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View Full Version : How would one generate a starmap for non-human eyes?



swampyankee
2010-Jul-23, 03:32 PM
I can't think of a better place for this question, nor can I think of a much more bizarre question.

It's well known that different animals have different visual capabilities, e.g. bees can detect polarized light, cats have much better night vision, etc.

Is there any software which could use the spectral sensitivity of feline, or canine, or raptor eyes to generate the star map that one of those creatures could reasonably be expected to see?

George
2010-Jul-24, 08:39 PM
That's a neat idea!

I susppose the database would have to include the spectrum of every object up to some mag. limit for a wide range of wavelengths. Are we there yet with all the surveys?

The software should easily be able to adjust the "filters" to replicate the animals spectral response for each object. Then it is simply a matter of plotting the computed magnitude.

I'm guessing the code would be relatively easy to write, but the database size could get unruly. Of couse, if you only need a few thousand objects, maybe even the database size would not be too unruly.

astromark
2010-Jul-24, 09:00 PM
Entirely dependant apon the frequency being observed.. A radio telescope see's. For our understanding we can convert these images.

The visual part of the electro magnetic spectrum is a very small slice...Your question invites the thought. 'What if air was not clear.'?

Ultra sound. radar. What would mother nature have developed ? What would see mean ?

George
2010-Jul-25, 02:46 AM
The visual part of the electro magnetic spectrum is a very small slice...Your question invites the thought. 'What if air was not clear.'? That brings up an important point. If the spectrum's used are from space observatories then they must be adjusted for atmospheric extinctions, though this too wouldn't be all that hard since these are well known.

baric
2010-Jul-25, 04:37 AM
I think the challenging part would be understanding how animals see differently. Sharper vision or night vision doesn't really affect a star map. They would need to actually see into other parts of the light spectrum that slip through our atmosphere. That pretty much leaves the edges of the visible band that we cannot see well and the radio spectrum.

astromark
2010-Jul-25, 05:31 AM
Excuse me George... Could you word that differently please...? I do not understand ' atmospheric extinctions... Please.

I wonder if other species notice stars, Whales, dolphins Bats.... what do they see ? Do we know ?

Shaula
2010-Jul-25, 12:37 PM
Excuse me George... Could you word that differently please...? I do not understand ' atmospheric extinctions... Please.
Atmospheric transmission is wavelength dependent. Some areas of the spectrum are massively attenuated by the atmosphere (usually by CO2 and H2O but other species have an effect). Think George was saying that there would be no use making a red stamp if red light hardly propagated on an alien world.

George
2010-Jul-25, 03:32 PM
I think the challenging part would be understanding how animals see differently. Sharper vision or night vision doesn't really affect a star map. They would need to actually see into other parts of the light spectrum that slip through our atmosphere. That pretty much leaves the edges of the visible band that we cannot see well and the radio spectrum.
Yes. Some snakes, for instance, see well in the infrared end of the spectrum. Bats are a better extreme example, no doubt. On the other end of the spectrum, White-tail deer can see somewhat into the UV range and, with only two color cones, can not see into the red end at all.

George
2010-Jul-25, 03:50 PM
Excuse me George... Could you word that differently please...? I do not understand ' atmospheric extinctions... Please.
Sure. Sunlight must pass through our atmosphere before we, or the critters, see it. Thus, some of the light will be diminished. In fact, at sea level, almost 30% of the sunlight never reaches the surface. But this atmospheric reduction of sunlight is wavelength specific for a number of reasons. Attached shows how certain molecules can all but eliminate certain wavelengths from reaching the surface.

One important example is ozone, not shown, which does a great job of stopping harmful UV that the Sun sends our way.


I wonder if other species notice stars, Whales, dolphins Bats.... what do they see ? Do we know ? This is an interesting topic because we like to ask "why". Why do white tail deer see better in uv than we do? When I now climb into a deer blind just before sunrise, I now know that they can probably see me, which helps me justify why I only have shot one in over 40 years. :)

astromark
2010-Jul-25, 08:43 PM
Thanks to George and Shaula... thats good.

Roger E. Moore
2010-Jul-26, 02:15 PM
Bees apparently see far into the blue part of the spectrum, deep into the ultraviolet. An alien with eyes having that kind of sensitivity would use colors on printed material that we normally would be unable to see (except, perhaps, using special illumination and equipment). Bees probably see colors in flowers that we will never be able to detect or define, but they might also be unable to see shades of red that we easily detect. Imagine such an alien trying to read a human star map with planetary positions in the night sky marked in red, but being unable to see red.

Aliens who "see" by echolocation (e.g., bats, or Larry Niven's Kdatlyno from the Known Space series) would use star maps with embossed/raised/carved printing or scoring, with a Braille-like language they could "read" by echolocation or touch.

