it is specially for 7th std.

1. Earth Moon SunEarth Moon Sun
RelationshipsRelationships

2. RotationRotation versus Revolutionversus Revolution
• RotationRotation is the turning of a body about
an axis.
– The earth rotates once every 24 hours.
• RevolutionRevolution is the motion of one body
around another.
– The earth revolves around the sun once
every 364 ¼ days.

3. What is Insolation?What is Insolation?
InsolationInsolation is the amount of radiation per area
that reaches the earths surface. The more direct
the suns rays hit the surface, the greater the
amount of surface heating.

4. Examples of Insolation

5. Why Does the Length of Day onWhy Does the Length of Day on
Earth Change?Earth Change?
• The tilt of the Earth’s axistilt of the Earth’s axis, and the
rotation and revolution of the Earthrotation and revolution of the Earth
is responsible for the changes in the
length of day and night.

6. Equal Day and NightEqual Day and Night
Vernal and Autumnal EquinoxVernal and Autumnal Equinox
Sun is
directly
over the
Equator

7. Longer Days, Shorter NightsLonger Days, Shorter Nights
In Northern HemisphereIn Northern Hemisphere
Sun is
directly
over the
Tropic
of
Cancer

8. Shorter Days, Longer NightsShorter Days, Longer Nights
in Northern Hemispherein Northern Hemisphere
Sun is
directly
over the
Tropic of
Capricorn

9. Why Do We Have Seasons?Why Do We Have Seasons?
• The tilt of the Earth’s axistilt of the Earth’s axis and the
revolution around the Sunrevolution around the Sun cause the
Earth to have seasons.

10. Effects of axis tilt

11. Effects of revolutionEffects of revolution

12. Combined Effects of Tilt and RevolutionCombined Effects of Tilt and Revolution

13. Earth’s Seasons - YearEarth’s Seasons - Year

14. Why Does The Moon Have Phases?
• Phases of the moon are determined by:
– The relative positions of the earth, moon and
sun.
• Revolution of moon around the earth.
– Your position on the earth.

18. What is aWhat is a SolarSolar Eclipse?Eclipse?
• A SolarSolar Eclipse is when the SunSun is
blockedblocked from view by the moon.
– The moons orbital path places it in
between the earth and the sun.

21. PhasesPhases
of aof a
solarsolar
eclipseeclipse

22. Solar eclipse, notice
solar prominence in
carona.

23. SolarSolar
EclipseEclipse

24. What is a Lunar Eclipse?What is a Lunar Eclipse?
• A Lunar eclipse is when the moon is
blocked by the shadow of the earth.
– The moon’s orbital path takes it into
the shadow of the earth.

25. PhasesPhases
of aof a
LunarLunar
eclipseeclipse

26. Solar versus Lunar EclipseSolar versus Lunar Eclipse
Note: Solar eclipse = sun blocked; Lunar eclipse = moon blocked