An article posted by the American Optimetric Association
http://www.aoa.org/x5352.xmlIt is actually a reprint of a USAF report on night vision.
You will never match a cat for night vision, their rod cells are designed differently and they have a reflective layer behind them too. But if you do the 45 minute adaption cycle you might be surprised how good your night vision is.
Besides guarding your night vision there are a few other tricks about light at night.
A small light like a candle can be seen up to 20 miles away on a clear dark night.
Most towns produce a lot of light and it shows up as skyshine. If it is dark of the moon and overcast small towns can be located up to 40 miles away by their light reflected off the clouds. Possibly much farther if you are in flat country.
If the night is clear you might get some help from the stars.
The pole star is often hard to make out, but the Big Dipper is usually easy to recognize. If you think of it as a pointer to the pole star it can give you another rough guide to north.
If you know the constellation Orion you should know the stars of Orion's belt rise and set almost due east and west. This is because they are on the celestial equator and it is true all year long.
A trick used by astronomers when trying to see dim stars is to look slightly to the side of them. That puts the light from the star on the rod cells. If you look directly at a dim star it falls on the cone cells and disappears.
However the biggest light in the sky is the moon.
If you think about the moon being roughly on the ecliptic you will understand that you can get a rough indicator for north and south.
The sun lights the side of the moon that faces it and the division between day and night on the moon is north and south.
If it was at the equinox and at it would be accurate. It varies through the year because the earths axis is tilted 22 degrees and a bit to the plane of our orbit around the Sun. That is why it is an approximate north south guide.
It also gives you east and west as it rises and sets.
Don't forget your hearing. Sounds travel a surprising distance. The sound of a distant highway or running water might help you to orient yourself.
Walking at night is more like how you would walk when stalking.
Feel the ground with your foot before shifting your weight onto your foot. You might avoid stubbing your toes if you avoid swinging your foot as much as normal too.
Be careful moving through brushy areas. It is easy to get poked by branches or tripped. Guard your eyes. If you have safety glasses they might be good to have on.
Of course if you have access to night vision goggles a lot of this changes.