1 hrly gs ch 02 earth movement
DESCRIPTION
TRANSCRIPT
Earth Movement
Axis of Earth
• What is Axis?
Earth's axis is the imaginary line which goes through the north and south poles and around which Earth spins.
• Think of Earth as a Giant
Spin top
Tilted Axis
• Earth axis is Tilted/Inclined at an angle of 66.5 degrees to the plane of its orbit.
Angle from Plane is 66.5 Degree
Earth’s Hemispheres
NORTHERN HEMISPHERE
SOUTHERN HEMISPHERE
EARTH MOVEMENT• Earth is in a constant motion and performs
two different movements:
• Rotation around it’sAxis.
• Revolution aroundSun
Rotation of Earth
• Causes Day & Night
• It takes approx. 24 Hours for earth to complete one rotation around it’s Axis.
• The side of Earth facing Sun has Day while the side away has Night.
• Earth rotation is anti-clockwise
• Because of which:
- Sunrises in the east
- Sun travels across
the sky
- Sunsets in the west
Effects of Tilt
• Difference in the Length
of Day & Night.
• Different
Seasons
at same
time.
Revolution of Earth
• Revolution is the movement of one object around another object.
• Earth is revolving around Sun and completes one Revolution In 365 Days and 6 Hours
• Solar year = 365 and ¼ days
• Calendar = 365 days
• Difference = ¼ days or 6 hours in a year
¼ + ¼ + ¼ + ¼ = 1 day
Leap Year
• To compensate for every extra 6 Hours, a day is added to the calendar after every four years as 29th February:
Leap Year = Last two Figure of Desired Year
4
• If answer has no remainder it is a leap year.
Leap Year or not?
• 1934
• 1956
• 1978
• 1994
Not a leap year
Leap year
Not a leap year
Not a leap year
Seasons• This revolution of Earth is constant along
with the Axial Tilt which gives us different seasons
• As Earth revolves, at different places the seasons
occur.
Summer Solstice
Autumnal
Equinox
Winter Solstice
Spring Equinox
Summer WinterSolstice Solstice
• At Equinox March 21st & September 23rd
all places have equal Day and Night.
Moon
High / Low Tides
• As Earth & Moon attract each other toward themselves like two magnets.
• The moon tries to pull at anything on the Earth to bring it closer.
• But, the Earth is able to hold onto everything except the water. Because it is constantly moving and that allows moon to attract it
• This gravitation results in high and low tides each day. And Ocean moves from high tide to low tide and vice versa.
• As the moon travels around the earth and as they, together, travel around the sun, the combined gravitational forces cause the world's oceans to rise and fall.
Eclipse
• Definition– An obscuring of the light from one celestial
body by the passage of another between it
• There are two kinds of Eclipse but both occur as a result of relative positions of earth moon and sun
- Solar Eclipse
- Lunar Eclipse
Solar Eclipse
• When Moon comes between Sun & Earth.
• An eclipse of the sun occurs when the moon revolving in its orbit around the earth comes between the sun and the earth. The moon blocks the light of the sun and a shadow of the moon is cast over the earth's surface.
Types of Solar Eclipse
• There are two types of solar eclipse:
– Total solar eclipse– Annular solar eclipse– Partial solar eclipse
• Total Solar Eclipse– When the moon completely obscures the sun
• Partial Solar Eclipse– When the Sun and Moon are not exactly in line and
the Moon only partially obscures the Sun
• Annular Solar Eclipse– When the Sun and Moon are exactly in line, but the
apparent size of the Moon is smaller than that of the Sun. Hence the Sun appears as a very bright ring surrounding the outline of the Moon
Type Date Region
Annular May 20 China, Japan, Pacific, West U.S.
Total Nov 13 North Australia, South Pacific
Solar Eclipses in 2012
Lunar Eclipse
• When Earth comes between Sun and Moon
• A lunar eclipse is when the Earth comes between the Sun and the Moon causing a shadow of Earth on the Moon.
Can be viewed with naked eye
Types of Lunar Eclipse
• There are two types of solar eclipse:
– Total lunar eclipse– Partial lunar eclipse
• Total Lunar Eclipse– When the Moon travels completely into the
Earth’s umbra
• Partial Lunar Eclipse– When only a portion of the Moon enters the
umbra
Type Date Region
Partial Jun 04 Asia, Aus., Pacific, Americas
Lunar Eclipses in 2012