Slider images: 1  Attribution: RoyalTen73; License: public domain. 2  Attribution: Unknown; License: public domain. 3  Attribution: The Missionary Repository for Youth, and Sunday School Missionary Magazine; License: public domain. 4  Attribution: not given; License: public domain.
if you are driving with your high beam lights on you must dim them at least 500 ft from any oncoming vehicle so you don t blind the oncoming driver you must use low beam lights if you are within 200 300 ft of the vehicle you are following consult your state s drivers handbook for details if an approaching car is using its high beams don t look directly into the oncoming headlights look toward the right edge of your lane
Various claims in television commercials and on the web suggest that the human eye can detect a candle flame 3.5 to 30 miles away. These claims are wrong, in large part because the background light of the sky is not taken into account. Even at a dark sky site, the V-band sky brightness on a moonless night varies from 21.0 to 22.0 mag/sec2 (136 to 54 nL) over the course of the 11 year solar cycle. One calculation on the web sets the background to 0.1 nL, as if one had a photographic dark room miles in extent.