Download 1.1 Safety in the Science Classroom

q discuss the variation in day length over a year for different latitudes
Day Length
= the time when the sun appears above the horizon,
from sunrise to sunset
There is still daylight after sunset. This period of
time is called twilight.
Length of a day depends on an area’s latitude
(= the distance from the equator) and the tilt
of the earth’s axis.
The rotation of the earth, along with the
latitudes, causes some interesting things:
a) At a given latitude, the duration of the longest day in the northern
hemisphere (on or about June 21) is the same as the duration of the longest
day in the southern hemisphere (on or about December 21);
b) Also, the duration of the shortest day in the northern hemisphere (on or
about December 21) is the same as the duration of the shortest day in the
southern hemisphere (on or about June 21);
c) The Arctic Circle is the southernmost latitude where 24-hour daylight can
occur at least on one day of a year (northern summer solstice on or about
June 21);
d) The Antarctic Circle is the northernmost latitude where 24-hour daylight can
occur at least on one day of a year (southern summer solstice on or about
December 21).
(Above) Pictures of the sun taken 1 hour apart. This and the following images were
from a scientific expedition in Antarctica, at a base located approximately 75o South.
(Above)Although DdU is a little south of the Antarctic circle, the sun is always visible at noon, even at the darkest of the winter. The reason is
because of the refraction of light on the low atmosphere layers: you can actually see it while it's somewhat below the horizon. This picture was
taken on June 21st with 9 exposures set 11 minutes apart if I remember right. One hour of sunlight is all we get in winter. Enough to go for a walk,
but little else. I created my animated HR bar starting from this picture.
•Each pole has only one sunrise and one sunset per year, around the time of the equinoxes. Each pole’s
sunrise is nearly coincidental with the other’s sunset.
Evidence That Shows The Earth Rotates About Its Axis
And Revolves Around The Sun
1) Foucault’s Pendulum
a) 1851- Foucault suspended a 60-m pendulum
weighing about 25kg from the domed ceiling
of the Pantheon in Paris.
b) He started the pendulum swinging evenly by
drawing it to one side with a cord and then
burning the cord to start the pendulum
swinging.
c) The direction of swing of the pendulum was
recorded on a ring of sand placed on a table
beneath its point of suspension.
d) At the end of each swing a pointed stylus
attached to the bottom of the bob cut a notch
in the sand.
e) After a few moments it became apparent
that the plane of oscillation (swing) of the
pendulum was slowly changing with respect
to the ring of sand, and hence with respect
to the Earth.
Foucault’s Pendulum in the Pantheon in Paris
The pendulum bob (left) weighed 28 kg and was brass-coated lead. It
was suspended from a wire 67 meters long! This replica in the
Pantheon in Paris has been permanently swinging since 1995.
These drawings show the pattern that emerged when the
pendulum was set in motion.
(left) The blue arcs show the pendulum swing; the green
lines show the pattern left in the sand. Each pass was
11° different from the previous pass.
http://www.youtube.com/watch
?v=6oYvffE6iGY&feature=relat
2) The Earth isn't round. It bulges around the equator, just as you would expect if it rotated. This
was known when Foucault made his pendulum.
http://earthsky.org/brightest-stars/altair-the-bluish-jewel-of-theeagle
Altair needs only 10 hours to spin once on its axis, in contrast
to roughly a month for our sun. This mighty star spins on its
axis more rapidly than Earth!
3) Coriolis Effect
1) Because each and every part of the Earth
rotates full circle in 24 hours, different parts of
the face of the Earth are actually moving through
space at different speeds.
2) A point on the equator of the Earth moves
about 24,000 miles in 24 hours, or about 1000
miles per hour.
3) On the other hand, a piece of ground 4 feet
from the North Pole moves only 24 feet in 24
hours, for a slow speed of 1 foot per hour!
Here’s an animation:
http://www.classzone.com/books/earth_science/terc/content/visualizati
ons/es1904/es1904page01.cfm
Or two:
http://www.bing.com/videos/search?q=coriolis+animation&qpvt=corioli
s+animation&FORM=VDRE#view=detail&mid=F1A36B32B7AC44BE6
B5DF1A36B32B7AC44BE6B5D
Or three: https://www.youtube.com/watch?v=dt_XJp77-mk
FUNKY NOTE:
The Coriolis Effect was largely a curiosity until World War I,
when the Germans built a generation of long-range cannons and
found that they could not hit anything if they aimed directly
at it; they had to aim to the left. (If the target was exactly
east or west of the gun's position, the gun would be aimed
directly at it.)
