Solar Flares, CMEs, and Satellites, Oh My!

M.M. Montgomery, PhDUniversity of Central Florida

LWS Heliophysics Summer School 2013

Summary of Lab/HWIn 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

• 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). 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

A two-ribbon solar flare in Hα (Heliophysics II, Fig. 4.4).

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.

Image of the June 21, 2011 halo CME using a coronograph on the Solar and Heliospheric Observatory satellite.Credit: NASA/SOHO

CME image using a coronagraph on the Solar Maximum Mission satellite (Heliophysics II, Fig. 6.1).

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

AuroraAuroras 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 EarthCredit: GSFC.NASA.gov

Aurora on Saturn (top) and at Jupiter’s pole (bottom). Heliophysics I, Fig. 2.9

Geomagnetic StormA 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, pile-up 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 & BCredit: NASA/JHUAPL

MESSENGER orbiting MercuryCredit: NASA/JHUAPL/CIW