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06/14/2022

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MadRocketSci

Random note about your blog:
I can't seem to access it from my Samsung Internet browser on my phone, or from firefox on Windows sometimes. I get some DNS error. I'll check the details later, but it's bugged me before.

"I know of at least a couple of SF writers who have basically given up on creating their own alien star systems and just pick real ones."

One issue with that might be that, because most of our extrasolar planets are from the Kepler mission's transit method, we've only got some milli-arc-second field of view out into the galaxy where all these detected planets are at. Many of the closer stars to the sun are still unmapped.

Re: The sun being a "yellow star": I was actually working through a bunch of radiometry problems the other day to figure out sky radiance under various conditions. One reason that the sun appears yellow from below the atmosphere is the same reason the sky appears blue: Rayleigh scattering. That short-wavelength energy was stolen from the direct line of sight and smeared out over the whole sky. From space, the blue end of the spectrum is more energetic and the sun appears bluish-white.

You can look up an ISS photo with the sun in view: One is here: https://www.space.com/earth-perihelion-closest-sun-approach-2020.html

In general, hotter stars are "blue-er" than colder stars, but the color balance to the human eye is shifted by our atmosphere.

Aaron

MadRocketSci

The sun appears red at sunset because the slant path through the atmosphere is longer. Longer wavelengths are being scattered out of the direct path. Also the sky around the sun is greenish at sunset. (Atmospheric conditions wildly vary though.)

By my calculations, the mean free path at 700nm is something like 145.8km, at 550nm, 55.2km, at 450nm 22.7km.

On a clear day in the desert southwest, looking ~30 km or so to a mountain range, all the blue was washed out of the image, and the green was starting to blur. The fine details could only be perceived in the red.

MadRocketSci

Re: Details of my trouble accessing your blog:

It seems to be some google chrome thing. When entering variations of http://jamescambias.com or https://jamescambias.com, I get the following:

This site can’t be reached. Check if there is a typo in jamescambias.com.
DNS_PROBE_FINISHED_NXDOMAIN

I have to enter (specifically) https://www.jamescambias.com to reach the page.

Laz

Not the right post, but I found the other locked. I'm just reading Perelandra for the first time and noticed at the beginning of chapter 3 there is this connection to HP Lovecraft and specifically the colour out of space:

“I think he was
referring to some system of meditation which claimed to make ‘the
form of Life itself’ visible to the inner eye. At any rate Ransom let
himself in for a long cross-examination by failing to conceal the fact
that he attached some very definite idea to this. He even went so far
— under extreme pressure — as to say that life appeared to him, in
that condition, as a ‘coloured shape’. Asked ‘what colour?’, he gave
a curious look and could only say ‘what colours! yes, what colours!’
But then he spoiled it all by adding, ‘of course it wasn’t colour at all
really. I mean, not what we’d call colour,’ and shutting up complete-
ly for the rest of the evening."

In my view this is definitely paying homage to Lovecraft 🙂

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