- describe the shape of the Earth and the relative position of the poles
Looking up at the sky on a clear night is surely
invokes feelings of curiosity, wonder and awe at the sight of stars,
planets, “shooting stars” and faraway galaxies. For millennia, humans
have been gazing at the sky and experiencing those same emotions. One
of the very first sciences was the observation and recording of the
positions of the stars, as we can see from relics such as Stonehenge,
the Great Pyramids and medicine wheels of the Native Americans. With
these chronicles of the sky, astronomy was born.
Full moon (Grant Dakin)
how do you tell which way is which, when the night sky is black in all
directions, the positions of the stars seem to change by the hour and
the patterns of stars in the sky change by the season? Early
astronomers realized they needed a frame of reference.
History of Astronomy in Canada
medicine wheels - large circular configurations of stones thought to
indicate positions of stars on significant dates - were first
constructed approximately 2200 years ago, on the northern plains of
Alberta and Saskatchewan. Remnants of over 20 medicine wheels have been
found in the two provinces, and which are still being excavated and
The planet Earth, like most planets, is approximates in the shape of a
sphere. The poles of a planet are the topmost and bottommost points on
the sphere, while the equator circles the Earth halfway between the two
poles, dividing the planet into two hemispheres. On Earth, our
“topmost” pole is the North Pole, while the South Pole is on the
“bottom” of the planet. The equator therefore divides the planet into a
Northern and Southern hemisphere.
The Earth can be divided into northern and southern
Did you know?
hemispheres, divided by the equator. Size of the Sun
and distance to the Sun are not to scale.
Earth is not a perfect sphere! As a result of the Earth’s rotation it
is wider at the equator and flatter at the poles, making it look like a
slightly flattened ball. This is caused by the spinning of the Earth.
Imagine a filled water balloon that is spinning. The water is pushed
as far out as possible in the middle and it ends up being flattened on
the top and bottom.
The poles also serve as an axis
around which the planet rotates. When seen from space, the Earth
rotates from left to right. Imagine looking down on the Earth from
above the North Pole: you would see that it rotates counter-clockwise.