Light pollution, also known as photo pollution or luminous pollution, is excessive obtrusive light created by humans. It broadly refers to inefficient, unappealing and arguably unnecessary use of wasteful artificial light. Light pollution is adverse and expensive illumination being squandered away senselessly from exterior and interior buildings, advertising hoarding boards, lavish streetlights and commercial properties like offices, factories and sporting venues. It is severe in highly industrialized and densely populated areas of North America, Europe and Japan. Big cities in the Middle East and North Africa exhibit similar trends regarding light pollution. The areas of southern England, North America, Netherlands, Belgium, West Germany and Northern France have abnormally acute sky brightness. From the East to West American coast that extends up to the Canadian border extremely significant global light pollution can be evidently perceived. Kathmandu, Pokhara, Nepaljung, Narayanghat and Biratnagar are light polluted Nepalese cities. Prodigiously expended light can earnestly damage the environment.
Specific categories of light pollution include light trespass, over-illumination, glare, clutter and sky glow. Light trespass occurs when unwanted light enters one's property. Common light trespass problem arises when strong light beams shine into one’s window from outside that could trigger sleep deprivation and glaringly disturb one’s panorama of neighborhood. Inordinate use of light especially to lighten buildings induces over-illumination. Glare is agitated by copiously exuberant contrast between bright and dark areas in the field of view. Superfluously extravagant grouping of lights is known as clutter, which may generate confusion, distract persons from obstacles and potentially incite accidents. Clutter is particularly noticeable on roads of Kathmandu and other main cities in Nepal where the street lights are badly designed or where advertising is intensely lit. In many over-populated and developed cities we can witness queer sky glow. It is the combination of all light reflected from illuminated objects in addition to badly directed light that has escaped up into the sky and has eventually scattered by the atmosphere weirdly back towards the ground.
Different types of light pollution have been noticed in major cities world over. People living in such metropolis have been suffering unknowingly from various forms of light pollution. Lighting is responsible for one-fourth of all energy consumption worldwide. Over-illumination including non-beneficial upward direction of night-time lighting is tantamount to energy wastage that could be checked by improving lighting quality while reducing unwarranted energy use and curbing greenhouse gas emissions and lowering carelessly unthrifty energy costs. The overall cost of light pollution in USA was calculated to circa one billion US Dollars in 1998.
Perceiving fainter celestial objects have become stressfully difficult as contrast between stars and galaxies has been dwindling predominating due to sky glow. The visibility of diffuse nebulae and galaxies is also affected by light pollution. One simple method for estimating the darkness of any location is to locate our sprawling galaxy the Milky Way. Since light trespass can distressfully impede observations and annoy avid sky-gazers, new and modern telescopes are being built and erected increasingly on remote areas. Astronomers are now searching for dark sky destinations like our country for wondering and watching the mystifying marvels of the universe along with participating in the International Year of Astronomy (IAY2009) to celebrate the 400th anniversary of the first recorded astronomical observations with a telescope by Galileo Galilei in 1609 and the publication of Johannes Kepler's Astronomia nova that described the planetary motion for the first time. As declared by the 62nd General Assembly of the United Nations, detailed scheme for IAY2009 has been prepared by International Astronomical Union (IAU) and endorsed by UNESCO. Some 135 countries including Nepal are taking part in an unprecedented global scientific network with various astronomical events and activities taking place throughout 2009.
Medical research on effects of radically immoderate light-exposure on human body suggests that a variety of health hazards may be enkindled by light pollution. Lighting design textbooks set sound human health as dominating criterion for proper interior lighting. Over irradiation or improper spectral composition of light may evoke increased headache incidence and anxiety. Manifestations of diminishing sexual performance have been linked to lengthy daily exposure to moderate lighting on persons. Common standard of fluorescent lighting in offices are sufficient to elevate blood pressure by about eight points. Relatively high levels of light in office environments have lead to increased stress and worker errors. Studies have indicated nexus between exposure to light at night and risk of breast cancer, due to suppression of the normal nocturnal production of melatonin hormone. Shift work that involves circadian disruption was listed as vital probable carcinogen by the World Health Organization (WHO). Life exists with natural patterns of light and dark. So any disruption of those rhythms directly influences many aspects of animal behavior. Light pollution could confuse animal navigation and alter competitive interactions, change predator-prey relations and modify animal physiology.
Melatonin is naturally occurring hormone (chemical compound) found in humans, animals, and other living organisms, including algae. In humans, melatonin is produced by pea-sized pineal gland located in the center of the brain. The melatonin signal forms part of the system that regulates the circadian cycle by causing drowsiness and lowering the body temperature. Circadian rhythm is an approximate daily periodicity with roughly 24-hour cycle in biochemical, physiological or behavioral processes of living beings, including plants, animals, fungi and cyanobacteria. Production of melatonin that is dubbed the arcane hormone of the darkness is inhibited by light but permitted peculiarly by darkness. Secretion of melatonin as well as its amount in blood, peaks in the middle of the night and gradually falls during the night’s second half with normal variations in timing according to an individual's chronotype. Low light radiation represses melatonin production to some extent, but over-illumination can create significant suppression in melatonin production. Since it is principally blue light that subdues melatonin, wearing glasses that block blue light in the hours before bedtime may avoid melatonin loss.
It is generally agreed that many people require light to feel safe at night, but campaigners for curtailing light pollution often claim that inappropriately installed lighting can lead to decline in safety if measured objectively. International Dark-Sky Association asserts that scientific studies cannot convincingly show clear relationship between lighting and crime. As protection from the dangers of light pollution demands utmost importance for everybody, methods for diminishing light pollution have to be invariably adopted. Utilizing light sources of minimum intensity and accurately to accomplish the light's purpose could prevent light pollution. Light could be switched off by using timer, occupancy sensor or even manually when not needed. Lighting fixtures could be improved and appropriate light types for specific purposes could be introduced. Government should evaluate and redesign existing and future lighting plans. Light pollution is presently a major challenge to the world and we should seriously make efforts to face and tackle it before it becomes too late for saving our environment with same emphasis and vigor while confronting water and air pollution.
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NASO team heading towards Programme venue (Gd Pudasaini, Sudeep Neupane, Suresh Bhattarai and Riwaj Pokhrel from the left)
Programme hall (DDC hall)
Mr. Sudeep Neupane giving talk on LIGHT POLLUTION
Mr. Suresh Bhattarai Giving talk on WHAT IS ASTRONOMY?
Mr. Sudeep Neupane Presenting slides on STEPS INTO AMATEUR ASTRONOMY
Observers watching Night sky from Binoculars
Students observing JUPITER and MOON through Telescope and Binoculars
Star Party on Stone Bridge sec. school, Dhangadhi