Electromagnetism Electromagnetism

A Magnetic Light Show One of the most spectacular effects
caused by the Earth’s magnetic field is a curtain of light called
an aurora, like the one shown in Figure 12. An aurora is
formed when charged particles from the sun interact with
oxygen and nitrogen atoms in Earth’s atmosphere. When
charged particles from the sun strike these atoms, the atoms
emit light of different colors.
Earth’s magnetic field acts like a barrier to most charged
particles from the sun, so the particles cannot strike the atmosphere
in most places. But because Earth’s magnetic field bends
inward at the magnetic poles, the charged particles can crash
into the atmosphere at and near the poles. Therefore, auroras
are most often seen in areas near the north and south
magnetic poles. Auroras seen near the north magnetic pole
are called aurora borealis (ah ROHR uh BOHR ee AL is), the
northern lights, and auroras seen near the south magnetic
pole are called aurora australis (ah ROHR uh ah STRAY lis),
the southern lights.
REVIEW
1. Name the metals used to make ferromagnets.
2. How are temporary magnets different from permanent
magnets?
3. Applying Concepts Why are auroras more commonly
seen in places like Alaska and Australia than in places
like Florida and Mexico?
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Figure 12 The photo at left
shows what an aurora looks like
from the ground.
Science
CONNECTION
Auroras are a result of geomagnetic
storms. Read more about these
storms on page 478.
NSTA
TOPIC: Magnetism, Types of Magnets
GO TO: www.scilinks.org
sciLINKS NUMBER: HSTP430, HSTP435
Electromagnetism 461