Theory of Distance and Visual Limits

Early on in my astronomy career, I was looking at a rather nice astronomy book and it had wonderful high quality large photo prints.  They were obviously at the Hubble level, and they showed an excellent amount of detail.

I had left the book on my bed propped up, and upon my return, I noticed something.  I stood back a few feet, and noticed that there was less detail than being up close to it.  It seems like a rather oridinary thing, but I studied this for a while, and I started to formulate a scientific theory.

This theory states that there is a limit at which the human eye can detect color, and this varies to the person.  Plain and simple, at a certain distance, you can no longer detect color in an object.  I believe that this is possible in not just photographs, but as well live objects.

Step 1: Acquire a large, visual, preferably not very filtered astronomical picture.  The Orion Nebula and Andromeda galaxy are perfect.  Prop them up on a chair outside.

Step 2: Walk up to the photograph, and note the definite color and detail in the deep sky object.  Note and remember what you see.

Step 3:  Now walk back 10 feet, and study the photograph.  It now appears smaller, and with less striking colors and details.  What were beautifully detailed and cloudy objects are reduced to a smoother, mottled appearence.Note and remember what you see.

Step 4: Walk back another 10-15 feet and study the picture now.  It has most of it’s defined detail gone.  Now, when I got to this point, I came upon a problem.  Galaxies and nebulae emit their own light, and a photograph does not.  The solution I found was to have the picture be printed on a translucent piece of bendable plastic.  Now take a light, and shine it through the back, but scatter the light with a thin fabric sheet to make the light distribution equal over all diameters.  I probabily should have told you this before, so my apologies.

Step 5:  Now walk back again and again, repeating the process until which there is no more color detected by your eye.  This distance varies for everyone and generally, the view will be very similar to the view through a telescope.  You have now found your visual limit; but now what?

I am no math wizard, so there must be some kind of number system for the visual limit.  And if so, the object, distance of that object for real and the exposure time must also be accounted for.  This requires one big equation that I am definitely not up for.


This experiment actually works too! I tried it and there is something to this, try it yourself, it should only take a few minutes.  If you can’t have it printed on translucent plastic, another possible method is to print it out on regular paper or a poster and tape the paper to the plastic.  A decent astronomy poster that is somewhat large can be had for under 10 dollars on amazon.

Good luck and clear skies.