PDA

View Full Version : New Risk from Supernovas



NEOWatcher
2008-Jan-08, 07:44 PM
Long-term exposure to blue-enhanced light would interfere with life (http://www.msnbc.msn.com/id/22556771/)
Well, it took me a while to get past all the known data and the doom and gloom, then the "no not really bad" to get to the story.

Those who study chronobiology, or the effects of biological timing, have found that low levels of blue light can strongly affect the endocrine systems of mammals by causing physiological and alerting responses. Blue-enhanced light is associated with reduced levels of melatonin production and affects circadian rhythms. For these reasons, it is sometimes prescribed (http://www.livescience.com/health/060201_blue_light.html) to counteract seasonal affective disorder (SAD) or winter depression.

And Insomnia... We're doomed.

01101001
2008-Jan-08, 08:45 PM
We're doomed.

BluBlocker (http://www.blublocker.com/)TM sunglasses! As seen on TV!!

tdvance
2008-Jan-08, 08:49 PM
Gee--given the bluishness of old television tube light, why have so many fallen asleep in front of the TV?

Noclevername
2008-Jan-08, 09:14 PM
The article says this blue glow would last about half a year. Not much at all. And would only effect a tiny fraction of the world's population. So it's a minor issue, even assuming EC goes haywire anytime soon.

EDIT: (And for the record, the title really should be "Newly Recognized Risk from Supernovas".)

George
2008-Jan-08, 09:28 PM
There are a number of things about this that may be overkill. Consider these...

The peak radiation output of the Sun is in the blue, 485nm IIRC.

Our atmosphere will knock out about 20% or more of the blue when it is overhead (added: ~45% reduction at ~45 deg. elevation). Except for violets, the blues will be the weakest when the sn is near the horizon.

If it is bright enough, it will not appear blue. Once our color cones are maxed-out, all is white. The Sun could be blue, or yellow, and an astronaut would never know since, in space, the Solar flux exceeds greatly the eye's color cones threshold. [Of course, that is only when we foolishly stare at it, admittedly. :)]

Not speaking for other heliochromologists, the Sun is not blue or white. I know because I stay up late at night involved with this blue-background forum. :eek:

Celestial Mechanic
2008-Jan-08, 09:53 PM
Canadian lab rats sickened by exposure to supernovae, successfully treated with cyclamates! Film at 11!

Jens
2008-Jan-09, 08:29 AM
Long-term exposure to blue-enhanced light would interfere with life


The article only mentions "mammal" "endocrine systems." I hear there is a reptile and fish demonstration against this "classist" insinuation that life is equivalent to mammalian life!

trinitree88
2008-Jan-09, 03:54 PM
There are a number of things about this that may be overkill. Consider these...

The peak radiation output of the Sun is in the blue, 485nm IIRC.

Our atmosphere will knock out about 20% or more of the blue when it is overhead (added: ~45% reduction at ~45 deg. elevation). Except for violets, the blues will be the weakest when the sn is near the horizon.

If it is bright enough, it will not appear blue. Once our color cones are maxed-out, all is white. The Sun could be blue, or yellow, and an astronaut would never know since, in space, the Solar flux exceeds greatly the eye's color cones threshold. [Of course, that is only when we foolishly stare at it, admittedly. :)]

Not speaking for other heliochromologists, the Sun is not blue or white. I know because I stay up late at night involved with this blue-background forum. :eek:

George. This site says yellow-green for peak output. see:http://209.85.173.104/search?q=cache:tEfCgRqFeIAJ:soconnell.web.wesleyan .edu/wescourses/2004s/ees199/01/powerpoint/afterSpBreak/1-AtmosphereStructureAndGreenhouse.ppt+peak+radiatio n+output+of+the+sun&hl=en&ct=clnk&cd=7&gl=us

George
2008-Jan-09, 04:51 PM
George. This site says yellow-green for peak output. see:http://209.85.173.104/search?q=cache:tEfCgRqFeIAJ:soconnell.web.wesleyan .edu/wescourses/2004s/ees199/01/powerpoint/afterSpBreak/1-AtmosphereStructureAndGreenhouse.ppt+peak+radiatio n+output+of+the+sun&hl=en&ct=clnk&cd=7&gl=us
They are clearly in error. They discuss Wiens displacement but don't bother to apply it accurately. If they did they would get a peak Planck wavelenth of 0.483 microns (blue) [using their own temp. value of 6,000K]. They rounded off and simply stated 0.5 microns. Yet, even if we allow for approximation, 0.5 micron is not near yellow-green. It is light blue (cyan).

The actual peak as seen in space (AM0), using the Wiehrli '85 data set, is 450nm (0.45 micron). This is blue-violet. However, the energy level is relatively high from 445nm to 500nm (blue to cyan).

In fairness, in terms of photon flux (how the eye sees color) the peak is in the yellow, though not yellow-green. But this is not a peak. It's a pimple! :) The photon flux distribution is flat as a pancake, maybe with a little slightly raised pecan varriance. The blue region, surprisingly, is not near as flat as the rest of the visible spectrun due to the linear E=hf reduction.

The Sun is white. The central zone of the Sun is very likely white only. The limb is definetly white, though it is 1400K cooler than the 6400K central zone.