Observatory - Nighttime Viewing
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The observatory is now open to the public. Press
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 There
are many things you can do to prepare for your evening visit to the
Cameron Park Community Observatory that will make your visit even
more enjoyable. Dressing appropriately for the weather conditions is
the most important and that subject is covered extensively in the
web page entitled How to dress for
your evening of viewing.
The next most important thing to remember about nighttime viewing
through a telescope is the adaptation of your eyes to darkness. Have
you ever noticed that when you go outside at night it is difficult
to see and it seems very dark? Have you noticed also that after
twenty minutes or so you can see many more things in the darkness
around you and you can see millions more stars in the skies above?
Since most sky objects are quite dim as seen through a telescope or
binoculars, it is important to understand the conditions that permit
the best visibility There is a pigment called visual purple that
accumulates in your eyes. The amount of visual purple determines the
sensitivity of the eye to light, and reaches maximum in darkness
after about thirty minutes. If you go into the dark, more visual
purple accumulates in your eyes, enabling you to see better in the
dark. As you go into the light, or when light is shined into your
eyes, less visual purple accumulates in your eyes.
Knowing how your eyes respond to light and dark is very important
for you to have an enjoyable evening of viewing through a telescope
and will help you avoid situations that will cause your night vision
to become instantly ruined. For example, it will take your eyes 30
minutes or so to become completely adapted to the dark but just a
second or two for them to become re-adapted to daylight if you look
at a bright light. If you or someone else shines a flashlight into
your eyes, it will take 30 minutes again for your eyes to adapt to
the darkness. |
Here are our suggestions to help you adapt to the darkness at our
Observatory. When you first arrive, begin the process of adapting
your eyes for best night vision. After you park your car, try to
avoid looking at any lights, particularly other car headlights.
Bring a SMALL flashlight, like the pen lights circled in green in
the photograph at the right. Do not bring big bright flashlights to
the Observatory. As you start up the Observatory path you will
notice very dim path lighting, much like the path lighting in a
garden. This dim lighting is designed to allow you to see where you
are walking while allowing your eyes to adapt to the darkness. Walk
along the path nearest the lights. If you need more lighting to see
your way up the path, use your pen light to help. Be careful as you
walk up the path. If your eyes are not adapting to the darkness,
slow down or pause for awhile. The longer you are in the dark, the
better you will be able to see. If you think you need assistance
walking up the dimly lit path, ask for assistance from a guide in
the parking lot.
An even better flashlight to use is one designed for, or adapted
for telescope use. This type of flashlight will have a red lens or a
piece of red cellophane wrapped around the front. Red light does not
affect your night vision.
Another important technique to use when viewing objects in the
night skies is called "Averted Vision". This means looking
slightly to the right or left, above, or below an object instead of
directly at it. Your eyes are primarily designed to see in the
daylight and therefore focus most light in the center of the eye.
But cells away from the center of your eye are more adapted to
seeing dim objects.
Now, after all you have read above, can you tell us what is wrong
with the picture at the top of this web page? The answer is below
(read the sentence backwards).
Answer: .area viewing telescope the of out lighting bright all
keeping to contrary is This. lit brightly are child and mother The
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