 |
Weekly Online LessonOnline Lesson ArchiveGrade Level: 7-10
|
Solar Storm
Space
Weather Forecasters from the National Oceanic and Atmospheric Administration
reported a strong coronal mass ejection, also known as a CME or a solar
flare, on the morning of Friday, June 13, 2000. Instruments onboard the
Solar and Heliographic Observatory (SOHO) captured images of the flare,
which lasted 40 minutes and peaked at 6:24 a.m. EDT.
Solar flares are eruptions of plasma and charged particles (gasses), some heading toward Earth at up to 3 million miles per hour. As the field deflects the incoming particles they get pushed toward earth's north and south poles where they appear as the northern and southern lights, called auroras. These beautiful streaks of colored light are often seen by people who live far north and south.
The
Earth’s magnetic field does a good job of protecting us from most of these
charged particles, but strong bursts can cause some disruptions. In 1989,
a severe solar storm knocked out power stations in Quebec and some northeastern
states. Since then, power grid and satellite operators have taken steps
to protect their systems.
Friday's intense solar activity is no real surprise to astronomers, who have known since 1843 that the sun goes through a regular cycle of low and high sunspot activity. The year 2000, it is believed, is the solar maximum for the current solar cycle.
This week's online lesson is about the sun, solar flares, and a colorful phenomenon known as an aurora.
Solar Views
The
sun is such an everyday part of our lives (literally) that we usually
don't even think about it. But the sun is the primary source of energy
and life on earth, and it is without a doubt the most prominent feature
in our solar system. For some good general information about the sun,
visit Solar
Views and go to the Sun
page. As you read the introduction, click on the diagram
of the sun in the third paragraph to see a larger view. Referring to this
diagram as you read will help you better understand new terms. How is
solar energy created? What are prominences? How will the life of the sun
end?
After the introduction you will find links to solar movies — short video clips on various sun topics ranging from solar eclipses to mass ejections. Click any one you want to view.
The Virtual Sun
You
can't visit the sun in person — you would fry — but you can take a virtual
tour of the sun by visiting The
Virtual Sun by Michiel Berger, which features a multimedia tour
of our closest star. Click Continue to flip to the next page of
the presentation. On some pages you will find links to movies and detailed
images. What is the difference between the photosphere and the
corona?
Solar Max 2000
Since
the year 2000 is the solar maximum (Solar Max — get it?) for the sun's
current activity cycle, visit Exploratorium's Solar
Max 2000 web site. Click What
is Solar Max to better understand the sun's solar cycle. You will
also learn how solar activity affects earth, and how solar winds disrupt
orbiting satellites. Also, check out the links under More on Solar
Max, including RealVideo descriptions of Solar Max.
Return now to the Solar Max 2000 home and look at the current solar images. Can you identify the corona and photosphere? Can you see an example of prominence in any of the images?
Paintings in the Sky
You
have learned that the sun occasionally erupts, that these eruptions blast
charged particles towards earth. The earth's magnetic field deflects most
of them, causing lights to appear in the sky near the poles. What do these
auroras look like from earth and space? Find out by visiting Exploratorium's
Auroras:
Paintings in the Sky. Read the introduction and take the Self
Guided Tour, which answers some of the most commonly asked questions
about auroras. Click each question to explore the answer. If you want
to hear an explanation of the answer, click the RealAudio link at the
bottom of each page.
Why are auroras different colors? What determines how "big" an auroral event will be?
© Copyright 2002
Learners Online, Inc.