A Powerpoint Presentation by Astronomer Robert Gillette

Slide 1
New Hampshire’s Dark Skies: A Natural
Resource in Need of Protection
• A Few Easy
Steps for
Preserving
Our Dark
Skies – At
No Cost
Slide 2
There’s so much
to see if the sky
is dark!
Slide 3
Visible in
NH: Comet
Macholz
Skims by the
Pleiades in
January
2005
Slide 4
Making Star-Trails: Mount a digital camera
on a tripod, point it at Polaris (the North
Star) and leave the shutter open for an hour
or two
Slide 5
The Pinwheel Galaxy – Visible in small telescopes
Slide 6
Saturn: Visible with a small telescope from a
billion miles
Slide 7
The Sombrero Galaxy: Visible with a small telescope
from 27 million light-years away
Slide 8
The Beehive Star Cluster in the Winter Sky –
A Binocular View
Slide 9
The Globular Cluster in Hercules – Visible with
binoculars in summer
Slide 10
“Eskimo Nebula” as seen by the Hubble Space Telescope
Slide 11
Crab Nebula in Taurus: Shattered remains
of an exploded star, visible in daytime in
July, 1054 A.D. and by telescope now
Slide 12
• The Great Nebula in Orion – The Middle Star in His
“Sword”
Slide 13
The Pleiades – Winter’s Brightest Star Cluster
Slide 14
The Double Cluster in Perseus – Easy to see
with binoculars all year
Slide 15
The Andromeda Galaxy: Most distant object you
can see with the unaided eye (2.5 million light
years away) – and easy to find in our still-dark
skies.
Slide 16
Northern Lights on December 14, 2006: Visible only
in dark skies – which are as easy to save as they
are to lose.
Slide 17
Cassini Spacecraft’s
view from Saturn: The
pale blue dot below is
us…
Slide 18
With an added glow…
A satellite image shows intense urban light
pollution along the US East Coast
Slide 19
Digital Map of Light Pollution (in blue): Most of New
Hampshire’s night sky is still dark. Let’s keep it that way.
Slide 20
Only 10% of Americans can still see the stars as our
grandparents did.
How can we make sure that includes us?
Slide 21
The Problem:
• 1. Dense population = dense lighting
• 2. Unshielded lighting projects light up
• 3. Upward light reflects off dust,
moisture, causing “sky glow” =
Light Pollution
• 4. Sky glow washes out faint stars
Slide 22
Bad Lighting:
Intense and
poorly
shielded
Slide 23
Poorly shielded lighting wastes
energy: Why light up the
rooftops?
Slide 24
Upward sign lighting adds to “sky glow”
Slide 25
Solutions:
We can’t stop population growth, but
we can fix the lighting:
• 1. Properly Shielded lighting points all
light down, saves energy, avoids
irritating glare and “light trespass”
• 2. Use minimum necessary illumination
for the job
Slide 26
This “full cut-off” fixture allows no light above
the horizontal – and puts light where it’s
needed, on the ground
Slide 27
The Ossipee Library shows “Dark Sky”
fixtures can be attractive. And they cost no
more than polluting lights.
Slide 28
Downward sign lighting is thoughtful sign lighting
Slide 29
Bad: Wallpack (left) throws
light up and sideways,
wasting energy
Good: Shielded “shoebox”
fixture (right) directs light
downward, where it’s needed
Slide 30
Bad: Typical “Yard-Blaster” (left) throws
light up and sideways
Good: Opaque reflector (lamp inside)
directs light downward
Slide 31
Modify Existing Floodlights:
Angling light up (left) defeats
purpose of shielding. Point it
down.
Slide 32
Solutions: Simple regulations that
require fully shielded outdoor lights
1. The Night Sky is a natural resource that
needs protection. Ask your Conservation
Commission (CC) to get involved.
2. Urge your CC to propose simple regs to
Planning Board and Selectmen
3. Goal: Design standards for Site Plan Review
and Subdivisions (no town vote required)
and Zoning Ordinance (town vote required)
Slide 33
Is it Difficult?
• Doesn’t have to be. More than 30 NH
towns have adopted “Dark Sky”
lighting regs
• See the excellent backgrounder: NH
State OEP Tech Bulletin 16 from 2001
• For more information, see the
International Dark Sky Association at
www.darksky.org
Slide 34
Basic Night Sky Regs
1. New commercial lighting should be fully
shielded (“full cut-off”) to allow zero light
above the horizontal
2. Sign lighting should be directed downward
3. Minimum necessary illumination by IESNA
standards (Illuminating Engineering Society
of North America)
4. Exceptions for flags, seasonal, emergency
lighting; existing fixtures grandfathered
Slide 35
What about Streetlights?
• Often a major source of sky glow
• PSNH wants to help
• They will install modern, energy-saving lights
with full-cutoff fixtures if asked
• No up-front cost to towns
• Towns pay by energy saved
• Talk to PSNH about a Streetlight Conversion
Program for your town
• NH Cooperative also promotes Dark Skies
Slide 36
The Bottom Line
• The night sky is a natural and scenic
resource of rural New Hampshire
• It’s part of what tourists come to see
• Preserving the night sky poses no
economic burden
• Good fixtures cost no more than bad
• Simple regulations requiring “DarkSky” certified fixtures will do the job
• It’s mainly a matter of awareness
--Robert Gillette, Ossipee
Slide 37
Credits
All photos by amateur astronomers except as noted
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Comet Swan – Gerald Rheman / www.astrostudio.at
Milky Way, Comet Macholz, Crab Nebula, Saturn, Orion Nebula,
– Johannes Schedler / www.panther-observatory.com
Star Trails – Josch Hambsch / www.astronomie.be/hambsch/
Pinwheel Galaxy – Dr. Steven Mazlin /
www.fourthdimensiona stroimaging.com
Sombrero Galaxy – Ken Crawford / www.rdelsol.com
Beehive, Hercules, Pleiades, Double Cluster, Andromeda
Galaxy – Dr. Robert Gendler /www.robgendlerastropics. com
Aurora – Stan Richards / www.nightskyevents.org
Lighting Photos from Ossipee – Robert Gillette
Diagrams from the International Dark Sky Association /
www.darksky.org
Satellite image of nighttime earth - NASA