Origins: Earth is Born
The Hunt for Micrometeorites
To collect and identify micrometeorites from space.
- razor blade or modeling knife
- small plastic bags to store prepared slides
- 4 single-ply cereal boxes
- 4 plastic sandwich bags
- various-sized rocks (for weighting down collector)
- 1 light-colored shower liner
- 1 rigid plastic wading pool, about 1.5 meters in diameter (optional)
- duct tape (optional)
- 4 coffee cans (10 cm diameter;11.5 oz.) with bottom end cut out and plastic lids modified per instructions
- 4 junior size basket-style coffee filters (round base should be about 7 cm)
- 4 cereal box halves
- 16 microscope slides (2.5 cm x 7.5 cm)
- masking tape
- copy of the "The Hunt for Micrometeorites" student handout
- copy of the "Identifying Sky Dust" student handout
- spray bottle with trigger
- 1 cereal box half
- 4 microscope slides taped to cereal box half
- white glue, thinned 50 percent with water
- large plastic bag for storage
- microscope, with low (100x) and high (400x) power lenses, or stereomicroscope
- table lamp
Some scientists estimate that about 30,000 to 90,000 metric tons of space
dust and micrometeorites strike Earth yearly, mostly in the form of particles
less than a millimeter in size. These are remnants of the time when the solar
system formed about 4.6 billion years ago. In this activity, four student teams
will collect and identify sky dust over an eight-day period. (To shorten the
activity time period, you can increase the number of collectors or decrease the
number of times a single collector is deployed. Note, however, that the more
samples that are collected, the higher the probability of students finding a
Prior to class:
rinse the shower liner (to wash away any contamination)
hang it to dry vertically (to minimize dust contamination)
store it in a plastic bag (to protect it from contamination)
cut each of the four empty cereal boxes in half lengthwise (four halves
will be used for slide mounts, four halves will be used as the base on which
students will cut the wet coffee filter)
cut the bottom end from the four coffee cans and then cut the center from
the plastic can covers, leaving the lip and a half-centimeter rim
fill the plastic bags with rocks and seal them (these will hold down the
Assign students to make the filter assemblies and slide mounts (see
illustrations below). Alternately, you can construct these for students.
Filter: Filter devices can be made by carefully folding a coffee filter
evenly over the top of the can and securing it with the modified plastic cover.
Four filter devices should be made.
Slides: Place four microscope slides side-by-side on a piece of thin
cardboard and secure them with masking tape placed perpendicularly across both
ends of the slides. There should be no space between the slides. Four sets of
mounts should be made.
Review the instructions on the "The Hunt for Micrometeorites" student
handout. Organize students into four teams. Provide each team with a copy of
the handout and review the instructions with students. Tell students that each
team will take turns using the collector (light- colored shower liner) with
their filter device for a 48-hour period.
For the first round of collecting, have one of the teams place the
collector outside in an open location such as the middle of a lawn or open
field (if putting the collector in a plastic pool, use duct tape to secure the
four corners). Avoid areas that are exposed to gusty winds, (such as building
corners) and contamination from sources (such as falling tree leaves and road
spatter). Avoid rainy days. Time of day is unimportant.
Leave the collector out for 48 hours. If high winds or rain are
forecast, temporarily move the collector inside. Store the collector by folding
it in half (if using pool) or placing it in the plastic bag so that no dust
settles on it. Have students look at the collector after 24 hours; if detritus
is visible, students can collect the particulate matter at that time.
Provide the first team with a set of collection materials and have team
members use the retrieval method outlined in their handouts to collect any
particulate matter that has fallen into the collector. If the shower liner is
taped to a plastic wading pool, make sure that students do not shake the sheet
as they carefully cut the duct tape securing the shower liner to the pool.
Have the first team prepare its slides, making sure that team members only
very thinly coat their slides with the watered-down glue. If too much glue is
used, it will impart a gloss that makes micrometeorite identification more
After the slides have dried, use a razor blade or modeling knife to separate
them by cutting through the filter material. Choose and store in a plastic bag
the slides that have the most particulate matter (not all the slides will have
particulate matter on them; four slides are used to allow for a margin of error
for students placing the filter on top of them). Repeat the collection
procedure with all of the teams.
Once all the teams have retrieved particles from the collector, have
students view their findings. If using a compound microscope, have students
position a table lamp slightly above the microscope stage. What do students see
on their slides? How many different kinds of particles do they see? Have
students record the particles they see on their "Identifying Sky Dust" student
handout. Work with students to identify as much as possible on their slides.
