Educator’s Guide ARTHUR ROSS HALL OF METEORITES INSIDE • Essential Questions • Glossary • Collecting a Meteorite • Map of the Hall • Come Prepared Checklist • Continue Your Journey • Teaching in the Hall • Correlation to Standards • Fun Facts amnh.org/meteorites-educators ESSENTIAL Questions What are meteorites? reveal the rate at which the metal cooled. Since larger objects cool more slowly than small ones, scientists can Meteorites are rocks from space that survive a violent use this information to estimate the size of each passage through our atmosphere to land on Earth. All meteorite’s parent body. meteorites come from inside our solar system. Most are fragments of asteroids that have orbited the Sun What do craters between Mars and Jupiter for billions of years. A small number are pieces of rock from the surfaces of other tell us? planetary bodies, including the Moon. Other than Moon Since Earth’s formation some rocks brought back by the Apollo astronauts, meteorites 4.6 billion years ago, count- are our only samples of these other worlds. less meteorites have crashed into the planet. Some caused What do meteorites tell us about the dramatic changes, including birth of the solar system? at least one mass extinction. Taken by an Apollo 10 astronaut, Because of dynamic Earth this photo shows a few of the impact craters that record the Some primitive processes, only about 200 Moon’s history of asteroid meteorites, called impact craters have been bombardment. chondrites, are like found so far on Earth’s time capsules. current surface. Most craters have been erased by plate They have remained tectonics, while others have been hidden beneath lava, essentially unchanged ice, or oceans, or weathered away by wind and water. The since the solar system structure of craters tells us about the energy of their impact. formed, and scientists Being so close to Earth, the Moon has also been exposed to who study them can Seen under a microscope, the Allende asteroid bombardment. Unlike Earth’s surface, the Moon’s infer the age, composi- chondrite meteorite can be viewed in inactive surface shows traces of impacts that are billions of ordinary light (left) or in cross-polarized tion, and conditions of light (right), which helps scientists years old, making it the definitive record of that history. the early solar system. identify different minerals. Rounded Small white objects chondrules are embedded in a dark “matrix” made of tiny mineral grains, How do we collect and study inside these meteor- or “dust.” meteorites? ites are rich in calcium and aluminum. These calcium-, aluminum-rich inclusions, Scientists search for meteorites by traversing and systemati- or CAIs, are the oldest objects formed in our solar system. cally scanning promising areas. Meteorites are easiest to find Scientists have used radiometric dating to determine the in deserts, whether cold ones like Antarctica or hot ones like age of CAIs, and inferred that the solar system is at those of Africa and Australia, where they can be easy to spot least 4.568 billion years old. Chondrites contain tiny against sand or snow. Water causes meteorites to decay and near-spherical objects called chondrules, which likely rust, but they can survive a long formed when clumps of dust grains drifting in the solar time in dry conditions. Scientists nebula melted and then solidified rapidly. also search where impacts have been discovered, both recently and What do meteorites tell us about long ago. Once specimens reach the lab, scientists cut them into thin planets and asteroids? slices to study under microscopes. As the material in the inner solar system cooled, vapor They use CAT scans to determine condensed into solids. Small bodies accreted into larger three-dimensional structure and ones. These bodies collided with each other, and meteorite electron-beam instruments to Embedded in ice, fragments record this dramatic history. The largest bodies transported by glaciers, analyze mineral composition. To differentiated into cores and mantles. Meteorites that and eventually exposed establish the age of the samples, were formed by differentiation are called achondrites. Their at the surface, meteorites accumulate in certain researchers measure the ratios of chemistry is evidence that differentiation occurred widely parts of Antarctica, isotopes of certain elements that and on a large scale to form the planets of the inner solar where scientists have been collecting them undergo radioactive decay at system. Crystal-chemical patterns within iron achondrites for several decades. known rates. ARTHUR ROSS HALL OF METEORITES MAP THEATER 3a 3b 3c 3d 1e Allison and Roberto Mignone > Halls of Gems 1c and Minerals 2b 1a 1b 1d 4a 2a 4c 4b > Spitzer Hall of Human Origins CENTER AREA ORIGIN PLANETS IMPACTS 1a Thirty-Four Tons of Iron 2a Chondrules, CAIs, Matrix 3a Crust, Mantle, Core, 4a Earth Impacts Iron Crystals Parent Bodies, Meteor Crater 1b Fragments of Cape York 2b 4b Solar System, 