PDA

View Full Version : Earth as a Source of Gamma Rays



wstevenbrown
2004-Nov-27, 05:28 PM
I don't know if this is the right category, but trust the mods to sort it correctly. Both astronomical satellites and spy satellites (ok, nuclear test-ban monitors) have been plagued by an assortment of bogus returns-- gamma ray bursts that do not originate in space, and have nothing to do with nuclear detonations. Here is a partial list of returns from a Yahoo search (sprite + gamma + ray):

http://www.batse.com/

http://science.nasa.gov/newhome/headlines/...sd26may99_1.htm (http://science.nasa.gov/newhome/headlines/essd26may99_1.htm)

http://f64.nsstc.nasa.gov/batse/tgf/

http://www.innerx.net/personal/tsmith/GRB.html

http://www.uh.edu/research/spg/Sprites99.html

It seems that mild gamma ray bursts are a natural function of Earth's weather. The underlying causal mechanism, tho, is under debate. Have fun! Steve

antoniseb
2004-Nov-27, 05:47 PM
Originally posted by wstevenbrown@Nov 27 2004, 05:28 PM
gamma ray bursts that do not originate in space, and have nothing to do with nuclear detonations.
I haven't looked through these web-sites for this, but I would not be surprised to find that these terrestrial GRBs are spray from the 10^19 eV cosmic rays hitting the upper atmosphere. It seems increadibly unlikey that any gamma rays could have made it to BATSE from the level of thunderheads in the troposphere.

VanderL
2004-Nov-27, 06:54 PM
Earth as a Source of Gamma Rays, Sprites, Elves, Blue Jets

Well, I'm sure you can guess what I think is the cause of all these phenomena, maybe we should move this to the EU thread? :D


Cheers.

antoniseb
2004-Nov-27, 07:24 PM
You can bring up the topic in the EU thread, but there seem to be plenty of non-EU things to say about it here.

Duane
2004-Nov-27, 08:16 PM
These things are very cool! Pilots reported seeing these things for years, but they were basically pooh-poohed. I don't think the sprites etc have anything to do with gamma rays, although admittedly I am not well versed on the subject. I do know that gamma rays are relatively common and, like antoniseb says, arise from cosmic ray strikes in the upper atmoshere.

Now that they are under active study, it will be interesting to see how they are explained. I suspect it won't be anything otherworldly.

I seem to recall seeing something about sprites in Jupiter's atmosphere. Anyone know anything about that?

wstevenbrown
2004-Nov-28, 12:38 AM
"In addition to sprites and jets, but possibly related, there have recently been observed from space two other types of unexpected emissions that appear to originate in thunderstorms. Short duration (~1 ms) gamma ray (>1 MeV) bursts of terrestrial origin have been detected by the Compton Gamma Ray Observatory They are observed to occur over thunderstorm regions, and their source is believed to lie at altitudes greater than 30 km. Finally, extremely intense pairs of VHF pulses (Trans-Ionospheric Pulse Pairs, or TIPPS (TIPP Paper Postscript Source ) originating from thunderstorm regions, but some 10,000 times stronger than sferics produced by normal lightning activity, have been observed by the ALEXIS satellite."

I do want to stress that, as in the above quote from the University of Alaska site, nobody is yet willing to go out on a limb and say what the chain of causation is. As yet, thunderstorms are associated with sprites, blue jets, gamma ray pulses, and maser-like TIPPS, but as to who is causing what... As they say, a fertile field of inquiry. The gammas, though, originate within the storms and propagate upward-- they are not part of the usual downward debris fan of ordinary cosmic rays.
As an afterthought, it would be interesting if cosmics were the triggering events for arcovers exactly analogous to what goes on in a (you should pardon the expression) cloud chamber , summat scaled up! Enjoy--S

Duane
2004-Nov-28, 11:43 AM
Thanks Steven for that insight. This is a very interesting phenomina, I'm looking forward to some papers on them.