Solar Flares, CMEs, and Satellites,
Oh My!
M.M. Montgomery, PhD
University of Central Florida
LWS Heliophysics Summer School 2013
Summary of Lab/HW
In the lab, you analyze a Coronal Mass Ejection
(CME) that occurred on June 21, 2001. You
determine whether Earth is the path of the CME
and whether instruments on some space
observatories should be shut down. You run the
Community Coordinated Modeling Center (CCMC)
ENLIL software by NASA Goddard to check your
predictions and to compare with observations.
In the homework, you determine the likely energy
source to CMEs and solar flares.
Goals of This Mini Lecture
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What is the Scientific Method?
What are Solar Flares?
What are CMEs?
What is the solar wind?
What are Auroras?
What are Geomagnetic Storms?
What are Shocks?
The Scientific Method
“The process by which scientists form
hypotheses and test them against evidence
gathered by experiment or observation.”
Horizons Hybrid by Seeds, Backman, and Montgomery
LASP
Solar Flare
A solar flare occurs
when magnetic
energy, which has
built up in the sun’s
atmosphere, is
suddenly released
(i.e., think of a
sneeze).
A
two-ribbon
solar flare in Hα
(Heliophysics II,
Fig. 4.4).
Solar Dynamics Observatory (SDO)
image of the June 21, 2011 C7.7 class
flare (white, center). Image take in
extreme ultraviolet wavelength at 335 Å.
Credit: NASA/SDO
CME
A CME is a huge
bubble of gas that is
threaded with
magnetic field lines.
A CME is ejected
from the Sun over
the course of several
hours.
CME image using a
coronagraph on the
Solar
Maximum
Mission
satellite
(Heliophysics II, Fig.
6.1).
Image of the June 21, 2011 halo
CME using a coronograph on
the Solar and Heliospheric
Observatory satellite.
Credit: NASA/SOHO
Solar Wind
The sun’s hot gassy atmosphere containing
hydrogen, helium, and some heavier elements
expands into the solar system and flows past
Earth as shown below in the artist’s rendition.
Earth’s magnetic field deflects this wind.
Credit: Stereo.gsfc.nasa.gov
Aurora
Auroras are generated by
collisions between fast moving
electrons from space and
molecules in a planet’s
atmosphere.
In our own atmosphere, the
electrons give energy to
oxygen
and
nitrogen
molecules, exciting them, and
when they return to their
normal state, they release the
light we see.
Aurora on Saturn (top) and
at Jupiter’s pole (bottom).
Heliophysics I, Fig. 2.9
Aurora on Earth
Credit: GSFC.NASA.gov
Geomagnetic Storm
A rapid drop in Earth’s magnetic field strength at Earth’s
surface is a magnetic storm, which lasts 6-12 hours and
recovers over several days.
A CME carries the solar magnetic field with it, which
interacts with Earth’s oppositely oriented magnetic field.
Earth’s magnetic field is peeled open like an onion,
allowing the solar wind to stream down to Earth’s
magnetic poles.
Images from the IMAGE
satellite showing erosion of
Earth’s plasmasphere during
the Halloween storm of 28
October 2003. Heliophysics
II, Fig. 12.11.
Shocks
Shocks are generated in
areas when an object
moves faster than the
speed of sound. The
regions of the shock are
where gas properties
such
as
pressure,
temperature,
and
density increase by a
large amount almost
instantaneously.
Credit: NASA.gov
Cartoon of CME cavity, pileup shell, and shock front.
Heliophysics II, Fig. 6.2.
Questions to Ponder Before Starting
Homework and/or Lab
• How many types of energy sources can
you name?
• Can shocks be generated in a a) CME
and b) solar wind? If so, how?
• Can solar flares and CMEs damage
instruments on spacecraft? If so, how?
• Can auroras and geomagnetic storms
hurt you when they occur? If so, how?
Stereo A & B
Credit: NASA/JHUAPL
MESSENGER orbiting Mercury
Credit: NASA/JHUAPL/CIW