written by: Eli Misel•edited by: Jason C. Chavis•updated: 7/23/2010
When you step outside on a clear night to view the sky it can take up to ninety minutes for your eyes to completely adjust to the darkness. If you need to reference star maps or other materials, using an astronomy flashlight can keep night sky viewing optimal.
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What is an Astronomy Flashlight?
If you have ever been to an observatory or star party, you may have noticed red flashlights being used. These are commonly referred to as astronomy flashlights. The use of red lighting during night time viewing has been utilized by astronomers for years. When viewing the night sky, the human eye gradually dilates over a period of up to ninety minutes. When the pupil is fully dilated, more light is able to enter the eye. This allows for optimal viewing of the night sky and deep space objects. If you need to reference star charts, notes or other materials while viewing the night sky, using a regular flashlight will cause the pupil to contract restricting the amount of light that enters the eye. When you look back up at the sky, your eyes will not be accommodated and will have to adjust to the darkness all over again. To mitigate this problem, astronomers started using astronomy flashlights. Astronomy flashlights are similar to regular flashlights, but use red lighting. The red light used in an astronomy flashlight provides a dull yet sufficient lighting to read star maps and materials without taking away from your sky viewing experience.
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How Much do Astronomy Flashlights Cost?
Astronomy flashlights can vary greatly in terms of cost depending on the size, type and quality of the flashlight being purchased. Most astronomy flashlights will use a series of red light emitting diodes which use less power resources and increase battery life. The use of light emitting diodes also provides a deeper red which is more pure than what a regular flashlight with lens filter can provide. Small flashlights can range from $4 to $10 dollars, while larger high quality flashlights can cost up to $50 dollars or more. Types ranging from key chains and pocket clips to heavy duty water proof models are available.
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Do it yourself Astronomy Flashlight
If you are on a tight budget or like to be resourceful, you can make your own astronomy flashlight with inexpensive materials. Red transparent tape used to repair damaged tail lights on automobiles can be purchased at many auto part stores for about $3 dollars. Using a regular flashlight, cover the flashlight lens with the red transparent tape. The red transparent tape acts as a lens filter creating a similar effect as a purchased astronomy flashlight. This can be a fun inexpensive way to owning your own astronomy flashlight.
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If you need to have light while viewing the night sky, using an astronomy flashlight will provide the perfect amount while keeping your eyes adjusted to the darkness. Whether you purchase an astronomy flashlight from a retailer or make your own from inexpensive materials, having an astronomy flashlight in your night sky viewing toolkit is a must have for any astronomer.