supposed it must be something new.
He called it a “minor planet.” Later calculations allowed others to find and track
Ceres and confirm Piazzi’s assumption that it was something new.
Since the first discovery of Ceres, over 300,000 asteroids have been discovered.
The current rate is about 5,000 per month. Most of these asteroids are in the
asteroid belt. The asteroid belt is located between the orbits of Mars and Jupiter.
Many scientists believe the asteroid belt is a planet that failed to form due to the
intense gravitational pull of Jupiter. Some asteroids, though, are not located in
the asteroid belt. They can be found orbiting the sun in different locations around
the solar system.
Scientists have concluded that several such asteroids or meteorites have struck
the Earth throughout its history. One such clue is the surface of the Moon. The
Moon is pocked with impact craters. With its proximity to Earth there is no doubt
that the Earth has been struck as many, if not more, times as the Moon due to
Earth’s strong gravitational pull and size.
So, where are these impact craters? Earth’s natural forces such as weathering,
erosion, and deposition have worn away most impact craters around the globe.
Plate tectonics have also contributed to the destruction of these craters. The
Earth is constantly recycling its crust, and with it, any clues to impact craters of
the past. It is only with new and advanced technology that we can even locate
some of these collisions. Using satellites that detect underground magnetic
anomalies, scientists are unraveling the clues to Earth’s violent past.
One such historic incident was an impact in the Yucatan Peninsula at a place
called, Chixculub. This impact crater was discovered using satellites because
the evidence of the impact is buried far underground. This impact, which
occurred 65 million years ago, is thought to have wiped out the dinosaurs.
Recent evidence suggests that huge tsunamis traveled all along the Gulf Coast
and reached far inland in Mexico and Texas. The force was so great that it
jumbled the fossil record in those areas. Why do scientists think that this was
the killer asteroid? Evidence called the K-T Boundary layer is found around the
entire globe at approximately the same depth. Diagnosis of this layer shows that
it is rich in sulfur. The Chixculub area, where the asteroid hit, is a sulfur-rich
area. This sulfur has been observed in the K-T Boundary all over the Earth.
When the asteroid hit, it not only shot dirt and molten Earth into the air, but
poisonous sulfur gas which further hampered the dinosaurs fight for survival.
Another recent discovery, in Antarctica, has possibly yielded another “Earthkiller.” The Wilkes Land impact crater, also detected by satellite, was so
devastating that scientists believed it wiped out most life on Earth about 250
million years ago. The force of the impact was so immense, scientists believe it
may have been one of the causes to break up the Gondwana super-continent,
and sent Australia floating away on its own. They also believe that the mass
extinction caused by this impact made it possible for the dinosaurs to eventually
evolve.
So the question for scientists is when will the next impact occur?
The purpose of this lesson is to familiarize the students with asteroids and the
impact they have on the Earth. The students’ mission is to discover which
asteroid crater is the evidence of the asteroid that killed the dinosaurs. It may be
beneficial to create a timeline before the activity and fill in the timeline after the
activity.
Materials
Adding machine tape (or strips of construction paper), computers with Internet
connection (this activity can be done without the Internet or Google Earth),
Google Earth, maps of the world for each student or group
Extension Materials
Plastic sheets or trash bags that have been cut apart, aluminum pans, flour,
cocoa powder, various sized marbles
Lesson
1. Pre-assessment of prior knowledge can be an introduction. Questioning
students on Earth science knowledge can give the teacher an idea of prior
student knowledge. Also, using a K-W-L tool can be useful in assessing
prior knowledge.
2. Introduce the lesson to the students. Today they are going to try to solve a
mystery that is millions of years old. We have to find out what crater
impact site was the one that caused the extinction of the dinosaurs.
3. Ask students how long ago the dinosaurs died out. Answer:
Approximately 65 million years ago.
4. Note: An asteroid must be at least ½ mile in diameter to cause a mass
extinction. This means the crater, depending on the asteroid’s velocity,
would need to be at least four to nine miles wide.
5. Give a background of asteroids and asteroid impacts on Earth. Ask the
students why we can see impacts on the Moon and Mars, but not on
6.
7.
8.
9.
Earth. Answer: The Earth’s natural forces of weathering, erosion, and
deposition erase evidence of craters. Plate tectonics and lava floes also
cover up traces of asteroid impacts.
Explain to students that there are theories that asteroids, impacting the
Earth, have been responsible for various extinctions throughout Earth’s
history.
Give students the list of impact craters. On a world map, have the
students locate where each crater is located and mark it. They may also
identify the craters using Google Earth and the latitude/longitude feature.