(See Activity Answer for a list of Web sites that contain photos of
micrometeorites and other particulate matter that may be found.) Where do
students think each of the identifiable particles came from?
As an extension, have students research the origins of the solar system's
asteroids and meteorites and write a one-page summary describing the
differences between them, where they come from, how they are studied, and what
information they can reveal about the universe.
Identify minerals and consider what information they can reveal about the
planet from which they came.
Learn how Earth was born and how meteorites are found in this American Museum
of Natural History site that offers articles and student materials related to
NOVA's "Earth Is Born" program.
Using a Plastic Wading Pool
Although not required for this activity, a plastic wading pool is
recommended. The pool will prevent the shower liner from flapping in the wind
and help keep students from accidentally stepping on the liner. A pool will
also allow the collector to remain relatively undisturbed (flapped or shaken)
fit needs to be moved indoors because of high winds or a rain storm.
For additional setup photographs, see www.pbs.org/nova/teachers/activities/3111_origins_03.html
While most of the material students collect likely will be terrestrial sky
dust, it is possible that students may find one micrometeorite in the collector
each night. If students do not find any micrometeorites, you may want to
lengthen the collection period or try a different venue. See the following Web
sites for photos of micrometeorites and other sky dust:
Here are some items that have been found by U.S. teams participating in the
National Aeolian Detritus Project, a pilot National Science Foundation project
to collect and identify sky dust:
These can be composed of rock, metal (nickel and iron), or both. The majority
of the micrometeorites are made of rock, although these are more difficult to
identify than metal micrometeorites, which look small, shiny, etched, black,
and more or less round. Metal micro- meteorites will respond to magnets.
Although micrometeorites come in a range of sizes (from about 10 microns to 500
microns), the smaller sizes are more common.
Similar to micrometeorites except that they are dull black and lumpy. Formed
when a commercial boiler uses steam to dislodge carbon buildup.
Almost always present in various shapes and sizes. Find U.S. regional pollen
season information at www.aaaai.org/nab/index. cfm?p=uspollen_seasons
Sometimes parts of insects will show up in collectors. For example, ant wings
left from spring mating flights.
Gypsy moth instars (young form) show up in the collectors before their presence
is detected by other means.
Unusual amounts of illite, a kind of clay particle, were detected in New
England collectors two weeks after a large dust storm in Mongolia. The actual
arrival time matched the arrival time predicted by computer models.
A team in Massachusetts found "Christmas trees"—clumps of small splinters
with little balls at their tips. The team thought they might be a new form of
micro- meteorite when they discovered that a magnet attracted them. Careful
checking revealed that the collector was near a body shop and that the
"Christmas trees" were partially oxidized steel grindings. Another team found
long tubes running all over a filter. They turned out to be hyphae, the
vegetative body of a fungus that grew on the filter after it had been processed
and left damp for too long.
NOVA Web Site—Origins
In this companion Web site to the program, find out how life could have
started and why water is needed for life; read about the latest discoveries in
origins research; use raw data to assemble the famous Eagle Nebula image;
insert your own values into the Drake Equation; decode cosmic spectra; and
Age of the Earth
Explains radiometric dating methods used by scientists to estimate the age of
Exploring Meteorite Mysteries
Provides information and activities related to meteorites and their origins
from such places as Mars, asteroids, and the moon.
Magnetic Field of the Earth
Examines the Dynamo Effect and its relevance to the formation of Earth's
National Aeolian Detritus Project
Details a project in which students discover micrometeorites and other
materials by collecting and identifying sky dust.
The Origin of the Moon
Explores in detail the leading theory of how the moon formed, including factors
supporting the theory and its development.
Life's Matrix: A Biography of Water.
New York: Farrar, Straus and Giroux, 1999.
Tells of the possible origins of water—its history, pervasiveness and
potential presence on other planets.
Asteroids, Comets, and Meteors.
New York: Twenty-First Century Books, 1996.
Compares asteroids, comets, and meteors and provides a range of general
information on the solar system, the galaxy, and the universe.
The "The Hunt for Micrometeorites" activity aligns with the following
National Science Education Standards:
Science Standard D:
Earth and Space Science
Earth in the solar system:
The Earth is the third planet from the sun in a system that includes the
moon, the sun, eight other planets and their moons, and smaller objects, such
as asteroids, and comets. The sun, an average star, is the central and largest
body in the solar system.
Science Standard D:
Earth and Space Science
The origin and evolution of the Earth system:
Classroom Activity Author
James Sammons has taught middle and high school science in Rhode Island for 30
years. His teaching practices have been recognized by the National Science
Teachers Association, the Soil Conservation Service, and the National
Association of Geoscience Teachers.