We live in a world of light, almost anywhere in the United States you walk out the door in the middle of the night and you will see lights. They are everywhere and as a result; we fail to fully understand the question, how far away can you see a candle at night.
Because the earth is round, its surface curves out of sight at a distance of 3.1 miles, or 5 kilometers. Now with normal eyesight our visual acuity extends far beyond the horizon. If the Earth was flat, or if you were standing high on a mountain, you could see bright lights hundreds of miles in the distance. On a dark night, you could even see a candle flame flickering up to 30 mi. (48 km) away.
Because most of us live in areas where we are used to seeing lights all the time, we fail to realize how far away they can be seen. When you are bugging in and light that candle, you had better be sure that it cannot be seen from outside your home. See the following article for information on blacking out your windows. The Problems of Blacking Out Your Windows When Bugging In
Cigarettes or any other light sources can be seen from much farther than we are used too, 3.1 miles on flat land, farther if the observer is at a high elevation.. With all the ambient lights that surround us, most of us are not used to a truly dark night, many who live in a city may never have seen one.
When you are planning on how to light your bugging in locations or lighting that campfire, think about the question of, how far away can you see a candle at night. If you look at yourself as the center of a circle depending on the terrain, anyone 3.1 miles in any direction may be able to see your light. If the person looking is on high ground, he may be farther away.
Take a map of your area and draw a circle 3.1 miles in diameter with you at the center, now take terrain features and landscaping into consideration and you can determine from where lights at your location can be seen.