L IGHT P OLLUTION Students Sophia Berberidou Evi Siskou Charoula Stefanakidou Mpampis Simeonidis Dimitria Chatziapostolou Teachers Panagiotis Ioannidis George Mistax Thodoris Mitsiakis

L IGHT POLLUTION Definition by IDA(International Dark-Sky Association): Any adverse effect of artificial light including sky glow, glare, light trespass, light clutter, decreased visibility at night, and energy waste.

R EAL MEANING :  Light pollution is the alteration of light levels in the outdoor environment (from those present naturally) due to man-made sources of light.  Light pollution is the introduction by humans, directly or indirectly, of artificial light into the environment.

I NTRODUCTION TO TERMS Urban sky glow: the brightening of the night sky over inhabited areas Light trespass: light falling where it ‘s not intended, wanted or needed Glare: excessive brightness which causes visual discomfort. High levels of glare can decrease visibility Clutter: bright, confusing and excessive groupings of light sources, commonly found in over-lit urban areas. The proliferation of clutter contributes to urban sky glow, trespass and glare.

Clutter Light trespass Glare

Glaring lights can actually reduce visibility. Here the brightest most visible objects in the area are the lighting fixtures, not the roadways, walkways or parking areas which a driver or pedestrian would expect to be lighted. Atlanta, Georgia.

Source: World Atlas of Artificial Night Sky Brightness

Light pollution in Europe (left) and Greece (right)

C AUSES OF LIGHT POLLUTION Within the atmosphere and uncontrollable Starlight Cosmic dust Particles in the air Atmosph eric dust Water vapors, humidity, clouds and fog Totally controllable: Environmental pollution Excessive outdoor lighting

E XCESSIVE OUTDOOR LIGHTING Over-lighted Parking Areas Commercial Establishments – Advertisements. Bad street lighting  Lamps send light upwards and not downwards, where it’s needed. 35% to 50% of all Light Pollution comes from Streetlights

E FFECTS OF L IGHT P OLLUTION Ecological  Disorientation of nocturnal animals and sea turtles from additional illumination which affects foraging, reproduction, communication, and other critical behaviors  Both bright days and dark nights are necessary to maintain healthy hormone production, cell function, and brain activity, as well as normal feeding, mating, and migratory behavior for many species, including humans.  The photosynthetic cycles of deciduous trees have been shown to be disrupted due to the predominance of artificial nighttime lights.

E FFECTS OF L IGHT P OLLUTION Financial-Social 30% of produced light goes to waste. Waste of light=energy waste  unnecessary nighttime lighting wastes upwards of $1.5 billion in electricity costs around the world per year. Well-planned lighting can save money, decrease crime and improve night-time ambiance. Contribution to the Greenhouse Effect Accounts for the release of more than 12 million tons of carbon dioxide, the leading greenhouse gas, into the atmosphere.

E FFECTS OF L IGHT P OLLUTION Obstruction of Night Sky Watch Increased urban sky glow reduces the contrast between stars and galaxies, making it difficult to detect fainter objects. The visibility of diffuse sky objects such as nebulae and galaxies is affected by light pollution more than are stars. Light trespass can impact observations when stray light enters the tube of the telescope, causing a glow across the field of view.

Amateur astronomers usually judge their skies by noting the magnitude of the faintest star visible to the naked eye. However, depends too much on a person's visual ability. One person's "5.5- magnitude sky" is another's "6.3-magnitude sky“. In astronomy, limiting magnitude is the faintest apparent magnitude of a celestial body that is detectable or detected by a given instrument.

H OW DO WE MEASURE LIGHT POLLUTION Class 1: Excellent dark-sky site - Black Class 2: Typical truly dark site - Gray Class 3: Rural sky - Blue Class 5: Suburban sky Class 6: Bright suburban sky Class 7: Suburban/urban transition. Class 8: City sky - white Class 9: Inner-city sky - White John Bortle‘s Light Pollution Scale

J OHN B ORTLE ‘ S L IGHT P OLLUTION S CALE Class 1 : The zodiacal light and zodiacal band are all very visible. To the unaided eye the limiting magnitude is Class 2 : Airglow may be weakly apparent. The zodiacal light is still bright. The limiting naked-eye magnitude is Class 3 : Some indication of light pollution is evident. The Milky Way still appears complex. The naked-eye limiting magnitude is Class 4 : Obvious light-pollution. The zodiacal light is clearly visible. The Milky Way has only the most obvious structure. The maximum naked-eye limiting magnitude is Class 5 : Only hints of the zodiacal light are seen. The Milky Way is very weak/invisible. The naked-eye limit is Class 6 : No trace of the zodiacal light. Only few indications of the Milky Way. The naked-eye limit is about 5.5. Class 7 : The entire sky has a vague, grayish white color. The Milky Way is totally invisible. The naked-eye limiting magnitude is 5.0. Class 8 : The sky glows whitish gray or orangish. The naked eye can pick out stars down to magnitude 4.5 at best. Class 9 : The entire sky is brightly lit. Many stars are invisible The naked-eye limiting magnitude is 4.0 or less.

O RION, 8 J ANUARY 2009, 10:29:34, FROM HTTP :// FLICKR. COM / PHOTO The constellation Orion, imaged at left from dark skies, and at right from the teeming metropolis of Orem

N IGHT SKY WITH LIGHT POLLUTION ( LEFT ) AND NIGHT SKY WITHOUT LIGHT POLLUTION ( RIGHT )

P HOTOS T AKEN B Y T HE S TUDENTS O F 2 ND G E.L. O F E HEDOROS, F OR T HE D ETERMINATION O F S ATURN A ND T ITAN ’ S D ISTANCE A ND O F T HE O RBITAL P ERIOD O F T ITAN. Picture of Saturn’s satellite, Titan, with high light pollution levels Picture of Saturn’s satellite, Titan, with low light pollution levels

Get involved Educate others Learn the facts about light pollution W HAT CAN WE DO ? Use light only when and where it’s needed. Use only as much light as needed. Shine lights down, not up. Use efficient light sources for outdoor lighting around homes and businesses.

R EFERENCES U.S. Lighting Market Characterization, Volume I: National Lighting Inventory and Energy Consumption Estimate - Received by Building Technologies Program; Office of Energy Efficiency and Renewable Energy; U.S. Department of Energy; Prepared by Navigant Consulting Inc K Street, NW Suite 500 Washington DC, with XENERGY, Inc. Burlington, MA; September 2002.