Do Reindeer See Quasars?

[bkm2304]

Hi all,

What Do Animals See In The Sky? (http://www.theamateurastronomer.com/blog) Given the incredible sensitivity to visual light and the ability to see in the ultraviolet and the infrared, animals must see an amazing sky above.

Richard

[JimsShed]

Well in the case of my dog, if he can't sniff it, then it doesn't exist :rofl:

[RB]

:lol: Jim.

:thumbsup:

[sopticals]

Really don't know how well some animals see in the dark. Many years back (1970s) I was a keen deer hunter (semi-pro meat hunter). Shot lots of deer at night (on deep dusk, and when pitch dark [using spotlight when in close-for the latter]). On one occasion, I remember well in what one would call, inky dark, I was able to stalk to within 6 feet of a wild deer grazing in an open field, without it being aware of my presence,(the same deer under reasonable light conditions would have fled at the sight of a human at 500m), so obviously didn't see my approach. Similarly was able to approach cattle, sheep without detection in the dark. Back then my own "night vision" was very acute, (still above average-when I see my peers stumbling over objects in the dark, which I can easily see).

[xelasnave]

I live in the bush with no light pollution or very little.
I have not experienced inky black.
I have imaged over 6 nights sleeping all day with little exposure to day light.
I find it easy to see on Moonless nights and can see well enough to get around.
I don't have any lights on when imaging or observing so get good adaption.
I can read large print without a Moon.
My conclusion is if seeing for me is so easy for animals it would be an easy matter.

[GeoffW1]

It's true,

I had a dog, he only used his eyes to keep from bumping his head on the power poles.

[bkm2304]

Some owl species possess 300 times the sensitivity of the human eye in dark conditions. If you use Pogson's ratio i.e. 5th root of 100, this sensitivity difference means whereas man sees celestial objects down to magnitude 6, owls see objects down to magnitude 15. Add to this the ability of many animals' eyes to allow UV light to reach the retina, and the ability of some to see to a limited extent in infrared, then you have a sky that is full of galaxies, quasars etc etc etc that we humans can only see with help. Human eyes are sensitive to UV but we don't get to see it because of the absorption properties of the tissues and substances between lens and retina.


Richard

[AussieTrooper]

It's entirely possible that some humans can see ultraviolet light after eye surgery. Monet is a classic example. After having cataracts removed, he went back and repainted some of the same scenes, which were now bluer than before.

Deer can be funny animals. I've spooked them 200m away sometimes, and at other times been able to get within 20m of them. If you sit perfectly still and are downwind, they can walk right past you. It may be that without motion they can't really tell what you are.
But one thing is for sure, they are damn tasty.

[rustigsmed]

a great subject! I had wondered how good my dog's night vision was, having a border collie I HAVE to take him to the park and play fetch in after returning from work... in the middle of winter that equals full night, most of the time he catches the ball after one bounce - where as I couldn't see it.

I found this article which has some good info on canine vision (strengths and weaknesses) for anyone interested - with some paragraphs posted below.

http://redwood.berkeley.edu/bruno/animal-eyes/dog-vision-miller-murphy.pdf

The canine visual system has adapted to exploit a
particular ecological niche by enhancing visual perform-
ance under low light conditions but still retaining good
function under a wide array of lighting conditions, including
daylight. Therefore, the dog's visual system is
not highly adapted for strictly diurnal or nocturnal conditions
but, rather, has evolved for an arrhythmic photic
existence.1'2 The minimum threshold of light for vision
in cats is approximately 6 times lower than that for normal
human beings.3 Although the minimum threshold
of light for vision in dogs is assumed to be somewhat
greater than that for cats, Pavlov concluded in the early
part of this century that the ability of dogs to analyze
the intensity of low-level illumination is so well developed
that human experimenters are unable to determine
its limits using their own senses.1

Dogs employ several methods of improving vision
in dim light. Both dogs and humans use rod photoreceptors
to function in dim light, but the central 25° of
the retina in dogs consists predominantly of rods.4 In
people, this region consists predominately of cones,
which are important for color vision and vision in bright
light. The rod photopigment, rhodopsin, is also slightly
different between dogs and humans. In dogs, rhodopsin
has a peak sensitivity to light of wavelengths between
506 and 510 nm and, as is typical of species adapted to
function well in dim light, takes over an hour to completely
regenerate after extensive exposure to bright
light.4

Rhodopsin in people, on the other hand, has a peak
sensitivity to light of somewhat shorter wavelengths (approx
496 nm) and regenerates more quickly after exposure
to bright light. The range of wavelengths to
which rhodopsin in dogs is sensitive4'6 suggests that the
visible spectrum for dogs in dim light is similar to that
of human beings, and that the enhanced night vision in
dogs, relative to humans, is not due to differences in the
range of wavelengths of light to which dogs and people
are sensitive.
The superiorly located reflective tapetum lucidum
also enhances the dog's ability to detect objects in dim
light. Presumably, it does so by reflecting light that has
already passed through the retina back through it a second
time, thus providing the photoreceptors at least 2
chances at capturing each quantum of light. This reflection
of light, however, has its price, as scattering of light
during this process may reduce the ability of the eye to
precisely resolve the details of an image.2

...

Summary
Compared with the visual system in human beings,
the canine visual system could be considered inferior in
such aspects as degree of binocular overlap, color perception,
accommodative range, and visual acuity. However,
in other aspects of vision, such as ability to
function in dim light, rapidity with which the retina can
respond to another image (flicker fusion), field of view,
ability to differentiate shades of gray, and, perhaps, ability
to detect motion, the canine visual system probably
surpasses the human visual system. This has made the
dog a more efficient predator in certain environmental
situations and permits it to exploit an ecological niche
inaccessible to humans