Notre Terre Observer, mesurer et modéliser notre Terre pour mieux la comprendre, la gérer et l'enseigner, résume la vision des sciences de la Terre à l'institut de physique du globe de Paris. Cette approche scientifique conçoit les géosciences dans leur globalité, depuis la surface du globe aux profondeurs de la Terre interne, et ce à toutes les échelles, en temps ou dans l'espace. L'aspect pluridisciplinaire des recherches est fortement développé à l'IPGP afin de répondre aux grandes questions posées par la l'étude de la dynamique de la Terre interne, de la structure et l'évolution des planètes, de la dynamique naturelle de l'environnement et l'impact des activités humaines, de la modélisation, la prédiction et la gestion des catastrophes naturelles, tremblements de terre et éruptions volcaniques. Ces thèmes transverses sont présentés dans les pages de cette rubrique, sous l'angle de la recherche, de l'enseignement et en direction du grand public.
Earth's Deep Layers Study Guide Introduction The soil we step on when we take a stroll in the woods is only a thin layer, sitting on top of rock that goes down mile after mile after mile – indeed thousands of miles, What is inside the earth? At the earth's core, temperatures are estimated to be those at the surface of the sun. Earth's interior is like an onion: layers all the way down. Earth's Core and Magnetic Field When the earth formed approximately 4.5 billion years ago, the heat generated from all the impacts that formed it and heat from the high levels of radioactive elements in rock put the earth into a molten state. As the earth cooled over geological time, layers were permanently created based on the original sepa ration of types of materials. The core begins at 2,880 kilometers (1,800 miles) beneath Earth's surface. Furthermore, although the composition of the core is about the same throughout, its properties change dramatically at a depth of about 5,140 kilometers (3,190 miles) below Earth's surface.
What are the layers of the earth? Three hundred years ago the famous scientist Isaac Newton calculated, from his studies of planets and the force of gravity, that the average density of the Earth is twice that of surface rocks and therefore that the Earth's interior must be composed of much denser material. We now know that the earth is made up of 4 layers: How do we know about the different layers of the earth? Information today comes from studies of the paths and characteristics of seismic waves from earthquake waves traveling through the Earth, as well as from laboratory experiments on surface minerals and rocks at high pressure and temperature and studies of the Earth's motions in the Solar System, its gravity and magnetic fields, and the flow of heat from inside the Earth. About Seismic Waves What are the different types of Seismic Waves? Seismic waves are waves of energy that travel through the earth, for example as a result of an earthquake, explosion, or some other process that imparts low-frequency acoustic energy.
web.ics.purdue.edu/~braile/edumod/earthint/earthint.htm Educational Objective: Develop understanding of the structure of the Earth’s interior (and ultimately, relationships to plate tectonics, occurrence of earthquakes and volcanoes, and the origin of the Earth’s magnetic field, etc.) by constructing a scale model of a “slice” of the interior of the Earth and studying the material properties of Earth’s interior. The activity also provides useful practice with the concept of scale. Possible Preparatory Lessons/Activities: Density Elasticity and seismic waves Seismic waves and travel times in the Earth (evidence from seismic velocities for the existence of the core) Plate tectonics -- Lithosphere, asthenosphere Primary chemical layering of the Earth -- Crust, Mantle, Core Materials: two 11” x 17” sheets of paper taped together along the short side* meter stick pencil ~ 70 cm long string with loop at one end transparent tape colored pencils, crayons or felt pens (optional) Extensions: 1. 2. 3. 4. Related Materials: 1. 2. 3. 4. 5. References: U.S. Table 1.
Earth Science | Earth Structure The deepest places on Earth are in South Africa, where mining companies have excavated 3.5 km into Earth to extract gold. No one has seen deeper into Earth than the South African miners because the heat and pressure felt at these depths prevents humans from going much deeper. Yet Earth's radius is 6,370 km – how do we begin to know what is below the thin skin of the earth when we cannot see it? Evidence about Earth's interior Isaac Newton was one of the first scientists to theorize about the structure of Earth. Volcanic vents like Shiprock occasionally bring up pieces of Earth from as deep as 150 km, but these rocks are rare, and we have little hope of taking Jules Verne's Journey to the Center of the Earth. Earthquakes can be extremely destructive for humans, but they provide a wealth of information about Earth's interior. Seismic waves An earthquake occurs when rocks in a fault zone suddenly slip past each other, releasing stress that has built up over time. Enlarge The Moho Shadow zones
The Geological Society The surface of the Earth is the top of the 'crust' - whether one is under the sea or on land! By and large, the portions of the crust that poke above the sea to form land consist of 'continental crust'. If you were to drill into this, you would find rock with an overall composition similar to granite - a rock rich in the minerals feldspar and quartz (aluminium and silicon). Continental crust is thick - but after about 35 km of drilling, you would finally come to a different layer with a different chemical composition at a boundary called the Mohorovicic Discontinuity or Moho (named for the Croatian seismologist who discovered it). Chemical layering of the crust and upper mantle Image courtesy of Pete Loader. If you were to take a drillship and drill through the crust of the ocean floor, however, you would encounter a very different type of rock. Below the Moho, the mantle extends to the surface of the Earth's outer core - about 2890 km down.
