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Though astronomers need naturally dark skies to see and learn about faint and distant objects in the Universe, dark skies are valuable for everyone – they have been a source of beauty and inspiration to all of Humankind for as long as people have been aware enough to raise their eyes from the ground and wonder. And light that provides visibility without waste or glare is vital for vision for everyone. Concerns have also remained regarding the inverse of proliferating nighttime lighting, namely the rapidly declining access to a natural night sky in the developed world. In recent decades attempts to quantify skyglow and its global presence have emerged, however, data is still somewhat sparse. The first attempt to map this phenomenon on a global scale was published by Cinzano et al. (2001 Cinzano, P., Falchi, F., & Elvidge, C. D. (2001). The first world Atlas of the artificial night sky brightness. Monthly Notices of the Royal Astronomical Society, 328, 689–707.10.1046/j.1365-8711.2001.04882.x[Crossref], [Web of Science ®] [Google Scholar]). A more recent study by Gallaway et al. (2010 Gallaway, T., Olsen, R., & Mitchell, D. (2010). The economics of global light pollution. Ecological Economics, 69, 658–665.10.1016/j.ecolecon.2009.10.003[Crossref], [Web of Science ®] [Google Scholar]) built on their findings and concluded that the amount of people living in areas with a ‘polluted night sky’ is extremely high: around 99% in both North America and the European Union.88. Gallaway et al. (2010 Gallaway, T., Olsen, R., & Mitchell, D. (2010). The economics of global light pollution. Ecological Economics, 69, 658–665.10.1016/j.ecolecon.2009.10.003[Crossref], [Web of Science ®] [Google Scholar]) utilize the threshold criteria established by Cinzano et al. (2001 Cinzano, P., Falchi, F., & Elvidge, C. D. (2001). The first world Atlas of the artificial night sky brightness. Monthly Notices of the Royal Astronomical Society, 328, 689–707.10.1046/j.1365-8711.2001.04882.x[Crossref], [Web of Science ®] [Google Scholar]) for considering an area ‘polluted’ by light. These criteria ‘consider the night sky polluted when the artificial brightness of the sky is greater than 10% of the natural sky brightness above 45° of elevation’ (Gallaway et al., 2010 Gallaway, T., Olsen, R., & Mitchell, D. (2010). The economics of global light pollution. Ecological Economics, 69, 658–665.10.1016/j.ecolecon.2009.10.003[Crossref], [Web of Science ®] [Google Scholar], p. 660).View all notes Furthermore, on both continents approximately 70% of the population lives in areas where brightness at night is at least three times natural levels. From a dark rural area, our unaided eyes can normally see up to 3,000 stars; people with strong eyesight can even see close to 7,000 stars. However, in many urban areas today this number is reduced to around 50, or perhaps even less (Mizon, 2012 Mizon, B. (2012). Light pollution: Responses and remedies (2nd ed.). New York, NY: Springer.10.1007/978-1-4614-3822-9[Crossref] [Google Scholar]). Researchers caution that if the current pace of increasing brightness continues, the ‘pristine night sky’ could become ‘extinct’ in the continental United States by 2025 (Fischer, 2011 Fischer, A. (2011). Starry night. Places Journal. Retrieved 22 October, 2014,. from https://placesjournal.org/article/starry-night/[Crossref] [Google Scholar]). About 1.7 billion people or more than a fifth of the world’s population are without access to electricity and modern lighting. The problem is most severe in rural areas or on the fringes of cities. , however the extent to rural electrification varies widely from country to country.  For example, 90% of Africa is not served by grid electricity versus 20% of Mexico. In fact, some African countries, for example, Rwanda and Burundi have barely passed the 1% electrification threshold! Astronomy is very sensitive to light pollution. The night sky viewed from a city bears no resemblance to what can be seen from dark skies.[78] 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. This is one factor that has caused newer telescopes to be built in increasingly remote areas. Some astronomers use narrow-band “nebula filters” which only allow specific wavelengths of light commonly seen in nebulae, or broad-band “light pollution filters” which are designed to reduce (but not eliminate) the effects of light pollution by filtering out spectral lines commonly emitted by sodium- and mercury-vapor lamps, thus enhancing contrast and improving the view of dim objects such as galaxies and nebulae.[79] Unfortunately these light pollution reduction (LPR) filters are not a cure for light pollution. LPR filters reduce the brightness of the object under study and this limits the use of higher magnifications. LPR filters work by blocking light of certain wavelengths, which alters the color of the object, often creating a pronounced green cast. Furthermore, LPR filters only work on certain object types (mainly emission nebulae) and are of little use on galaxies and stars. No filter can match the effectiveness of a dark sky for visual or photographic purposes. Due to their low surface brightness, the visibility of diffuse sky objects such as nebulae and galaxies is affected by light pollution more than are stars. Most such objects are rendered invisible in heavily light polluted skies around major cities. A simple method for estimating the darkness of a location is to look for the Milky Way, which from truly dark skies appears bright enough to cast a shadow.[80] Measuring the effect of sky glow on a global scale is a complex procedure. The natural atmosphere is not completely dark, even in the absence of terrestrial sources of light and illumination from the Moon. This is caused by two main sources: airglow and scattered light. Prospective observers can report their results online by comparing the number of stars seen in the night sky with a set of template images that depict the stars’ visibility in varying levels of light pollution. Participation is open to anyone, anywhere in the world, who can get outside and look skyward. The anthropic principle is based on the observation that any small change in any of the basic constants of physics, which include the speed of light, would make human life impossible. I ought to emphasize that one expectation of this solution to the light travel time problem is that we probably are looking at the entire universe in something close to real time, regardless of how far away individual objects may be. Exactly at what point we begin to see light from certain stars that have traveled to us in the “normal way” rather than in the Day Four miracle, I have no clue. Hopefully, further discussion along these lines may help, though, given the miraculous nature of this solution, no clear answer may be possible. The Check Engine light — more formally known as the Malfunction Indicator Lamp (MIL) — is a signal from the car’s engine computer that something is wrong. The car dealer’s service department can diagnose the problem for about $75. But there’s a way to preview what the problem might be. Light pollution is artificial light introduced into the natural night, especially where it is not needed or wanted. This unwanted light appears We will not fit a shade to new LED street lighting for the first 3 months after installation. If there is still an issue after 3 months, please report the problem. While light of any kind can suppress the secretion of melatonin, blue light at night does so more powerfully. Harvard researchers and their colleagues conducted an experiment comparing the effects of 6.5 hours of exposure to blue light to exposure to green light of comparable brightness. The blue light suppressed melatonin for about twice as long as the green light and shifted circadian rhythms by twice as much (3 hours vs. 1.5 hours). To report a streetlight that’s out or malfunctioning, complete the form below (*Required). I’m trying to explain some LED-lighting phenomena, that we (me and my family) have observed, while changing light bulbs into LEDs. I’ve had some courses in semiconductor physics, and I’ve had a basic course in electronics, but I still have some difficulties in explaining these phenomena. VigRX Plus power up premium Maxman deseo Testogen Zevs TestX Core Masculin Active deseo Erozon Max

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