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Blogs > loveisamyth > loveisamyth, stars are forever


loveisamyth 68M
849 posts
4/1/2015 7:43 am

Last Read:
4/2/2015 11:39 am
FORBUSH DECREASE
For the second time in two weeks, a Forbush Decrease is underway. In other words, the number of cosmic rays around Earth is down. Note the sudden drop in counts on April 1st in these data from the neutron monitor in Oulu, Finland.



Forbush decreases happen when CMEs sweep past Earth and push aside cosmic rays that normally surround our planet. A CME that hit Earth on March 17th, St. Patrick's Day, triggered the strongest geomagnetic storm of the current solar cycle. The corresponding Forbush Decrease lasted for days. The Forbush Decrease of April 1st probably won't be as deep or long-lasting. It was caused by a minor interplanetary shock wave that swept past Earth on March 31st; the shock wave's impact was weak and did not even spark a geomagnetic storm. Nevertheless, it did cause a reduction in cosmic rays.

To investigate the Forbush Decrease, later today the students of Earth to Sky Calculus will launch a "Space Weather Buoy" (suborbital helium balloon) with 4 radiation sensors to see if radiation levels in the stratosphere are tracking the ground-based neutron monitor counts. The balloon flight will also probe the effect of the Forbush Decrease at aviation altitudes.


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