Trajectory of Coronal Mass Ejecta
Date: Fall 2013
How is the trajectory of a Coronal Mass Ejection plotted? How can one calculate (or get the information) of an intersection between the coronal mass ejecta and Earth?
There's an interesting article published by the Jet Propulsion Laboratory which details the process of in which NASA's STEREO Spacecrafts record images of the CMEs.
Image processing software reconstructs single points of the CME "loops" which tracks the position and velocity of the single point on the leading edge of the CME. This leading edge is determined by recording the "slope" of the CME loop at every reconstructed data point.
Once a single point is observed, it's longitude and latitude position is recorded and therefore it's distance traveled per unit time is determined and as a result it's average velocity is estimated by kinematics:
v = (r2-r1)/(t2-t1)
All sources of information above is referenced from the JPL Report:
"Determination of the 3D Trajectory and Velocity of Coronal Mass Ejections using Stereoscopy".
Thanks for the question. To determine the trajectory of a Coronal Mass Ejection, one needs to solve the dynamics equations from classical mechanics. Specifically, one solves the differential equation that results from Newton's Second Law (F = ma). The differential equation includes the varying effects of gravity (which is not constant over the length scale involved as well as electrical forces. With these complicating features, one solves the system of equations numerically subject to some initial conditions--such as how fast and where the Coronal Mass Ejection was detected. From the solution of the differential equation, one can easily determine the time and location of intersection of the Coronal Mass Ejection with Earth.
I hope this helps. Please let me know if you have more questions.
A place to start is NASA"s Space Weather site. They will send you e-mails which, amongst other significant events, include significant solar activities including, CME's that will affect earth (usually causing increased possibilities of aurora).
Hope this helps.
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Update: December 2011