2. Some earlier ideas on how the moon was
formed:
• the moon is a sister world that formed in orbit
Earth as the Earth formed
• the moon formed somewhere else in the solar
where there was little iron, and then was captured
into orbit around Earth
• early Earth spun so fast that it spun off the moon,
idea would produce a moon similar to Earth's
3. THE GIANT IMPACT THEORY
• Proposed by William Hartmann and Donald Davis in
1975
• It is the idea that a catastrophic collision about 4.5
BYA between Earth and a protoplanet about half the
Earth’s size created a disk of molten rock, gas, and
debris consolidated to form the moon
4.
5.
6. MEASUREMENTS
Kinds of Measurement Measurement
Equatorial Circumference 40 075.16 km
Diameter 12 756.32 km
Radius 6 378.1 km
Polar Circumference 40,008 km
Diameter 12, 713.54 km
Radius 6 356.8 km2
Area Total Surface Area 509 700 000 km2
Land 148 400 000 km2
Water 361 300 000 km2
7. Age of Earth Approx. 4.5 billion years old
Distance from sun 149,597,870.7 km
Mass 5.974 x 1027 kg
Density 5.52 g/cm3
Surface gravity 9.8 m/s2
Equatorial inclination 23.50
Highest part Mt. Everest at 8 848 m above sea level
Lowest part Shore of the Dead Sea at 429 m below sea
level
Deepest part of the ocean Part of Mariana’s Trench at 11 033 m below
surface
Highest recorded temperature 58 degrees Celsius at Al Aziziyah, Libya
Lowest recorded temperature -89.2 degrees Celsius at Vostok Station,
Antarctica on July 21, 1983
8. EARTH’S MOTION
• Axis – an imaginary straight line running from the North
to the South Pole
• Rotation – spinning motion of Earth, counterclockwise at
km/min or 16 556 km/hr
-- Earth rotates on its own axis every 23 hrs, 56 mins, 4.09
sec
9.
10. • Revolution – Earth revolves around the Sun once every 365
days, 6 hrs, 9 min, 9.54 sec in a slightly elliptical orbit
oPerihelion – Earth is at its closest point in its orbit at 147 km, it
moves the fastest
oAphelion – Earth is at its farthest point in its orbit at 152 km, it
moves the slowest
• Axial Precession – The slow wobble of the Earth’s axis
-- the Earth’s reaction to the gravitational pull of the moon
and the sun on its equatorial bulge
-- It takes 26 000 years to complete one turn or wobble of
the Earth’s axis
11.
12. KEPLER’S THREE LAWS OF PLANETARY MOTION
• Introduced by Johannes Kepler
A.THE LAW OF ELLIPSES
path of the planets about the sun is elliptical in
shape, with the center of the sun being located
at one focus
13.
14. B. THE LAW OF EQUAL AREAS
An imaginary line drawn from the center of the sun
to the center of the planet will sweet out equal
in equal intervals of time
Speed at which planet moves through space is
constantly changing
Planet moves fastest when it is closest to the sun
and slowest when it is furthest from the sun
15.
16. C. THE LAW OF HARMONIES
The ratio of the squares of the periods of
any two planets is equal to the ratio of the
cubes of their average distances from the
sun
Comparison between the motion
characteristics of a single planet
This theory failed because it could not explain why the moon lacks iron
This failed when lunar rocks showed the same isotope composition as the Earth.
it failed when analysis of the total angular momentum and energy involved indicated that the present Earth-moon system could not form in this way.
Precessional movement of Earth. Earth rotates (white arrows) once a day around its rotational axis (red); this axis itself rotates slowly (white circle), completing a rotation in approximately 26,000 years
