with average distance of 92,955,820 miles (149,597,890
km) from the sun,
is the third planet and one of the
most unique planets in the solar system.
It formed around 4.5-4.6 billion years
ago and is the only planet known to
presence of water over 70.8% of
the planet allow life to thrive.
Earth is also the fifth largest planet
in the entire solar system.
Earth has an estimated mass
of 5.9736 × 10 24 kg.
Its volume is also the largest
of these planets at
108.321 × 10 10km.
Earth is the densest of the
terrestrial planets as it is made
up of a crust, mantle and core.
As the earth revolves around the sun,
Earth’s axis remains tilted at 23.5°
The north end of the axis points
toward the north star (Polaris)
Earth rotates 360° from west to east
(counter clockwise looking down from the
north pole) in 24 hours, at an angular rate
of l5° per hour (360°/24 hours =
• • 1851, Foucault’s pendulum will appear
to change in a predictable way.
• • Why is this evidence? There is no
force acting on the pendulum to make
its plane of oscillation rotate or go
around its own axis
• • It would continue to swing in the
original path if Earth did not rotate.
•1. Evidence of Earth’s Rotation
• • Coriolis Effect – the tendency of objects
moving over the earth (air, water, planes, projectiles)
to be deflected (curve away) from a straight line
path. The French scientist, Gaspard Coriolis, first
explained the deflection of objects moving over the
surface due to Earth’s rotation
• • The deflection is to the right in the Northern
Hemisphere and to the left in the Southern
• • This deflection occurs because Earth’s surface
is rotating with respect to the objects.
•2. Evidence for Rotation
• Earth revolves around the sun in a
slightly eccentric elliptical orbit or path once
• It takes Earth 365.25 days to revolve
360° in its orbit around the sun. It moves
approximately 1° per day. (360°/365.26
days = 1° per day)
• Aphelion – the point on the Earth’s orbit
is farthest from the sun.(Early in July)
• Perihelion – the point of the Earth’s
orbit is nearest the sun.(January)
• • Seasonal Constellations: Because
of the Sun’s annual motion, some
constellations are visible at night
only during certain seasons.
• • Constellations are visible when
the dark side of Earth (away from
sun) faces toward the constellation.
•Evidence of Earth’s Revolution around the Sun
•The 12 constellations the sun appears to travel
through during the year
• • Because of Earth’s revolution about
the sun, near stars seem to shift their
position against the farther stars (closer
star – greater the shift)
• • If you observe the same star while
earth is at 2 different points during its
orbit around the sun, the star’s position
relative to the more distant background
stars will appear to change.
Evidence of Revolution: Parallax Shift
• • The sun is nearer the center of the sky; rays fall directly to the
ground and the radiation is more intense and more concentrated.
• • The hottest time of the year.
• • This begins about June 22 in the northern hemisphere
and December 22 in the southern hemisphere.
• • The sun is lower; nearer the horizon.
• • Heating is less intense and the nights are longer than the day.
• • Longer night of the year occurs in December 22 in the north and
June 22 in the south.
•The Earth’s Seasons
SPRING OR VERNAL EQUINOX
• • All parts of the earth receive the same amount of
• • Daytime is equal to night time
• • In the Northern Hemisphere, it begins on the 21st
day of March.
AUTUMN OR FALL EQUINOX
• • Direct rays of the sun strike the equator.
• • 12 hours of days and nights throughout the world.
• • In the Northern Hemisphere, it starts on the
23rd day of September.
It is conical movement of the Earth’s axis
around a line joining the poles.
It lasts for a period of 25,780 years
It is like the conical motion of a spinning top but
opposite in direction to that of the rotation of
This is the reason why our polar star keeps on
changing. During the building of the pyramids-
Thuban is the polar star and many years from
now, it will be the star Vega.
All places were located their distances
from two lines.
• Latitude - The north-south location of
any place on the earth.
• Longitude – The east-west position of a
Parallels of Latitude
-Changes in location in a north or south
direction are described by just such a system of
lines parallel with the equator.
• North Latitude
• - includes all the parallels that can be
drawn between the equator and the north
• - includes those parallels between the
equator and the south pole.
- Imaginary Lines
- Longitude line
• Time measured with a sundial is called
“Apparent solar time”.
• (Perihelion) Nearest the sun
• - 91,300,000 miles from the sun.
• (Aphelion) Farthest point
• - 94,500,000 miles.
• Average Distance
• - 92,900,000 miles.
•Time by the Sun