Download File - Prairie Science

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Rotation is the
spinning of the Earth
on its axis.
You notice this when
day turns to night
The time for one
rotation is 24 hours.
The speed of
rotation 24,855
miles/24 hr or
1,038 miles/hr
Click image to view Earth’s rotation.
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A revolution occurs as the earth moves
around the sun.
Time for one revolution = 365 1/4 days =
8,766 hours
◦ This is why we have leap years every 4 years, to
make up for the ¼ day.
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The speed of earth’s revolution is about
29.8 km/s or 18 miles per second.
 Every
second, that you sit
in this classroom, the
Earth's orbital motion
carries you about 18
miles through space.
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The path an object takes as it
revolves around another object.
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Earth’s orbit is in the shape of an
eclipse.
◦ Because of this, earth is not always the same
distance away from the sun
◦ When the Earth is closest to the Sun: perihelion
◦ When the Earth is farthest from the Sun: aphelion
 Earth’s aphelion is about 152 million km away vs.
147 during perihelion.
A constellation is a group of stars that are organized in a
recognizable pattern.
Today there are around 88 recognized constellations, many come
from the ancient Greeks.
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Rotation
◦ Earths rotation make
the constellations
appear like they are
moving in the shape
of an arc
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Revolution
◦ During different
seasons, the
constellations are in
different locations in
the night sky.
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They way that the Earth revolves and
rotates determines “time”
We say one day is equal to one rotation
around Earth’s axis and a year is defined
as one revolution around the sun.
A month is based on the moon’s motion
around Earth.
◦ Determined by the period between successive
full moons (29.5 days).
◦ However, now a year is just broken into 12
months (number of full moons in a year not
always a whole number)
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We define noon as the time when the sun is
highest in the sky, but because of earth’s
rotation the sun is highest above different
locations at different times of day.
◦ 24 standard time zones
◦ Time set based on noon being when the sun is the
highest.
◦ About every 15 degrees (total 360) is a new time
zone.
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Because of the tilt of the Earth, the duration of
daylight is shorter during winter months
compared to summer months.
To take advantage of this, we set clocks 1
hour ahead in March in order to get an
additional hour of sun at night and in
November clocks are set back in order to
return to standard time.
Not all counties participate in Daylight Savings
time.
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Earth’s Axis is tilted at 23.5%. Earth’s Axis
always points toward the North star as it
revolves around the sun.
When the North Pole points toward the sun,
the northern hemisphere has longer periods
of daylight than the southern hemisphere.
◦ Higher concentration of solar energy=warmer
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When the North Pole points away from the
sun, the Southern Hemisphere has longer
periods of daylight.
◦ Not as high concentration of solar energy=cooler
• The Seasons Fall and Spring begin on days called
equinoxes.
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The moment when the sun passes over the
celestial equator.
◦ Imaginary line directly overhead the equator.
◦ Sun strikes equator at 90 degree angle
◦ Hours of sunlight and darkness are equal everywhere
on Earth that day.
 Autumnal equinox: September 22, 23 (fall in N.
hemisphere
 Vernal equinox: March 21, 22 (Spring in N.
Hemisphere
Summer
Winter
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June 21 or 22 is when the
North Poles tilt toward the
sun is the greatest.
Marks beginning of summer
in the N. Hemisphere.
The N. Hemisphere has the
most hours of daylight
during this day. The farther
north you are, the longer
day you have.
◦ North of arctic circle you
have 24 hours of sunlight.
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By December 21, 22 the
North Pole is tilted to the
farthest point away from
the sun.
Winter Solstice marks the
beginning of winter in the
N. Hemisphere.
During the winter solstice,
the N. Hemisphere has the
shortest amount of daylight
hours.
◦ Places north of the arctic
circle have 23 hours of
darkness
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Video:
https://www.youtube.com/watch?v=82pDYgGFjI
Homework: Quiz over oceans on
Wednesday…study
1. The Earth spinning on its axis.
Rotation
Revolution
2. Going around a larger body.
Rotation
Revolution
Revolution
3. 24 hours.
Rotation
Revolution
4. Causes the Earth’s seasons.
Rotation
Revolution
5. Creates a year.
Rotation
Revolution
6. The moon going around Earth.
Rotation
Revolution
Identify the motion being shown in each of these
pictures. Each team must write their answers for each
figure in the form of a question.
Figure #1
Rotation
Planet
Figure #2
Rotation
Revolution
Earth
Revolution