On adding machine tape, or construction paper strips, have the students
make a timeline from 300 million years ago to the present. (The timeline
may not be proportionate. If you desire a timeline to scale, students can
create one on the floor or in the hall.)
Add the impact craters to the timeline in the proper sequence.
10. Using the clues, have students determine which impact crater may have
been responsible for killing the dinosaurs. Students will complete the
Suspect Killer Asteroid worksheet. They will state which asteroid impact
crater they concluded is the culprit, the location of the crater, and the
latitude and longitude of the crater. After completing that data, they will fill
in the evidence section of the worksheet. Students will cite the crater’s
diameter, the age of the crater and conclude why they feel their suspect is
the correct villain.
11. Now it is time to add one more asteroid: Apophis.
12. Apophis may strike the Earth in 2036, but it is not likely. Ask the students:
Is Apophis big enough to create a mass extinction? Answer: No. Why?
Apophis is too small to cause a mass extinction.
13. Apophis will strike somewhere between Hawaii and California in the
Pacific Ocean. Have students give a probable latitude and longitude
coordinate where the impact could occur.
Extensions
You can have students experiment with impact craters by creating a fictitious
planet surface for them.
1. Lay out the plastic sheets on the floor.
2. Lay the aluminum pan on the plastic sheet.
3. Fill the bottom of an aluminum pan with flour, about one inch deep.
4. Cover the flour with a thin layer of cocoa powder (just enough to
completely cover the flour.)
5. Have students drop a marble into the pan from a height of about three
feet.
6. Have students draw what they see. (This is a good time to talk about
vocabulary such as ejecta, and crater rim.)
7. Drop another marble into the pan. Ask students what happened to their
first crater.
8. Have students experiment with various sizes of marbles. How does that
change the size of the crater?
9. You can also have your students experiment with various trajectories and
velocities. How does that change the size and shape of the crater?
10. By doing this, you can also have students try to determine which craters
are the oldest and which ones are the youngest. (The youngest craters
will have their ejecta covering older craters. Also, older craters will have
their crater rims starting to break down, whereas younger craters will have
a much more defined crater rim.)
Evaluation/Assessment
Students can be graded on the accuracy of their hypothesis and the details that
were given to support their hypothesis.
Resources
National Science Standards: http://www.nap.edu/readingroom/books/nses/
National Geography Standards:
http://www.ncge.org/publications/tutorial/standards/
National Math Standards: http://standards.nctm.org/document/index.htm
Wikipedia.com: http://www.wikipedia.com
Solarviews.com: http://www.solarviews.com/eng/tercrate.htm
Google Earth can be downloaded at this site: http://earth.google.com/
The Suspects
Aorounga, Chad, Africa
19°6'N, 19°15'E; diameter: 17 kilometers (10.6 miles); age: 200 million years
The impact of an asteroid or comet several hundred million years ago left scars
in the landscape that are still visible in this spaceborne radar image of an area in
the Sahara Desert of northern Chad. The original crater was buried by
sediments, which were then partially eroded to reveal the current ring-like
appearance. The dark streaks are deposits of windblown sand that migrate along
valleys cut by thousands of years of wind erosion. The dark band in the upper
right of the image is a portion of a proposed second crater. Scientists are using
radar images to investigate the possibility that Aorounga is one of a string of
impact craters formed by multiple impacts.
Barringer Meteor Crater, Arizona
35°02'N, 111°01'W; diameter: 1.186 kilometers (.737 miles); age: 49,000
years
The origin of this classic simple meteorite impact crater was long the subject of
controversy. The discovery of fragments of the Canyon Diablo meteorite,
including fragments within the breccia deposits that partially fill the structure and
a range of shock metamorphic features in the target sandstone proved its impact
origin. Target rocks include Paleozoic carbonates and sandstones; these rocks
have been overturned just outside the rim during ejection. The hummocky
deposits just beyond the rim are remnants of the ejecta blanket. This aerial view
shows the dramatic expression of the crater in the arid landscape. (Courtesy of
USGS/D. Roddy and LPI)
Bosumtwi, Ghana
06°32'N, 01°25'W; rim diameter: 10.5 kilometers (6.5 miles); age: 1.3 +- 0.2
million years
This crater is situated in crystalline bedrocks of the West African Shield and is
filled almost entirely by Lake Bosumtwi. Chemical, isotopic, and age studies
demonstrate that the crater is the most probable source for the Ivory Coast
tektites, which are found on land in the Ivory Coast region of central Africa and as
microtektites in nearby ocean sediments. In this photo, the crater lake is partly
obscured by clouds. (Courtesy NASA/LPI)
Chicxulub, Yucatan Peninsula, Mexico
21°20'N, 89°30'W; diameter: 170 km (105.6 miles); age: 64.98 million years
This three-dimensional map of local gravity and magnetic field variations shows a
multi-ringed structure called Chicxulub, named after a village located near its
center. The impact basin is buried by several hundred meters of sediment, hiding
it from view. This image shows the basin viewed obliquely from approximately
60° above the surface looking north, with artificial lighting from the south. The