3b Vesta 1c Stone and Iron from 4c On the Moon Planetesimals Space 3c Mars 1d What Does a Meteorite 3d Missions Look Like? 1e Looking Inside Meteorites © 2019 American Museum of Natural History. All rights reserved. Teaching in the Hall This hall uses specimens to investigate the origins of meteorites, their journey through space and fall to Earth, and the wealth of information they contain. The hall is laid out in a circle, with an overview in the center and three areas on an outer ring: “Origin of the Solar System” (primitive, or pre-planetary meteorites), “Building Planets” (material from planetary bodies, including sample return missions), and “Meteorite Impacts” (dynamics of the solar system). Numbers correspond to stops on the map. 1d. What Does a Meteorite Look Like?: THEATER: An eight-minute video gives an overview of the hall, During a meteor- exploring what meteorites are and what they tell us about the solar system. Topics include: what we can infer about Earth’s ite’s fall through the core from meteorites; the hazards of meteorites and how we can atmosphere, it heats stop them from hitting Earth; and how Museum scientists study up and melts on the meteorite and extraterrestrial samples. outside. Its ultimate appearance depends Miller Modoc on what it’s made of, One side of Miller stayed oriented how it came through CENTER AREA towards Earth as it passed through the atmosphere, and the atmosphere. It eroded into an what happened after aerodynamic “nose cone” shape, and OVERVIEW: The centerpiece of this hall is Ahnighito, one molten rock formed flow lines from impact. Students can front to back. Modoc’s broken surface of the three Cape York meteorites on display here. Touch- compare the external highlights its dark fusion crust, a thin, able specimens and text panels explain the characteristics appearances of several glassy coating that formed as its molten surface solidified before the meteorite of stony, stony-iron, and iron meteorites, and the history of meteorites to explore hit the ground. meteorite science. the effects of their high-speed journeys. GUIDED EXPLORATIONS 1a. Thirty-Four Tons of Iron: 1e. Looking Inside Meteorites: Scientists often cut Because it’s made of iron-nickel meteorites into thin petrographic sections to study their alloy, the Ahnighito meteorite is internal structure. Students can examine the slices and read much heavier than it looks. Students about what they reveal. can touch it and describe what they feel and see. (Tip: Look for the two polished spots; the criss-crossing ORIGIN pattern shows how the crystals grew.) Students can then read about OVERVIEW: Because Earth is dynamic, it has changed the difference between a meteor dramatically since the planet formed some 4.6 billion years (an object that enters Earth’s atmo- ago. Some meteorites, on the other hand, have remained sphere, usually disintegrating) and a The Woman, the Dog, unchanged as they travel through the vacuum of space, and Ahnighito (in rear). meteorite (material that survives the so they contain important information about physical and intense heat and pressure to land on Earth’s surface). chemical processes at work in the early solar system. The chondrite meteorites in this section are the most common 1b. Fragments of Cape York: Along with Ahnighito, types collected on Earth. these two meteorites, known as the Woman and the Dog, are fragments of a much larger meteorite that landed in GUIDED EXPLORATIONS Greenland thousands of years ago (see insert). Students 2a. These three cases “take apart” primitive meteorites into can watch the video to learn how they reached the Museum three components: and read text to learn about Arctic explorer Matthew • Chondrules: Under a microscope, these glassy beads are Henson, the first African American to explore Greenland. revealed in the thin section of Allende. Students can read 1c. Stone and Iron from Space: The most common type, about what the chemical composition of primitive stony meteorites are made of minerals that are similar to meteorites tells us about the solar system. those in rocks on Earth. Iron meteorites are more than 98% • CAIs: Calcium-aluminum inclusions are the oldest rocks metal. Stony-irons are a mixture of metal and rock. Students that formed in our solar system. Students can investigate can compare the polished surface of Estacado (stony; how scientists determine the age of mineral inclusions, different-sized grains) and Ahnighito (iron; regular pattern). and why that information is significant. • Matrix: Mineral dust from the early solar 3b. Vesta: Students can view specimens from Vesta, system has been preserved as matrix, a a differentiated asteroid that “lives” in the asteroid belt. dark, fine-grained material surrounding They can find out what the three types of HED (howardite- chondrules and CAIs. Students can explore eucrite-diogenite) meteorites tell us about the processes why some meteorites, such as Murchison, that shaped Vesta.