The Bortle Scale and Light Pollution

The Bortle Scale is used by astronomers to rate the darkness of our skies. It ranges from 1 (darkest) to 9 (brightest). For most of us, our daily lives are spent beneath a radiance level of between 5 and 8 and rarely venture into areas ranked 3 or darker- and what a shame that is.

Light pollution, while a testament to our technological advances, has blanketed our view of the universe and decoupled our relationship with the cosmos. For the millions of people living in areas where less than 20 stars can be seen in the night sky, it is practically impossible to imagine a natural sky blanketed with upwards of 2,500 stars backed by great ribbons of billions of stars which can be found in our Galaxy: The Milky Way.

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Your guide to the best meteor shower of the year: the Geminids

“The difference between a pristine, dark sky and an urban, light polluted sky is absolutely tremendous. The brightest, most infrequent meteors can still be seen from a badly polluted sky, but they’re not very spectacular. On the other hand, a very dark sky can result in you seeing ten times as many meteors, with the brighter meteors appearing much more spectacular! (If you’re wondering, a full Moon can turn a dark sky from a “1″ into an “8″ on the Bortle Dark-Sky Scale.)”

Every once in a while, the Earth hurtles through the orbital path of a comet or asteroid, with the Sun having torn tiny bits of debris from the parent body. As a result, the Earth strikes these dusty fragments at speeds often exceeding a hundred thousand miles-per-hour, resulting in a tremendous light show: meteor showers! Most people wind up disappointed in meteor showers for two reasons: they don’t know what to expect and they don’t know how to view them. So I’ve done my best to fix that, by explaining exactly where they come from, what the science behind them is and giving you tips and tricks for how to optimize your viewing experience.

Here’s to clear skies, good conditions and a year-end experience for the ages. Now, go enjoy the Geminids!

Light Pollution Simulation / Bortle Scale

Medical research on the effects of excessive light on the human body suggests that a variety of adverse health effects may be caused by light pollution or excessive light exposure, and some lighting design textbooks use human health as an explicit criterion for proper interior lighting. Health effects of over-illumination or improper spectral composition of light may include: increased headache incidence, worker fatigue, medically defined stress, decrease in sexual function and increase in anxiety.Light pollution poses a serious threat in particular to nocturnal wildlife, having negative impacts on plant and animal physiology. It can confuse animal navigation, alter competitive interactions, change predator-prey relations, and cause physiological harm. The rhythm of life is orchestrated by the natural diurnal patterns of light and dark, so disruption to these patterns impacts the ecological dynamics.Astronomy, both amateur and professional, is very sensitive to light pollution. The night sky viewed from a city bears no resemblance to what can be seen from dark skies. Skyglow (the scattering of light in the atmosphere) reduces the contrast between stars and galaxies and the sky itself, making it much harder to see fainter objects. (wiki)