The Magnetopause Boundary

Abstract

In this activity students explore in a quantitative way, how the distance to the bowshock balance point depends on the solar wind pressure acting on the Earth's magnetic field. They will explore the changes using actual satellite data, by both an algebraic and a graphical process. Students will discover that as the solar wind flows past the Earth, it applies pressure to the magnetic field of the earth, sweeping it back into a comet-like shape on the nighttime side of the planet and that the brunt of the solar wind pressure is exerted on the dayside field, compressing it; only the restorative pressure of the magnetic field pushes against the solar wind, and a rough balance of these pressures occurs. Students also learn that this balance moves towards the Earth when the solar wind pressure increases, and it moves outwards toward the sun as the solar wind pressure slackens. This line is called the magnetopause boundary. During this activity students use simple algebra to calculate the distance to the boundary where the solar wind presses on Earth's magnetosphere. Educational levels: High school