night walking

As a teenager I was a fairly active amateur astronomer. One feature of the hobby for most of us is that the nights are frequently cloudy (most of us means people who don't live in the Southwest). I found one way to make use of the time was learn to walk with night adapted eyesight.

Nightwalking can be very beautiful. Very subtle things like glow worms (there were many of these at Stony Brook) and other luminescent objects from decay become prominent. You find yourself using your eyes in a way very different from its normal high illumination mode.

First some basics. The eye has photoreceptors called rods and cones -- cones are used for color vision and come in three flavors for most people. Rods are much more sensitive to light than cones (on average from 100 to 10,000 times as sensitive depending on the wavelength of incident light - average improvement, correcting for the number of receptors and receptor area is generally a few thousand times -- about what a good night vision scope achieves) and are not directly associated with color vision.

The trick is to find a very dark area and let your eyes become accustomed to it - generally about a half hour is required. I find averted vision best and, at least in my case, some areas of the eye seem more sensitive than others. Do some experimentation to learn what works best for you. I also find relaxing the gaze seems to help - don't try to consciously focus.

When you are fully adapted and relaxed you will find the eyes in a hunting mode ... in such conditions the eye is mechanically hunting for bright areas (the term for this is saccades and I tend to do it too much - when I take field of vision tests I find it very difficult to focus on a fixed target).

You want to make sure you are in a fairly smooth and/or well known area as you don't want to fall and injure yourself. I've found looking up at the sky can be an amazing experience if you try this on a very clear moonless night. Any moon on a clear night will be overpowering.

We generally talk about the amazing performance of animals - the wonderful eyesight of raptors and owls for example. But it turns out your own equipment is wonderful and with a few simple hacks you can explore capabilities that you probably didn't realize you had.

This is a fun result and science is driven by curiosity and play ..  but I also worry about energy and light is nothing but tiny particles of pure energy - photons.  We have an enormous fusion reactor that sits about five hundred light seconds away from us and fires a mind numbing number of photons every second to basically support all life and numerous physical processes on Earth.  Our little planet is covered by living photosynthetic biomass that is largely contained in a  layer ten meters about the ground and ten meters beneath the water.  It is inefficient, but life depends on it.

The energy that rains down on the Earth and that which has been stored will be the subject of many future posts.  Perhaps it will illuminate possibilities as well as limits and there is more than enough sunlight to power it.

 

Comments

[Brian]

Hi Steve,

I like the new blog, and these are great observations. For day creatures like us night is instant drama. It can tune us to a higher state, if only we let it. That owl certainly knows.

Brian