Author Topic: SPOT  (Read 1671 times)


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« on: July 21, 2015, 04:32:25 am »

Im wondering how this mission determines the proximity to earth (ie. whether it will hit the earth / miss / glancing blow)?
Is the speed of the solar storm the only requirement?



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« Reply #1 on: July 21, 2015, 12:28:10 pm »
Both the speed and direction of the solar storm are needed to calculate any impact on Earth. The solar wind can also alter the CME speed - this is a quote from Chris Scott from the Solar Stormwatch science team:

There is some evidence that mass ejections interact with the backgrond solar wind so that if a storm is very fast it gets decelerated by the solar wind and slow storms get accelerated up to the solar wind speed. It takes some time to do this though. We've just published a paper showing that if you compare the speeds of a storm measured close to the sun in the STEREO coronagraphs with the speed of the same storm measured in the Heliospheric Imagers, you can see this effect.

As a rule of thumb a storm seen in "Spot" is likely to be Earth-bound if it looks roughly equal in both Ahead and Behind and appears at the 9 and 3 o'clock positions respectively.

However, the STEREO spacecraft are just coming out of solar conjunction and CME predictions have not been possible for several months. STEREO A is pretty much back to normal but STEREO B has been unresponsive since October 2014. You can follow progress via the Stereo Science Center.
« Last Edit: July 21, 2015, 03:11:25 pm by jules »