Download Earth, Moon & Sun System

Solar Motion
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MOTIONS OF THE EARTH
-DAY & NIGHT
Solar Motion
• Essential Question- Bell Ringer
• Why does the earth have day & night?
• Do other planets have day & night?
Solar Motion
• The Earth is a sphere (ball shape).
Because of this only half can be lit by
the sun at any one time.
Solar Motion
• The earth spins (rotates) on its axis.
• The earth rotates in a counterclockwise (west to east) direction
• It takes 24 hours for the earth to make
one complete spin
Solar Motion
• The half that is facing the sun, has light
(day)
• The half that is facing AWAY from the
sun has NO light (night)
• Planets & moons that rotate also have
day and night
Solar Motion
• Essential Question
• Why does the earth have seasons?
Do other planets have seasons?
Solar Motion
• Space objects are held in orbit by a force
called gravity (pull). Because of the pull of
gravity between the sun and the planets, the
planets follow a curved path (orbit) around the
sun, instead of traveling in a straight line out
into space.
Revolution
• The earth revolves (follows a path) around
the sun.
• The path it follows is called an orbit.
Revolution
• Distance from the sun ONLY affects:
– How long it takes for the planet to make
one complete trip around the sun (year)
• The farther away from the sun, the
larger the orbit, the longer time it takes
to make one complete trip around the
sun
• Distance from sun does NOT affect
temperature as long as we are in orbit
Solar Motion
As the earth moves around the
sun in its orbit, the tilt of the
axis stays the same.
Solar Motion
• As the earth moves in its orbit
around the sun, the position of Earth
in its revolution causes
– Sometimes the northern axis is leaning
toward the sun, sometimes away,
sometimes in between
Solar Motion
– Sometimes the northern axis is leaning
away from the sun
– Sometimes the northern axis doesn’t lean
either away or toward the sun
Solar Motion
If there was no tilt, the sun’s rays would
not hit the earth’s surface so
differently.
Note the differences in the places that
23 degree
have day.
No tilt to axis
tilt to axis
Solar Motion
Because the earth is a sphere and the
earth’s axis is tilted at about a 23 degree
angle,
– the sun’s rays do not hit earth’s surface
the same way if the northern axis is
pointed toward the sun as it does when
the northern axis is pointed away from
the sun
Northern
axis toward
the sun
Northern
axis away
from the
sun
Solar Motion
• When the northern axis is leaning towards
the sun, the northern hemisphere gets the
most direct rays
• Because of the position of earth in its
revolution, days are longer so the earth has
more time to absorb energy from the sun so
the days are hotter.
Solar Motion
• When the northern axis is leaning away
from the sun, the northern hemisphere
gets the least direct rays
• Because of the position of earth in its
revolution, days are shorter so the earth
has less time to absorb energy from the
sun so the days are cooler.
Solar Motion
• The winter solstice is the shortest day
& longest night of the year. (December
21)
• At the opposite side of the orbit, is
the summer solstice (the longest day
and the shortest night of the year.
June 21)
Solar Motion
• At the positions in earth’s orbit where
the hours of day & night are equal,
the northern axis is not leaning
toward or away from the sun.
• These days are called equinoxes. The
spring equinox is on March 21, the Fall
equinox is on September 23
Solar Motion
• The earth revolves in a counter-clockwise
motion around the sun.
• The days get longer between December and
June.
• The days get shorter between June and Dec.
Solar Motion
Planets that have a slight tilt
to their axis will also have
seasons
Solar Motion
• Essential Question
• Why do the sun, moon, & stars
APPEAR to rise in the east and set in
the west?
Solar Motion
• The earth rotates around its
action in a COUNTERCLOCKWISE direction.
• This causes the sun, moon, &
stars to APPEAR to rise in the
East and set in the West.
• The earth is actually the one
moving
Solar Motion
•In the summer, the sun makes a shorter
shadow at noon than in winter.
•This is because the sun is lower in the
sky.
Solar Motion
• The sun’s path across the sky is called the
ecliptic.
• The sun follows a different path in each
season.
Solar Motion
• In the Northern Hemisphere. the sun’s
path is higher in the sky in the summer.
• The sun follows a lower path (closer to
the horizon) in the sky in the winter.
Solar Motion
• In the Spring & Fall, the sun follows a
path that is higher than in winter,
but lower than in summer.
Solar Motion
Winter
noon
sunset
sunrise
Summer
Solar Motion
• Stars also seem to rise in the
East and set in the West
Solar Motion
• Stars that are above the North Pole
appear to rotate around the North Star
• This apparent motion is caused by the
earth’s rotation
Solar Motion
• An eclipse occurs when the sun, moon, &
earth line up.
• A solar eclipse occurs when the moon is
between the sun & earth and the moon
casts a shadow on the earth (blocks out the
sun)
Solar Motion
• Total Solar Eclipse
Solar Motion
A lunar eclipse occurs when the Earth
comes between the sun & moon. The
shadow of the earth covers part or all
of the moon.
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