Transcript [] Planets, airplanes, birds

Planets, airplanes, birds
• Requires specialized knowledge to be
useful – buyer beware!
– Must be a true student of these with “local
knowledge”
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Planets for navigation/steering
Airplane routes
Shipping lanes
Birds
Phosphorescence
Planets and navigation
• Typically can use three planets for
navigation – Venus, Mars and Jupiter
– The rest are too dim
• Useful websites
– www.celnav.de/ragha.htm
– www.ephemeris.com
• Motions wrt stars depends on both the
earth’s orbit and planet’s orbit
• Hence the name: wanderers
Steering by the planets
• For latitude/longitude calculation, must
know SHA and declination – from tables
• For steering, rough positions can be used
one night after the next to hold a course
• Like the sun and stars, planets move
westward by 1o per day
• Eastward motion against background of
stars at varying rates
Motions of Planets
• Venus – always close to the sun, never further
than 30o
– Morning star, evening star
– Visible only up to two hours after sunset or before
sunrise.
– Has been mistaken for a boat or a train
– Moves east against fixed background of stars
• Jupiter – slow moving – roughly one sign of the
zodiac per year
• Mars – in between
Current positions 19 Oct 08
• Jupiter
– Decl: -22o 55’ , JH SHA: 73o 29’ W
– Two weeks: -22o 39’, JH SHA: 71o W
– Visible just after sunset
• Mars
– Decl: -15o 0’ , JH SHA: 141o 47’
– Two weeks: -18o , JH SHA: 130o W
– Nearly hidden by sun, currently
• Venus
– Decl: -21o 29’, JH SHA: 121o 9’ W
– Two weeks: -25o, JH SHA: 100o W
– Close to the sun, next to Antares (25S, 113W)
• Sun
– Decl: -10o 19’, JH SHA: 155o 11’ W
– Two weeks: -16o, JH SHA: 140o W
Mars
Jupiter
Venus
Sun
Antares
Jupiter
Mars
Venus
Earth
Snapshot of the relative positions of Jupiter, Mars, Venus
Earth, Antares (distant) and the Sun now.
Tonight’s sky at 6 PM facing SW
Jupiter
Venus
Antares
Mars
Sun
Retrograde motion
As the earth overtakes a planet (superior retrograde) or a planet overtakes
the earth, the planet temporarily appears to be moving backwards against
a fixed background of stars.
Retrograde motion
of Mars 1997
NB – Jupiter is just
coming out of
retrograde
Airplanes
• Considerations for long distance flights
– Typically follow great circle routes
– Some changes in routing associated with jet
stream
– Fly at altitudes of 30,000 to 40,000 ft
– Speeds of roughly 500 mph
– Visible from contrails, or from reflections
during day
– Visible from nav/warning lights at night
Navigation and
warning lights on
aircraft.
New York to London
Chicago to Paris
San Francisco to Tokyo
Comments on routes
• Large population in cities in N. Hemisphere
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Great circle routes tend toward high latitudes
Even over the North Pole
Avoid equatorial regions
Largely East-West directionality
Incoming flights from Europe from NE to SW
Outgoing flights more depressed – WSW to ENE
• New England flights to Europe
– Outgoing flights 6 PM – 9 PM
– Incoming flights 12 PM-4 PM
Landing/takeoffs/holding/N.A routes
• Aircraft frequently make multiple turns on
approach to urban airports
– Still, landing/takeoffs will be approximately
along lines radiating from local airports
• Holding patterns – aircraft go on long oval
tracks
• Many N-S routes on the east and west
coast
• Many E-W routes in great plains, rockies.
Shipping lanes
• Like airplane routes, they often follow
great-circle routes
• However, are constrained by coastlines,
canals, etc.
• Pattern of shipping also constrained more
by manufacturing, natural resources (e.g.
oil) and population centers.
• Attracting help from a passing ship is very
difficult!
Birds
• Homing birds fly away from islands during
the day and fly home to their nests at
night.
– Ranges vary up to 100 miles out to sea
• Migratory birds like fly on certain pathways
at certain times of the years
• Pelagic birds wander in the open ocean
Homing birds
• Fly out to sea in search of food
• At sunrise or sunset, they fly directly toward land
• Can be used to “expand” the circle of landfinding
around an island – Polynesians
• Examples
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Puffins
Boobies
Frigate birds
Pelicans
• Don’t ignore the possibility that single birds seen
far out to sea are lost!
Expansion of circle of discovery of islands
in Carolines
Migratory birds
• Can act as homing birds during the
breeding season
• Fly long distances during migration season
– Leach’s petrel
– Jaegers
– Plovers
Pelagic birds
• Wander around the ocean – for all
practical purposes, aimlessly (some
migratory and homing component during
breeding season)
– Albatross
– Storm petrel
– Noddies
– Tropic birds
Sea birds of New England
• Classic shore birds
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Gulls
Cormorants
Terns
Plovers
• Waterfowl
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Common ducks
Eider ducks
Geese
Swans
Cormorant
Very common across
the globe.
Sits low in the water,
dives for fish.
Must spend time in the
sun to dry wings.
25 mile limit from land
Puffin
Mainly found in arctic and
sub arctic locations.
Don’t migrate.
100 miles from land,
will fly toward land at sunset
and sunrise
Eider duck
Migrate from arctic
to Cape Cod during
December.
Winter over
Rarely seen more than
10 miles out.
Herring gull
Very common
Seen far inland, following
rivers, etc.
Seen as far out as 50 miles
to sea.
Will return to land at dusk
Mostly not migratory
Laughing gull
Males have black head
during breeding season
(June-Sept).
Otherwise white.
During breeding, stays
within 50 miles of land.
Non-breeding, called
a “vagrant”.
Common terns
Sometimes called
Sea swallows.
During summer breeding
months, will be within
50 miles of land.
Will migrate along coast
South to Florida during
Winter.
Piping plover
Protected species
During breeding
season (Summer),
stays within 10 miles
of land.
Migrates south along
coast during winter
Birds of the tropics
• Distinctly different species found in the
tropical regions (Tropic of Cancer to Tropic
of Capricorn)
• Many particular species related to those
found further north
– Noddies – related to terns
– Cormorants
– Pelicans
Frigate bird
Classic form of wings
Holds feet along narrow
tail.
Seen up to 100 miles from
land, but always returns.
Boobies
Cross shape of wings
and beak are distinctive
characteristics
Like frigate birds,
these are one of the
better homing species
for the navigator.
75 mile range from land
Pelicans
Big pouches under
bills
Found less than
25 miles from land
Noddies
Forked tails
Members of
the tern family
Pelagic
Tropicbird
Long, thin tail
Will breed near
land during winter
months
Otherwise pelagic
Sooty shearwater
Hooked bill,
pelagic Atlantic
Ocean bird.
Pelagic
Storm petrel
Small, short
beak
Pelagic
Shows darting
motions along
water (thought
to save energy
in flight)
Albatross
Most have huge
wingspan
Pelagic, roaming over
large sections of the
oceans
Other phenomena
• Phosphorescence - “underwater lightning”
Te Lapa, continued
What is it? Some form of bioluminescence.
It even has an anomaly designation – GLW11
(Geophysical luminescence over Water 11