image covers 88 to 90.5° west longitude and 19.5 to 22.5° north latitude. NASA
scientists believe that an asteroid 10 to 20 kilometers (6 to 12 miles) in diameter
produced this impact basin. The asteroid hit a geologically unique, sulfur-rich
region of the Yucatan Peninsula and kicked up billions of tons of sulfur and other
materials into the atmosphere. Darkness prevailed for about half a year after the
collision. This caused global temperatures to plunge near freezing. (Image
courtesy of V. L. Sharpton, LPI)
Clearwater Lakes, Quebec, Canada
Clearwater Lake West: 56°13'N, 74°30'W; rim diameter: 32 kilometers (20
miles)
Clearwater Lake East: 56°05'N, 74°07'W; rim diameter: 22 kilometers (13.7
miles)
age: 290 +- 20 million years
These twin circular lakes (large dark features) were formed simultaneously by the
impact of an asteroidal pair which slammed into the planet approximately 290
million years ago. The lakes are located near the eastern shore of Hudson Bay
within the Canadian Shield in a region of generally low relief in northern Quebec
province. Notice that the larger western structure contains a ring of islands with a
diameter of about 10 kilometers that surrounds the center of the impact zone.
They constitute a central uplifted area and are covered with impact melts. The
central peak of the smaller Clearwater Lake East is submerged. The lakes are
named after their exceedingly clear water. Also notice that the surrounding
terrain shows widespread scarring from glaciation. The multitude of linear and
irregular shaped lakes (dark features) are the result of gouging or scouring action
caused by the continental ice sheets that once moved across this area.
(Courtesy NASA)
Deep Bay, Saskatchewan, Canada
56°24'N, 102°59'W; rim diameter: 13 kilometers (8 miles); age: 100 +- 50
million years
This crater consists of a near-circular bay, about five kilometers (three miles)
wide and 220 meters (720 feet) deep, in the otherwise shallow Reindeer Lake.
Such deep circular lakes are unusual in this region, which is dominated by the
shallow gouging of glacial erosion. The circular shoreline, at a diameter of 11
kilometers (6.8 miles), is partially surrounded by a ridge with heights to 100
meters (328 feet) above the lake surface. The diameter of this ridge, ~13
kilometers (8 miles), is likely the outer rim of the impact structure. The structure
was formed in Precambrian metamorphic crystalline rocks with a conspicuous
northwest trending fabric. Although not obvious from the surface, Deep Bay is a
complex impact structure with a low, totally submerged central uplift. Samples
obtained in the 1960's from drilling into the central structure revealed shocked
and fractured metamorphic rocks flanked by deposits of allocthonous, mixed
breccias. (Courtesy NASA/LPI)
Gosses Bluff, Northern Territory, Australia
23°50'S, 132°19'E; rim diameter: 24 kilometers (15 miles); age: 142.5 +- 0.5
million years
142 million years ago, an asteroid or comet slammed into what is now the
Missionary Plains in Australia's Northern Territory, forming a crater 24 kilometers
in diameter and five kilometers deep. Today, like a bull's eye, the circular ring of
hills that defines Gosses Bluff stands as a stark reminder of the event. The crater
is located just south of MacDonnel Ranges (top of the picture). It is highly
eroded. The circular ring of hills (five kilometers or three miles diameter) is
actually the result of differential erosion of the central uplift within this large
complex crater. The crater rim is eroded to the point that it is no longer visible
though it is probably located along the grayish colored drainage system outside
the inner ring. (Courtesy USGS)
Kara-Kul, Tajikistan
38°57'N, 73°24'E; rim diameter: 45 kilometers (28 miles); age: <10 million
years
The spectacular Kara-Kul structure is readily apparent in this image. Partly filled
by the 25-kilometer (16-mile) diameter Kara-Kul Lake, it is located at almost
6,000 meters (20,000 feet) above sea level in the Pamir Mountain Range near
the Afghan border. Only recently have impact shock features been found in local
breccias and cataclastic rocks. (Courtesy NASA/LPI)
Manicouagan, Quebec, Canada
51°23'N, 68°42'W; rim diameter: ~100 kilometers (62 miles); age: 212 +- 1
million years
The Manicouagan impact structure is one of the largest impact craters still
preserved on the surface of the Earth. This shuttle view shows the prominent 70
kilometers (43 miles) diameter, ice-covered annular lake that fills a ring where
impact-brecciated rock has been eroded by glaciation. The lake surrounds the
more erosion-resistant melt sheet created by impact into metamorphic and
igneous rock types. Shock metamorphic effects are abundant in the target rocks
of the crater floor. Although the original rim has been removed, the distribution of
shock metamorphic effects and morphological comparisons with other impact
structures indicates an original rim diameter of approximately 100 kilometers (62
miles). (Courtesy NASA/LPI)
Mistastin Lake, Newfoundland and Labrador, Canada
55°53'N, 63°18'W; rim diameter: 28 kilometers (17.4 miles); age: 38 +- 4
million years
This shuttle image shows a winter view of the Mistastin Crater, a heavily eroded
complex structure. Eastward moving glaciers have drastically reduced the
surface expression of this structure, removing most of the impact melt sheet and
breccias and exposing the crater floor. Glacial erosion has also imparted an
eastward elongation to the crater that is particularly evident in the shape of the
lake that occupies the central 10 kilometers (six miles) of the structure.
