Starship Asterisk*

ems57fcva wrote:There is a problem here: The video is for New Horizons and not Fermi's gamma ray "rain".

I did find the Fermi video under the first link in the text. It is very interesting and worthy of being on APOD. I have the you get this APOD corrected quickly.

Perk Cartel wrote:Why is "Sol" ruled invalid by the securtiy question please?

The brightest persistent source in the gamma-ray sky is the Vela pulsar, which is about 1,000 light-years away. 3C 279 is millions of times farther off, but during this flare it became four times brighter than Vela.

Jim Leff wrote:We are frequently reminded that gamma ray bursts are among the most dangerous phenomena that can impact our planet. Yet in all the reports I've seen about 3C 279, including this one, no one's discussed any health impact. I understand this galaxy is way too far away for this to pose danger of any cataclysm, but, given that the purpose of this visualization is to impress us re: the strength of the burst, I can't help but wonder if some small background health effect (ie a handful of quiet, mostly dead-end mutations) may be involved.

videobear wrote:Why do the gammas appear to arrive in clumps? There seems to be about a half to 3/4 second pulsing in the arrival of the little buggers.

Chris Peterson wrote:

Jim Leff wrote:
We are frequently reminded that gamma ray bursts are among the most dangerous phenomena that can impact our planet. Yet in all the reports I've seen about 3C 279, including this one, no one's discussed any health impact. I understand this galaxy is way too far away for this to pose danger of any cataclysm, but, given that the purpose of this visualization is to impress us re: the strength of the burst, I can't help but wonder if some small background health effect (ie a handful of quiet, mostly dead-end mutations) may be involved.

There is no doubt that cosmic rays represent a source of mutations, impacting both evolution and individual diseases such as cancer. But the health impact of any one event like this is surely lost in the noise, indistinguishable from a million other tiny causative agents (like that coal burning plant in the next town, or the radon in your basement).

https://en.wikipedia.org/wiki/Blazar wrote:
<<A blazar is a very compact quasar (quasi-stellar radio source) associated with a presumed supermassive black hole at the center of an active, giant elliptical galaxy. Blazars emit a relativistic jet that is pointing in the general direction of the Earth. The jet's path corresponds with our line of sight, which accounts for the rapid variability and compact features of blazars.>>

https://en.wikipedia.org/wiki/Gamma-ray_burst wrote:
<<Gamma-ray bursts (GRBs) are believed to consist of a narrow beam of intense radiation released during a supernova or hypernova as a rapidly rotating, high-mass star collapses to form a neutron star, quark star, or black hole. All GRBs observed to date have occurred well outside the Milky Way galaxy and have been harmless to Earth. However, if a GRB were to occur within the Milky Way, and its emission were beamed straight towards Earth, the effects could be devastating for the planet. GRBs close enough to affect life in some way might occur once every five million years or so – around a thousand times since life on Earth began.

Depending on its distance from Earth, a GRB and its ultraviolet radiation could damage even the most radiation resistant organism known, the bacterium Deinococcus radiodurans. Life surviving an initial onslaught, including those located on the side of the earth facing away from the burst, would have to contend with the potentially lethal after-effect of the depletion of the atmosphere's protective ozone layer by the burst.

The greatest danger is believed to come from Wolf–Rayet stars, regarded by astronomers as likely GRB candidates. When such stars transition to supernovae, they may emit intense beams of gamma rays, and if Earth were to lie in the beam zone, devastating effects may occur. Gamma rays would not penetrate Earth's atmosphere to impact the surface directly, but they would chemically damage the stratosphere.

For example, if WR 104, at a distance of 8,000 light-years, were to hit Earth with a burst of 10 seconds duration, its gamma rays could deplete about 25 percent of the world's ozone layer. This would result in mass extinction, food chain depletion, and starvation. The side of Earth facing the GRB would receive potentially lethal radiation exposure, which can cause radiation sickness in the short term, and, in the long term, results in serious impacts to life due to ozone layer depletion.

Longer-term, gamma ray energy may cause chemical reactions involving oxygen and nitrogen molecules which may create nitrogen oxide then nitrogen dioxide gas, causing photochemical smog. The GRB may produce enough of the gas to cover the sky and darken it. Gas would prevent sunlight from reaching Earth's surface, producing a "cosmic winter" effect – a similar situation to an impact winter, but not caused by an impact. GRB-produced gas could also even further deplete the ozone layer.>>

Chris Peterson wrote:

Jim Leff wrote:We are frequently reminded that gamma ray bursts are among the most dangerous phenomena that can impact our planet. Yet in all the reports I've seen about 3C 279, including this one, no one's discussed any health impact. I understand this galaxy is way too far away for this to pose danger of any cataclysm, but, given that the purpose of this visualization is to impress us re: the strength of the burst, I can't help but wonder if some small background health effect (ie a handful of quiet, mostly dead-end mutations) may be involved.

There is no doubt that cosmic rays represent a source of mutations, impacting both evolution and individual diseases such as cancer. But the health impact of any one event like this is surely lost in the noise, indistinguishable from a million other tiny causative agents (like that coal burning plant in the next town, or the radon in your basement).

Ron-Astro Pharmacist wrote:We've come a long way in discovering the causes of most cancers in humans. Working in this field it surprises me that, considering the fear the disease evokes, we have the ability to limit, statistically, the most common causes but often don't avoid those exposures.

Chris Peterson wrote:

videobear wrote:Why do the gammas appear to arrive in clumps? There seems to be about a half to 3/4 second pulsing in the arrival of the little buggers.

Most likely the timing is described by a modulated Poisson distribution, which generally shows such clumping. It is statistically insignificant, but our brains are very adept at detecting such coincident events. Although the events are purely random, there is a finite probability of any two (or three, or four...) happening in any given interval. Our brain, being tuned for correlated events, overemphasizes the occasional clumps in comparison with the steady random background.

HomeAl0ne wrote:

Chris Peterson wrote:Most likely the timing is described by a modulated Poisson distribution, which generally shows such clumping. It is statistically insignificant, but our brains are very adept at detecting such coincident events. Although the events are purely random, there is a finite probability of any two (or three, or four...) happening in any given interval. Our brain, being tuned for correlated events, overemphasizes the occasional clumps in comparison with the steady random background.

It also seems to me that the events are spatially correlated. When you get a clump, there tends to be several in a straight line, and often the spacing seems regular. Is that an artifact of the detector? I seem to remember something about gamma-ray detectors using concentric metal tubes as lenses...

emc wrote:Maybe this helps with my argument that “Milky Way” is just too wimpy of a name. If I lived in 3C 279, I would scoff at such a puny preponderance. I would not be so quick to arms however if “Milky Way” were named... say, “Dragon’s Lair”... or “Death Trap To All Hostile Intergalactic Alien Invaders, Especially Those That Eat Meat”.