Le but de cette présentation était de sensibiliser les élèves et leurs professeurs sur les effets de la pollution lumineuse sur l'environnement et sur l'observation astronomique.

1. LIGHT POLLUTION
Students
Sophia Berberidou
Evi Siskou
Charoula Stefanakidou
Mpampis Simeonidis
Dimitria Chatziapostolou
Teachers
Panagiotis Ioannidis
George Mistax
Thodoris Mitsiakis

2. LIGHT 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.

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

4. INTRODUCTION TO TERMS
 Urbansky 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.

5. Light trespass
Clutter
Glare

6. 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.

7. Source: World Atlas of Artificial Night Sky Brightness

8.  Light pollution in Europe (left) and
Greece (right)

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

10. EXCESSIVE 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

11. EFFECTS OF LIGHT POLLUTION
 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.

13. EFFECTS OF LIGHT POLLUTION
 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.

14. EFFECTS OF LIGHT POLLUTION
 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.

15. In astronomy, limiting magnitude
is the faintest apparent magnitude
of a celestial body that is detectable
or detected by a given instrument.
 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“.

16. HOW DO WE MEASURE LIGHT POLLUTION
John Bortle‘s Light Pollution Scale
 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

17. JOHN BORTLE‘S LIGHT POLLUTION SCALE
 Class 1: The zodiacal light and  Class 5: Only hints of the zodiacal
zodiacal band are all very visible. To light are seen. The Milky Way is
the unaided eye the limiting very weak/invisible. The naked-eye
magnitude is 7.6-8.0. limit is 5.6-6.0.
 Class 2: Airglow may be weakly  Class 6: No trace of the zodiacal
apparent. The zodiacal light is still light. Only few indications of the
bright. The limiting naked-eye Milky Way. The naked-eye limit is
magnitude is 7.1-7.5. about 5.5.
 Class 3: Some indication of light  Class 7: The entire sky has a vague,
pollution is evident. The Milky Way grayish white color. The Milky Way
still appears complex. The naked-eye is totally invisible. The naked-eye
limiting magnitude is 6.6-7.0. limiting magnitude is 5.0.
 Class 4: Obvious light-pollution. The  Class 8: The sky glows whitish gray
zodiacal light is clearly visible. The or orangish. The naked eye can pick
Milky Way has only the most out stars down to magnitude 4.5 at
obvious structure. The maximum best.
naked-eye limiting magnitude is  Class 9: The entire sky is brightly
6.1-6.5. lit. Many stars are invisible The
naked-eye limiting magnitude is 4.0
or less.

18. PHOTO/79297308@N00/3180280752
ORION, 8 JANUARY 2009, 10:29:34, FROM HTTP://FLICKR.COM/
The
constellation
Orion,
imaged at
left from
dark skies,
and at right
from the
teeming
metropolis of
Orem

19. NIGHT SKY WITH LIGHT POLLUTION (LEFT) AND
NIGHT SKY WITHOUT LIGHT POLLUTION (RIGHT)

20. Picture of
Saturn’s
satellite, Titan,
with high light PHOTOS TAKEN
pollution levels BY THE STUDENTS
OF 2 GE.L. OF
ND
EHEDOROS, FOR
THE
DETERMINATION
OF SATURN AND
TITAN’S DISTANCE
AND OF THE
Picture of ORBITAL PERIOD
Saturn’s
satellite, Titan,
OF TITAN.
with low light
pollution levels

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

22. REFERENCES
 http://en.wikipedia.org/wiki/Light_pollution
 http://www.astrovox.gr/lightpollution.html
 http://www.darksky.org/
 http://skytonight.com/resources/darksky/3304011.html
 http://www.novac.com/lp/def.php
 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. 1801
K Street, NW Suite 500 Washington DC, 20006 with XENERGY, Inc.
Burlington, MA; September 2002.