Differentiation Demonstration: Moon Overview In this 15-minute demonstration or 30– to 45-minute activity, children, ages 8 to 13, observe a model of planetary differentiation, the organization of planetary interiors into layers of different densities. Materials of different densities are mixed in a bottle and allowed to separate into layers. The simple model illustrates how the Moon's interior became organized into a distinct core, mantle, and outer crust from the debris of the Giant Impact. What's the Point? Like Earth, the Moon's materials separated into distinct layers of different densities: a dense metallic core, a rocky mantle of intermediate density, and a rocky crust that is comprised of the least dense materials. Materials For the group, or for each group of 3 to 4 children: For the facilitator: *Select a straw color that is distinct from the gravel color. Preparation Prepare a Differentiation Demonstration bottle. Activity 1. Is the Moon — or Earth — composed of only one, or several different, layers? 2. 3. 4.
The Earth and the Moon What's covered here:What are the physical characteristics of the Earth's interior, surface and atmosphere? What are the physical characteristics of the Moon? Where did the Moon come from? Even though you might not think of it as such, the Earth is a planet. Here we're just going to treat it like one. However, the Earth is a very important planet, not because you live there, but because it provides us with a basis for comparison to the other terrestrial planets. What exactly do we know about the Earth? Geologists use the information obtained in earthquakes. First, we'll tackle the P-waves They are a form of pressure waves and are most similar to sound waves in how they travel (by pushing material) Pressure wave and Primary waves are other names for them. These move in a rather wiggly, transverse motion, sort of what you get if you take a rope and jerk it up and down quickly - a hump will travel down the length of the rope. Figure 1. Figure 2. Figure 3. Figure 4. The Crust - plate system
Astronaut for Hire: The Lunar Core As the self-professed "Astronaut Seismologist," I am very excited by yesterday's NASA announcement confirming that the Moon does indeed have a core. The news accompanies a report published in the journal Science by Weber et al. Having just read the paper and its extensive supplemental material, I will devote this post to conveying my initial impressions of the research. SPACE.com, Science Daily, Science, Discovery News, and Daily Mail had very public-friendly writeups on this story that are worth a look too. The gist of the paper is that the moon has a solid inner core, a liquid outer core, and a mushy partially molten region above the outer core. This finding is a big deal because by knowing the structure of the lunar core, we can understand the moon's present and past thermal state, the history of the lunar dynamo, and the origin and evolution of the Moon. Interestingly, this study found that the lunar core is only 40% solidified, meaning 60% of it is still in a liquid state.
Quick facts about the layers of the Earth | Lucky Sci In terms of volume and mass, the mantle is the biggest layer and the crust is the smallest. The crust takes 1% of earth's volume and 0.5% of earth's mass; the mantle commands 84% of earth's volume and 68% of earth's mass; finally, the core has 15% of earth's volume, but due to its great density, holds a disproportionate amount of earth's mass—31.5%. Scientists are able to "view" the interior of the earth by observing (with seismometers) seismic body waves that bounce back: S-waves and P-waves. The wave velocity changes with the density of the medium it is traveling through; an abrupt change in velocity helps mark a layer boundary. Additionally, since S-waves and P-waves travel at different speeds (see this animation), one can locate earthquake epicenters based on differential wave arrival times. S-waves are slower (in rock) and cannot travel through liquid (one clue that the outer core is liquid). Pressure and temperature are calculated based on mathematical relationships with depth.
Moon's Core Much Like Earth's — A new look at old Apollo seismic data confirms the structure of the moon's core. — Like Earth, the moon has a solid inner core and a liquid outer layer. The moon also has a mushy, semi-liquid layer around that. — A new NASA mission due to launch this year should provide more details of how the moon evolved. The moon may not only be a chip off the home planet. Using seismic analysis tools developed for probing Earth, scientists took another look at data collected by four sensors positioned on the lunar surface by NASA astronauts during the 1969-1972 Apollo moon program. The Apollo Passive Seismic Experiment recorded motions of the ground from moonquakes and other activities generating sound waves until late 1977. Those models turned out to be pretty accurate, says lead scientist Renee Weber, with NASA's Marshall Space Flight Center in Huntsville, Ala. The new research confirms the existence of a solid inner core and liquid outer layer, similar to Earth's.