Also imagine aliens who have a type of color-blindness. They might use green and red interchangeably on their star maps, totally confusing humans who try to read them. I knew a colorblind woman who made boyfriends tell her if she was wearing mismatched colors, because she could not detect it. Some people are unable to see color at all, detecting only shades of gray with black and white. Aliens with this sort of vision would confuse many colors at once, but never know it.

Combine the above, and you might have a star map that has to be read by both sight and touch, but can only be understood properly when read under shortwave UV light to bring out the proper colors.

mugaliens
2010-Jul-27, 06:18 PM
This is an interesting topic because we like to ask "why". Why do white tail deer see better in uv than we do? When I now climb into a deer blind just before sunrise, I now know that they can probably see me, which helps me justify why I only have shot one in over 40 years. :)

They see motion far better than they distinguish shape/patterns. Many times I've walked up to deer by taking a step from downwind only when it lowers its head to pull grass. They definately hear me and take a look, but if I'm immobile, it just doesn't register.

George
2010-Jul-27, 06:53 PM
They see motion far better than they distinguish shape/patterns. Many times I've walked up to deer by taking a step from downwind only when it lowers its head to pull grass. They definately hear me and take a look, but if I'm immobile, it just doesn't register.Yes. That may be true with many or even most larger animals, though smell may be a more sensitive sense for some. It would be intersting to see a table of which animal's senses are the more responsive. I think I heard or read that men are more sensitive to movement than women.

Considering the OP, perhaps the movement of meteors is the only noticeable celestial object of interest besides the Sun and Moon.

mugaliens
2010-Jul-28, 01:46 AM
Considering the OP, perhaps the movement of meteors is the only noticeable celestial object of interest besides the Sun and Moon.

True, although we do like to "ask why." :)

swampyankee
2010-Jul-28, 02:27 AM
I know that dogs and cats have better night vision than do humans, so I suspect they may be able to see somewhat dimmer stars. They also have comparatively poor color vision, although they are not completely insensitive to color. Some vertebrates have 2 or 4, vs 3 (primate) color-sensing cells (cones); I believe some fish have more. Frogs pretty much can't see anything that's not moving. Insects see significantly farther into the UV, but some cannot see the color red. Insects also tend to have much poorer spatial resolution: it's not much better than 1 pel per ommatidium.

I guess the question is as biological as astronomical: determine the spectral sensitivity of the animal's eyes, and then adjust the spectra from a few thousand stars to account for the difference in sensitivity vs humans.

Has anybody actually tried this?

George
2010-Jul-28, 04:04 AM
I know that dogs and cats have better night vision than do humans, so I suspect they may be able to see somewhat dimmer stars. They also have comparatively poor color vision, although they are not completely insensitive to color. Some vertebrates have 2 or 4, vs 3 (primate) color-sensing cells (cones); I believe some fish have more. Frogs pretty much can't see anything that's not moving. Insects see significantly farther into the UV, but some cannot see the color red. Insects also tend to have much poorer spatial resolution: it's not much better than 1 pel per ommatidium.
A related question has been on my mind for quite a while... Would larger-eyed animals have greater ability to see in the dark, similar to telescope aperture but without the magnification gain effect?


I guess the question is as biological as astronomical: determine the spectral sensitivity of the animal's eyes, and then adjust the spectra from a few thousand stars to account for the difference in sensitivity vs humans. Yes, though air mass extinctions for altitude may be important, too.

Shaula
2010-Jul-28, 12:05 PM
Has anybody actually tried this?
I've done something analogous. Not for aliens but I have adjusted scenes to simulate how they'd appear in a range of sensors with different spectral responses and through different atmospheres. A cheap way to 'test' different systems against a particular task. E.g. can I use this sensor and these filters to image this nebula from this site. It is most accurate with simulated scenes as you don't need to deconvolve the imaging sensor's characteristics from the collected data first.

It is trivial to do a reasonable job, very complex to do accurately.

baric
2010-Jul-28, 03:59 PM
I guess the question is as biological as astronomical: determine the spectral sensitivity of the animal's eyes, and then adjust the spectra from a few thousand stars to account for the difference in sensitivity vs humans.

Has anybody actually tried this?

I'll take "I'd be shocked if that were true" for $500, Alex. :)

While there is certainly scientific interest in the spectral sensitivity of non-human eyes, I'd wager that none (zero, nada, nil) of it was motivated by the desire to determine how the stars looked when animals looked up in the sky at night. Too anthropomorphic.

Seems like the best approach would be to track down the sensitivity data and then perform the final step yourself. I'm guessing the starmap would only look much different for insects with UV sensitivity, though you'd then have to deal with their poor resolution.