Author Topic: Episode 32: Sailors take warning  (Read 3470 times)

Offline bn

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Episode 32: Sailors take warning
« on: May 07, 2013, 06:46:17 PM »
Red Sky at Morning,
Sailor's take warning.
Red sky at night,
Rapper's delight.

Blue sky at morning,
things are just norming.
blue sky at night,
check your watch.

Today we talk to a 10 year old kid about why the sky is blue.

I wanted to tell all sorts of people about this topic, but no one wanted to listen because everyone thinks that they know the answer. EVERYONE IS WRONG. except me... kalamari. there's a contradiction in that statement.
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Offline darkfizzikcowboy

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Re: Episode 32: Sailors take warning
« Reply #1 on: May 09, 2013, 05:23:37 PM »
Just finished listening to the show and it was awesome! You and Dr. Bauer took a subject and got a 10 year old totally stoked about science.
Great job!
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Offline bn

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Re: Episode 32: Sailors take warning
« Reply #2 on: May 10, 2013, 11:38:51 AM »
his dad said he had trouble sleeping afterwards because he was so excited *brag*
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Offline scikopas

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Re: Episode 32: Sailors take warning
« Reply #3 on: June 06, 2013, 09:51:22 AM »
WAIT! I have questions.

Dr. Bauer mentions that we don't see any green stars because our eyes aren't as sensitive to green light, but from what I remember from learning about laser stuff I thought the human eye was MOST sensitive to 550nm green light... (http://www.light-measurement.com/spectral-sensitivity-of-eye/)  is there something I'm missing here about the relative sensitivities?

-OR-  I've heard two (unconfirmed by actual space/atmosphere/light physics type people) other explanations for why we don't see green stars:
  • the atmosphere (specifically water) has a huge absorption peak starting at 500nm, so absorbed green light will be re-emitted isotrpically and we only see the tiny contribution from the solid angle of our eyes (but water ALSO absorbs red!) (http://irina.eas.gatech.edu/EAS8803_Fall2009/Lec6.pdf fig 6.2, page 4)
  • even if the star's black body emission spectrum peaks in the "green" region there are "more wavelengths" that our eyes see as red, so the total sum of red vs green wavelengths still makes it look red-ish (even our sun peaks in the blue region)


I don't know anything about this stuff!!! am I completely wrong? is it some combination of all of those? help!


edit: added atmospheric absorption spectra source.
« Last Edit: June 06, 2013, 10:14:57 AM by aliencam »
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Offline bobmath

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Re: Episode 32: Sailors take warning
« Reply #4 on: June 06, 2013, 03:51:40 PM »
The sun has a spectral temperature of about 5500K, which puts the peak at 2.90e6/5500=527 nm (Wien's displacement law), which is right in the minimum between the two peaks in your sensitivity plot. See http://en.wikipedia.org/wiki/File:Solar_Spectrum.png

The spectra on page 4 don't show visible light. The ones on page 5 do, but I don't see any gaps around 0.5 micrometers.

The "more wavelengths" explanation is basically saying the same thing as the podcast.

Offline bn

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Re: Episode 32: Sailors take warning
« Reply #5 on: June 06, 2013, 05:55:07 PM »
but from what I remember from learning about laser stuff I thought the human eye was MOST sensitive to 550nm green light... (http://www.light-measurement.com/spectral-sensitivity-of-eye/

yeah!
i brought this up in the recording, and then deleted my complaints because they were half-remembered. I'll ask amanda to take a look at your question.
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Offline bobmath

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Re: Episode 32: Sailors take warning
« Reply #6 on: June 06, 2013, 07:52:35 PM »
Yeah, I think the peak's too broad and the valley's too narrow for that theory to work.