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!

SUMMER WINTER

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.

SUMMER WINTER

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 . 

Thank you!