Horseshoe Island, in the center of the lake, is part of the central uplift and
contains shocked Precambrian crystalline target rocks. Just beyond the margins
of the lake are vestiges of the impact melt sheet that contain evidence of
meteoritic features in quartz, feldspar and diaplectic glasses. (Courtesy
NASA/LPI)
Roter Kamm, SAR-C/X-SAR Image
27°8'S, 16°2'E; rim diameter: 2.5 kilometers (1.55 miles); age: Five million
years
This space radar image shows the Roter Kamm impact crater. The crater rim is
seen as a radar-bright, circular feature. The bright white, irregular feature in the
lower left corner is a small hill of exposed rock outcrop. Roter Kamm is a
moderate sized impact crater, 2.5 kilometers (1.55 miles) in diameter, and is 130
meters (427 feet) deep. However, its original floor is covered by sand deposits at
least 100 meters (328 feet) thick. In a conventional aerial photograph, the brightly
colored surfaces immediately surrounding the crater cannot be seen because
they are covered by sand. The faint blue surfaces adjacent to the rim might
indicate the presence of a layer of rocks ejected from the crater during the
impact. The darkest areas are thick, windblown sand deposits which form dunes
and sand sheets. The sand surface is smooth relative to the surrounding granite
and limestone rock outcrops and appears dark in the radar image. The green
tones are related primarily to larger vegetation growing on sand soil, and the
reddish tones are associated with thinly mantled limestone outcrops. (Courtesy
NASA/JPL)
Wilkes Land Impact, GRACE Image
70°S, 120°E; rim diameter: 482.9 kilometers (300 miles); age: 250 million
years
The crater is more than 300 miles wide and was made about 250 million years
ago by an asteroid nearly 30 miles wide. Researchers say that it may have
caused an Earth-wide Extinction Level Event (ELE), but also may have created
the conditions under which dinosaurs evolved. The species that benefited include
the archosaurs, the immediate ancestors of the dinosaurs.
It is thought that nearly 96% of Earth's ocean life and at least 70% of animals on
land were made extinct. The impact itself may also have caused the
supercontinent Gondwana to break, ultimately forming Australia.
Wolfe Creek, Australia
19°10' S, 127° 48' E; rim diameter: 0.875 kilometers (.544 miles); age:
300,000 years
Wolfe Creek is a relatively well-preserved crater that is partly buried under wind
blown sand. The crater is situated in the flat desert plains of north-central
Australia. Its crater rim rises ~25 meters (82 feet) above the surrounding plains
and the crater floor is ~50 meters (164 feet) below the rim. Oxidized remnants of
iron meteoritic material as well as some impact glass have been found at Wolf
Creek. This photograph is a south-looking, oblique aerial view of the crater.
(Courtesy of V. L. Sharpton, LPI)
Apophis
99942 Apophis (previously known by its provisional designation 2004 MN4) is a
Near-Earth asteroid that caused a brief period of concern in December 2004,
because initial observations indicated a relatively large probability that it would
strike the Earth in 2029. However, additional observations provided improved
predictions that eliminated the possibility of an impact on Earth or the Moon in
2029. There remains a possibility that during the 2029 close encounter with
Earth, Apophis would pass through a "gravitational keyhole," which would set up
a future impact on April 13, 2036. This possibility kept the asteroid at Level One
on the Torino impact hazard scale through August 2006.
The Suspect Killer Asteroid
Name _____________________
Date ______________________
My Suspect
Crater Name: _____________________________________________________
Location: ________________________________________________________
Latitude & Longitude: ______________________________________________
The Evidence
Crater Diameter: __________________
Age: ______________________
Conclusion: ______________________________________________________
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