If you understand this discussion, you should be able to
convince yourself that a cannonball fired southward (toward
the equator) from some point in the Northern Hemisphere will
be deflected to its right (west).
Effects such as these that come about because we live on a
rotating frame of reference are referred to as Coriolis
effects.
The Motion Of Stars And Planets Are Caused By Rotation And
Revolution Of The Earth
1) The earth’s axis is in line with one Northern
Hemisphere star: Polaris.
2) Polaris is part of the Little Dipper (Ursa Minor)
3) It is found by drawing a line from the outer lip
of the Big Dipper (part of Ursa Major).
4) Polaris is located 10 off to the side of the north
celestial pole, so it makes a very small arc as the
earth rotates
5) All stars and planets rotate around Polaris
Polaris
Left: Star rotation
shown by a long
exposure. The star in
the middle is Polaris.
http://www.nakedeyeplanets.com
Above: A shooting star and a passing satellite
caught by a long exposure photography.
5C Earth, Moon and Sun Interactions
 Humans have been aware of the relationships between the Earth, Sun and Moon
for thousands of years, but only recently have we began to better understand the
true nature of these relationships.
1) Ancient civilizations used the seasons, months, position of stars and other
astronomical information in many parts of their lives.
2) Until the past few hundred years, humans believed the Earth was the center of the
universe (the geocentric model).
 The geocentric model was based on the work of the ancient Greek philosopher
Ptolemy
This drawing
from
an Icelandic
manuscript
dated around
1750
illustrates the
geocentric
model.
Figure 3.
Dante Alighieri's (1265-1321)
scheme of the universe in
illustration from "Paradies" in
"The Divine Comedy" extends
Aristotelian cosmology in a
modern way. Dante traverses the
material world from the icy core
of Earth, the abode of Lucifer, to
the Mount of Purgatory. He
continues through the nine
heavenly spheres, each sphere
larger and more rapidly turning
than the last, until he reaches the
Primum Mobile, the ninth and
largest sphere and the boundary
of space. His goal was to see the
Empyrean, the abode of God.
Map of the Square and Stationary Earth, by Orlando Ferguson (1893)
Figure 4.
The first diagram to illustrate the
proposal that the universe is infinite.
From the edition by Thomas Digges of
his father's A Prognostication
everlastinge..., published in 1576 in
London, eight years before its
publication by Giordano Bruno to
whom the idea is often credited
(By permission of The Royal Society).
Notwithstanding the fact that celestial
objects of a certain mass generally
are spherical in shape, an article
in My Magazine, dated May 1918
(and titled What the World May
Come To: The School Maps As They
May Be in Millions of Years to
Come) predicts that the earth is
spinning itself into a tetrahedron.
The explanation, as one can
imagine, is very dodgy. The
accompanying picture of the globe is
strange enough to be figured here.
Men of science believe that in millions of
years the earth will lose the shape of a globe
and become a sort of pyramid or tetrahedron.
The earth was formed as a round globe. In
cooling down the Poles were flattened and its
surface was fixed. But the core is still cooling
and shrinking, and the hard unshrinking
surface must adjust itself to a smaller bulk.
The shape of a globe is the shape that gives
the biggest possible surface for its size; but
there is another shape that gives the smallest
possible surface for its size, and the earth
seems likely to assume this shape. It is a sort
of pyramid shape, and is called a tetrahedron.
CREATIONSTORY
Red Jacket / Seneca
To fully appreciate the narrative of the Great Laws, one must first hear and understand the origin story of theHaudenosaunee, these
People of the Long House. According to these origin stories, the first person on the earth was a woman. Her name was Sky-Woman. There are
variations of this story, but many are similar to the following:
There is a Celestial world above where man-beings dwell—where even animals and all living things today were all once manbeings. There was no sun, but this world was lit by white blossoms on the great Celestial Tree standing in front of the lodge of the presiding
chief.
In this world was a young girl who had lost her father. She so grieved for him that they took her to his burial place. Here she was content
to stay and visit. Her father began speaking to her from the other side. He taught her many things. When she became of age, he told her that she
should marry the Sky Chief and directed her as to how this should happen. She followed her fathersinstructions so as not to talk to anyone but
the Sky Chief.
