Solar Storms and You!
Activity 4: Coronal Mass Ejection Plotting Activity
Coronal Mass Ejection's are major storms on the Sun which can hurl billions
of tons of matter into space in a matter of a few hours. Traveling at millions
of miles per hour, some of these clouds occasionally collide with the Earth
and have produced power black outs and satellite damage. CMEs can start
out with a size of only a few 100,000 kilometers, but fan out to millions
of kilometers by the time they reach the Earth's orbit. Only CME's that
emerge from near the Sun's eastern limb stand a chance of traveling all
the way to Earth, so this is where astronomers look for early signs that
one is on the way!
Students will construct a table of values and plot the points in order
to make a prediction.
Student page and Teacher Answer
Plot CME 1 points from the appropriate tables and draw to scale
the thickness of the CME indicated in the 'Width' column of the table.
Plot CME 2 points from the appropriate tables and draw to scale
the thickness of the CME indicated in the 'Width' column.
By hand, sketch the path of the CME that hits the Earth and complete
the shape of the CME using the width information from the table.
Identify the location on the Sun where the sketched CME in procedure
#3 will emerge so that it hits the Earth. This point is about halfway between
the center of the Sun and the left (eastern) edge.
Show that most CMEs do not hit the Earth by choosing other CME
locations on the Sun and plotting the possible shape.
The points in the table were calculated for an assumed CME speed
of over 450 kilometers per second, however some CMEs can travel at a speed
twice this fast. Challenge your students to re-calculate the table entries
for a faster speed and redo steps 1-4 in this procedure. The students should
see the shapes of the CME trajectories become flatter. The point where
the CME that hits the Earth is ejected from the Sun will shift closer to
the left (eastern) edge of the Sun.
CME: A coronal mass ejection is a sudden ejection of mass from
the outer layers of the Sun. They travel at speeds of up to 1000 kilometers
per second and are millions of miles wide by the time they reach the orbit
of the Earth.
Coronal Mass Ejections don't all hit the earth, but the process requires just
the right set-up. Typically, if you can see the CME being ejected near the
limb of the sun, it will probably not affect the earth. The most likely
eruptions that can affect us come from regions on the eastern half of the
solar disk, provided they have the right speeds. CME speeds can vary from 400
kilometers/sec to over 1,500 kilometers/sec which means the arrival times and
favorable launch points on the disk can vary quite a bit.
Related Web Resources
Visit the IMAGE/POETRY
Page which has suggestions on how to study CMEs and their geomagnetic
effects in more detail. This page gives information appropriate to a science
fair project, or class project.
Return to the Table of Contents
This activity was developed by the NASA, IMAGE/POETRY
Teacher and Student Consortium.
For more information, and a list of other resources, visit