lesson 5 motions of the earth
TRANSCRIPT
MOTIONSof the Earth
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Basic Understandings
Rotation –
the Earth spins on an imaginary line called ‘axis ‘ from east to west direction.
“The Earth spins on its axis once every 24 hours or 1 day.”
Major Motions of the Earth
Revolution –
movement around the Sun in an elliptical orbit.
Complete r = 365 ¼ days.
Speed = 29.8 km/s
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The Earth is farthest from the Sun at aphelion on July 3 or 4 at approx. 152.1 million kilometers.
The Earth is nearest from the Sun at perihelion on January 3 or 4 at approx. 147.2 million kilometers.
Basic Understandings
94,500,000 miles
93,000,000 miles
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EARTH'Smotion
around the Sun, not as
simple as you thought.
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The four important positions of the Earthwith respect to its revolution around the Sun.
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Seasonal Changes
-are caused by
the tilting of the
Earth and its
revolution around the Sun.
These bring
about the
variations in
the lengths of day and night.
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The Earth’s Tilted Axis and Seasonal Changes
As the Earth rotates and
revolves around the Sun, its
axis tilts at an average of 23.5 °from the vertical line.
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Seasonal Changes
When the longest
days and shortest
nights occur in Northern Hemisphere.
Summer
Warm weather
-when the North Pole
Is directly tilted toward the Sun.
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Seasonal Changes
-when the North
Pole is tilted awayfrom the Sun.
Winter
Cool weather
Earth will experience
the shortest day and
longest night of the year.
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Seasonal Changes
Days and nights are
equal all over the Earth.
Equinoxes
Equinox
- means equal day and night.
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Seasonal Changes
It tells the time
when the Sun stops
its journey to the
north as it rises everyday.
Solstice
Solstice - means “Sun stops”.
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The midnight sun is a natural phenomenon that occurs in the summer months
in places north of the Arctic Circle or south of the Antarctic Circle, when the sun remains visible at the local midnight.
Landof the
Midnight Sun
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The earth covers 360° in its 24-hour rotation. Thus, for every hour of rotation it covers 15 ° of longitude. This is the basis for determining time all over the globe.
Timeand
Standard Time Zones
Local Time -If we would base time on the Earth’s
rotation, covering 360° in a day, or
15° in an hour, or one degree every
four minutes, each meridian would
have its own time.
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STANDARD TIME ZONES OF THE WORLD
The Earth was divided into 24 time zones, each zone one
hours apart, covering approximately 15° of longitude.
STANDARD TIME ZONES OF THE WORLD
Therefore, the different places of the world have different
times based on the meridian passing through them.
Not all countries, however, follow the standard time system.
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Australia
Standard Time System
- was adapted based on the Greenwich Prime Meridian (0°) as agreed upon in an international conference held in Washington, D.C. in 1884.
Bigger countries
cover more than
one time zone.
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When one travels around the
world, crossing boundaries and
going from one hemisphere to
another, it is important to take
note of time differences as well as
the change in dates upon
crossing the
International Date Line.
Motions of the Earth
Revolution
Revolves around the sun.
Takes about a year or 365 ¼ days.
Causes changes in seasons.
Follows an elliptical orbit.
Rotation
Rotates on its axis.
Rotates for a period of 24 hours.
Causes night and day.
Rotates in an eastward direction.
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North Pole is directly tilted toward the Sun.
It occurs every June 21 or 22.
Longest day and shortest night are experienced.
Vertical rays of the Sun strike the Tropic of Cancer.
Seasons and the Positions of the Earth around the Sun with reference to the Northern Hemisphere
Summer solstice
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No pole is tilted toward the Sun.
It occurs every September 22 or 23.
Equal length of day and night is experienced.
Vertical rays of the Sun strike along the Equator.
Seasons and the Positions of the Earth around the Sun with reference to the Northern Hemisphere
Autumnal equinox
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South pole is directly tilted toward the Sun.
It occurs every December 21 or 22.
Shortest day and longest night are experienced.
Vertical rays of the Sun strike the Tropic of Capricorn.
Seasons and the Positions of the Earth around the Sun with reference to the Northern Hemisphere
Winter solstice
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No pole is tilted toward the Sun.
It occurs every March 21 or 22.
Equal length of day and night is experienced.
Vertical rays of the Sun strike along the equator.
Seasons and the Positions of the Earth around the Sun with reference to the Northern Hemisphere
Spring equinox
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Mechanism of the Seasons
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