This chief had a dream, and according this, he took a young wife. It is said that in time this young wife was soon to become a mother
from inhaling the breath of her husband, but this was unknown to him. That from this, he doubted her honesty to him, so much that it caused him
so much distress in his mind, that he became ill from his jealousy. He had another dream which called for the Tree of Light to be uprooted
creating a great hole in sky world. Into this hole he could push his young and unsuspecting wife..
In olden times, dreams were held in high regard in everyday life, so much that destiny was controlled by dreams to a great degree. So,
accordingly, in the morning he called his wife to him. He had her get her burden basket and he began to fill it with nut tree roots and berry bushed
and many other things. Then he had this Tree of Light uprooted. The opening made by uprooting the Tree allowed light to shine through the
opening. Thus, today, comes the light of the Sun.
This chief managed to deceive his unsuspecting wife to look down through the new opening. In so doing, while she was looking down, he
pushed her down into the opening. It is said that in his anger, he also cast down through the opening all man-beings, such as the Deer, the Wolf,
the Bear, the Beaver, and all animals and growing things such as the sunflower and red willow. He transformed them into their forms and size as
they now appear. And when his anger had cooled down, he had the Tree of Light replaced.
Thus, the great change was brought about. It was the beginning of the present world, and all the living things as they are now.
Sky-Woman—then falling through the hole of the upper world—was seen by the water animals and water fowl of the great sea. These
beings are like man-beings who at once took up the task of making ready a place for her to live. All the larger birds flew up to meet her and with
their wings interlaced received her and brought her down.
While this was being done, the best divers among the water animals tried to get some earth that had fallen from the Sky World. One
animal would swim down but it was so far that its lifeless body floated to the top. Others tried but never came back up. After a while the animals
became reluctant to try to get some soil At last, the Muskrat succeeded to bring up a scoop of wet earth from the bottom,. However it was so far
and she had exerted herself so that now her lifeless body floated up. The other animals rushed out to help her and discovered the soil on her
paws. They took it and they placed on the back of Great Snapping Turtle’s shell, who volunteered to hold up the earth, and who at the time was
also a man-being like the rest of them. This wet earth placed on the shell soon expanded in size in all directions, and Sky-Woman was gently
placed on it.
At once, the Sky-Woman began to walk about this tiny earth, which by her action began to grow in size. She even took handfuls of earth
and cast it in all directions, which also caused it to continue to grow, until she could not see the boundary.
Thus, this is how North America became known as Turtle Island.
http://www.gly.uga.edu/railsback
/CS/CSIndex.html
3) We now observe the heliocentric model, where the Sun is the center of the solar
system, and the universe expands outward.
 The heliocentric model is based on the observations of Copernicus and
Galileo in the 1500s and 1600s…
Nicolaus Copernicus, early16th
century, described the first
computational system explicitly
tied to a heliocentric model
In the early17th century
AD Galileo Galilei opposed the
Roman Catholic Church by his
strong support for
heliocentrism
Andreas Cellarius's illustration of the
Copernican system, from the Harmonia
Macrocosmica (1660)
Unless you lived in India a thousand years
earlier. Then you had it right much sooner than
Kepler and Copernicus if you knew about this
guy.
Aryabhata (476–550), in his magnum opus Aryabhatiya (499),
propounded a planetary model in which the Earth was taken to be
spinning on its axis and the periods of the planets were given with
respect to the Sun.
He accurately calculated many astronomical constants, such as the
periods of the planets, times of the solar and lunar eclipses, and the
instantaneous motion of the Moon.
The Moon
See page 412
 Earth’s nearest neighbour in space is the Moon, a natural satellite that
most likely formed from a collision between the Earth and a Mars-sized
planet during the formation of the solar system.
1. The surface of the Moon, which can be seen
clearly with good binoculars, is not protected by
an atmosphere like the Earth’s.
2. The surface of the Moon is bombarded with
space debris, but also does not suffer from
erosional forces like wind and water.
3. Light-coloured surfaces are highlands made of
very old rock, while darker surfaces are called
mare, and are lower, flat stretches of basalt.
Phases of the Moon

The Moon, reflecting light from the
Sun, appears to change in size and
shape as it rotates on its axis and
revolves around the Earth.
1)
It takes the Moon 29.5 days to
make a complete orbit around the
Earth. During this time, different
portions of the Moon can be
viewed as the changing phases.
