Transcript 4.3 Earth`s Revolution

EARTH’S MOTIONS
4.3 EARTHS REVOLUTION
EARTH’S REVOLUTION
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REVOLUTION – ONE COMPLETE
ORBIT AROUND THE SUN = 1
YEAR
PARALLELISM- TILT OF AXIS IS
PARALLEL THROUGHOUT OUR
ORBIT (N. STAR)
LENGTH OF DAYLIGHT
DEPENDS ON TWO THINGS:
1. TILT OF AXIS
2. POSITION IN ORBIT – CAUSES SEASONS
Sun’s rays
PROOF OF REVOLUTION
PARRALAX – APPARENT SHIFT IN POSITION OF
NEARBY STARS.
PATH AND RATE OF REVOLUTION
EARTH’S ORBIT IS ELLIPTICAL
AVERAGE DISTANCE 93,000,000 MILES (150 MILLION
KM)
APHELION – POINT IN EARTH’S ORBIT WHEN
FARTHEST FROM THE SUN (JULY 4TH )
PERIHELION – POINT IN EARTH’S ORBIT WHEN
NEAREST TO SUN (JAN 2ND )
http://www.classzone.com/books/earth_science/terc/content/visualiz
ations/es0408/es0408page01.cfm?chapter_no=visualization
EQUINOX
EQUINOX – EQUAL NIGHT SUN RISES DUE
EAST AND SETS DUE WEST
VERNAL – MARCH 21ST VERTICAL RAYS AT
EQUATOR. 12 HRS DAY AND 12 HRS NIGHT.
AUTUMNAL – SEPT 23RD VERTICAL RAYS AT
EQUATOR. 12 HRS DAY AND 12 HRS NIGHT
PLACE INTO YOUR NOTES WHICH WOULD BE
THE SPRING AND FALL EQUINOXES.
March 21–22
June 21–22
Dec. 21–22
Sept. 21–22
DO THE NORTH AND SOUTH POLES
EXPERIENCE THE SAME SEASONS?
OUR AXIS HAS NOT ALWAYS POINTED
TO THE SAME STAR AND WILL CHANGE
IN THE NEAR FUTURE.
HOW DO YOU THINK A DIFFERENCE
IN THE TILT OF THE EARTH WILL
AFFECT THE AMOUNT OF LIGHT AND
THE SEASON A POINT ON EARTH
WILL EXPERIENCE???
PRECESSION – Earth not only rotates on its axis …
it also wobbles. This wobble effect is a phenomenon
caused by forces exerted by the Sun on the bulges of
the Earth at the Equator.
THINK OF A SPINNING TOP AS IT BEGINS TO
SLOW DOWN.