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The Winter 2010 issue of The Earth Scientist includes a variety of educational resources, ranging from astronomy to glaciers. Check out the other publications and classroom materials in our online store.

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Movie courtesy of the Center for Space Environment Modeling (CSEM), University of Michigan.

# Model of a CME - Sun to Earth

This movie shows the results of a computer model of a coronal mass ejection (CME) as it travels from the Sun to Earth. Right-click (Windows) or Option-click (Mac) here to download a copy of this video in QuickTime format.

At the start of the movie, the Sun is represented by the small black circle near the left edge of the screen. Different colors (red through yellow, green, and blue) represent the density of subatomic particles of solar wind radiation. Red represents high density, while blue is low density. Values range from 100,000 particles per cubic centimeter (red) down to 1,000 particles per cubic cm. White lines represent magnetic field lines. The distance scales along the x- and y-axes are in units of solar radii (RS). At the start, the x-axis extends about 30 times the radius of the Sun to the right. The scale changes as the movie runs.

A coronal mass ejection (CME) blasts away from the Sun towards the right. It appears as an oval "bubble" of magnetic field lines. The CME moves away from the Sun and our view zooms out. A shock wave forms along the leading edge of the CME where the density of solar wind particles increases (shown in red). The CME reaches a distance of about 200 solar radii from the Sun. At this point, our view zooms in to show Earth (another black circle) surrounded by our planet's magnetic field (white lines). A multicolored wave representing the CME sweeps over Earth's magnetosphere, shifting and disrupting Earth's magnetic field.

The movie displays a grid of black lines around Earth to illustrate how the computer model works. The computer model repeatedly calculates the conditions (particle density, magnetic field strength, and so on) inside each square box (modellers call these boxes "cells") represented in the model. Note how the grid cells have different sizes. The cells are smallest near Earth, where it is especially important to scientists to see model results in detail. Further away from Earth, the grid cells are larger. Larger (and thus fewer) cells require less computer processing time to run the model. This is important, for complex models like this one can take days to run... even on very fast supercomputers.

Last modified January 27, 2010 by Randy Russell.

#### Shop Windows to the Universe Science Store!

Cool It! is the new card game from the Union of Concerned Scientists that teaches kids about the choices we have when it comes to climate change—and how policy and technology decisions made today will matter. Cool It! is available in our online store.

## Traveling Nitrogen Classroom Activity Kit

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

## The Magnetic Field

The force of magnetism causes material to point along the direction the magnetic force points. This property implies that the force of magnetism has a direction. As shown in the diagram to the left, the...more

## The Sun's Magnetic Field

The Sun has a very large and very complex magnetic field. The magnetic field at an average place on the Sun is around 1 Gauss, about twice as strong as the average field on the surface of Earth (around...more

## Particle Radiation

One main type of radiation, particle radiation, is the result of subatomic particles hurtling at tremendous speeds. Protons, cosmic rays, and alpha and beta particles are some of the most common types...more

## The Earth's Magnetosphere

The Earth has a magnetic field with north and south poles. The magnetic field of the Earth is enclosed in a region surrounding the Earth called the magnetosphere. As the Earth rotates, its hot core generates...more

## Modeling Space Weather

Scientists who study space weather make extensive use of computer models to make sense of complex phenomena. This is a way in which space weather is quite similar to Earthly weather, for weather forecasters...more

## Using Computers for Science

In the last decades, computers have become a normal part of life. They are used to send e-mail, write a school report or look up recipes. They are used to keep track of the balance in your bank account....more

## What is a Supercomputer?

Some scientific problems and processes are so complex that you need SUPERCOMPUTING power to tackle them! Just what is a supercomputer? A supercomputer is a computer that is among the largest, fastest or...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information.