 Interestingly, the Moon
rotates at almost the same
rate as it revolves, meaning
that the same surface of the
Moon (the “near” side) always
faces the Earth. The “far” side
is always facing away from
the Earth!
 What we see as the changing
phases are actually just
different viewing points of the
Moon’s “daylight”, time
periods when the Sun shines
on the Moon.
See pages 412 - 413
2) The Moon’s gravity pulls on the
oceans on Earth to create tides.
Seymour Narrows
Surge Narrows Provincial Park
1875: The USS Saranac runs around on the famed Ripple Rock
off British Columbia and sinks. The side-wheel steamer sloop of
war had previously served with the Union army in the Civil War.
In 1979, the William J. Stewart was purchased by the Oak Bay
Marine Group of Victoria, renamed the Canadian Princess and
refurbished. She was then towed to Ucluelet harbour where she
now operates as a floating hotel/salmon fishing resort.
Barge at Ripple Rock.
This barge was Plan A for a design to
destroy Ripple Rock
The anchor cables kept snapping,
and another route to the rock was
needed. The rock needed to be
removed. 110 people had died in
shipwrecks.
http://www.sitnews.us/Kiffer/RippleRock/092305_ripple_
rock.html
Two diagrams of Plan B. Did it work?
The Earth’s Rotation and Tilt
See pages 414 - 415
 The time it takes the Earth to revolve around the Sun is 365 days (one year). Every 23
hours and 56 minutes (one day), the Earth rotates on its axis. The tilt of the Earth’s
axis gives us seasons.
1) As the Earth rotates, it is tilted at 23.5º from vertical. Depending on what part of the
year (orbit around the Sun) and which hemisphere (North or South) you are at, your
location will either be tilted toward the Sun (summer) or away (winter).
2) At the equator, the Sun’s energy strikes the Earth the same all year long - in other
words, there are no seasons!
3) It is this tilt that also changes the length of the daylight hours each part of the Earth
receives.
4) The shortest day (Winter solstice) occurs when we are tilted the most away from the
Sun, while the longest day (Summer solstice) occur when the tilt is closest to the Sun.
5) The Spring and Autumnal equinoxes occur when the number of hours of light and dark
are equal.
Eclipses
See pages 416 - 418
 An eclipse occurs when a celestial object obscures the normal view of another
celestial object.
1) Eclipses frightened ancient peoples, who believed supernatural forces controlled
the Sun and Moon.
Lunar eclipse panic. Historical artwork of men firing
rifles at a lunar eclipse (top right corner) to ward off
"evil spirits". The eclipse occurred over
Constantinople, Turkey in 1877.
2) Solar eclipses occur when the Moon comes between the Earth and the Sun.
Normal daylight disappears, and only small amounts of light make it to the
Earth during the few minutes it takes the Moon to pass between the Earth and
Sun.
 The Moon is so small, its full shadow only covers a small portion of the
Earth. This area is said to undergo a total eclipse.
3) Lunar eclipses occur when the Earth comes between the Moon and the Sun.
The Earth’s shadow causes the full moon to slowly disappear, again taking a
few minutes before the shadow passes.
 Lunar eclipses happen far more frequently than solar eclipses.
Constellations and Meteors

Ancient civilizations studied
the night sky for patterns, and
created many myths based on
patterns they recognized from
their lives.
 The night sky appears to
be flat because of the huge
distances between stars,
but actually the stars in
one constellation can be
several thousand, or even
millions, of light years
apart!
 In the northern
hemisphere, the “pointer
stars” of Ursa Major show
the location of the North
Star, Polaris. The location
of Polaris is special, as it
does not change position
throughout the year,
unlike all other stars.
See pages 419 - 420
 Meteoroids are pieces of space rock floating through space
without a specific orbit.
 When they pass through the Earth’s atmosphere, they begin
to heat from friction, and are called shooting stars.
 If any of the meteoroid reaches the Earth’s surface, it is
called a meteorite.
Meteor Explodes Over Russia, Leaving Nearly 1,000 Injured,
Up to $33M In Damages [PHOTOS/VIDEO]
By Fionna Agomuoh | February 15 2013 1:50 PM
The meteor that exploded over Chelyabinsk, Russia, early Friday
has left the city’s residents in a panic as reports indicate that
nearly 1,000 people have now sought medical attention.