by RON KURTUS 18 June 2010and MATT WILLIAMS 21 Nov. 2014
The Earth is constantly in
motion, revolving
around the Sun and
rotating on its axis.
The spinning
of an object on
its axis.
The Earth spins on its axis
from West to East
(counter-clockwise).
The spin axis of the
Earth undergoes a motion
This changing of direction of
the spin axis is called
PRECESSION
It takes the Earth 23
hours, 56 minutes, and 4.09
seconds to complete one
full turn.
Day and night are produced
by the rotation of the Earth.
The speed of rotation at any point upon the
equator is at the rate of
approximately 1,038 miles per hour, decreasing
to zero at the poles.
The Earth's polar axis tilts at an
angle of 23.5° with its orbital plane
around the sun.
This declination
is responsible
for the seasons
experienced on Earth!
SUMMERThe sunlight shines more directly on
the Earth and less sunlight is reflected
WINTER The angle of
the sunlight is steeper,
resulting in more light
being reflected
SUMMER
Summer daylight
hours are longer
WINTER
Winter daylight
hours are fewer
SUMMERIn Northern
and southern hemisphere,
sun goes more nearly overhead.
WINTERFor Northern
and Southern hemisphere, in the winter we
look to the south to see
the Sun.
Seasons are reversed in
the Northern and
Southern Hemispheres
.
Solstices and Equinoxes
The solstices are days when the Sun reaches its farthest northern and southern declinations.
Solstices and Equinoxes
While, equinoxes are days in which day and night are of equal duration.
Solstices and Equinoxes
SolsticesSummer Solstices: The Sun is farthest north and the length of time between Sunrise and Sunset is the longest of the year.
Winter Solstices: The Sun is farthest south and the length of time between Sunrise and Sunset is the shortest of the year.
Equinoxes
Autumn Equinox :The first day of the Season of Autumn - and the beginning of a long period of darkness at the Pole.
Spring Equinox The first day of the Season of Spring - and the beginning of a long period of sunlight at the Pole.
The movement of the Earth in its orbit.
The Earth is revolving around the Sun in a counter-clockwise direction.
It completes one revolution every 365.242199 mean solar days.
It travels to its path is known as the Earth's orbit that has an eccentricity of less than 0.02
It means that the orbit is very close to being circular.
The average distance of the Earth from the Sun is about 93 million miles but it varies as it orbits
Perihelion Aphelion
The speed of the Earth’s orbit around the Sun is 108,000 km/h.
The Earth also follows the Sun's movement through the Milky Way Galaxy.
The Sun and its planets are moving toward the star Vega at a velocity of about 12 miles per second.
The Sun and Vega are rotating about the center of the Milky Way at about 150 miles per second.
The Moon has a nearly circular orbit (e=0.05) which is tilted
about 5° to the plane of the
Earth's orbit.
Its average distance from
the Earth is 384,400 km
It takes the Moon 27.322 days to go around the
Earth once.
The Moon appears to move
about 13° against the stars
each day, or about one-half
degree per hour
Far-Side of the
The same side of the moon always faces the Earth.
Far-Side of the
Because of the effect on the Moon of tidal forces due to the Earth
Far-Side of the
It takes the Moon the same amount of time to rotate around once as it does for the Moon to go around the Earth once.
The Moon appears to go through a complete set of phases as viewed from the Earth because of its motion around the Earth .