Movement of the Earth

Earth’s

Movemements

• astronomical unit: the average distance between the earth and the sun –150 million km

–93 million miles

Earth has 2 Movements:

Rotation: is the turning or spinning of a body on its axis

1) 1 rotation = 24 hours = 1 day

Rotation & Revolution

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What effect (that we see daily) does rotation cause?

DAY NIGHT & 2) Causes:

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3) is in the direction from West to East…

• Sun appears to be moving East to West

• Sunrise in East

& sunset in West

http://tm.an.ask.com/r?t=an&s=p&uid=04D1F290C8103EF14&sid=1CDF54EA0CE2A5324&qid=90C1834AC4B6EA489E965F7267FE5FDA&io=13&sv=za5cb793e&o=0&ask=compass&uip=d03f72b9&en=js&eo=0&pt=&ac=15&qs=31&pg=2&u=http://pictures.ask.com/redir?u=http%3a%2f%2flrs.ed.uiuc.edu%2fstudents%2ftbarcalow%2fQuilt%2fHattie%2fColorQuilt.htm&bpg=http%3a%2f%2fpictures.ask.com%2fpictures%3fq%3dcompass%26o%3d0%26page%3d2&q=compass&s=p&bu=http%3a%2f%2flrs.ed.uiuc.edu%2fstudents%2ftbarcalow%2fQuilt%2fHattie%2fColorQuilt.htm&qte=0&o=0&isimageSearch=true&fromImagePage=False&iskey=&thumbsrc=http%3a%2f%2fimages.picsearch.com%2fis%3f97897571787&imagesrc=http%3a%2f%2flrs.ed.uiuc.edu%2fstudents%2ftbarcalow%2fQuilt%2fHattie%2fcompass.gif&thumbwidth=128&thumbheight=123

Movement #2 … REVOLUTION

is Earth’s movement around the sun

Revolution cont.

1 Revolution= 365.24 days = 1 year

.24 x4 = 1 day Leap Year!

Speed of Revolution =30km/s=70,000 mph

ORBIT: is the path Earth follows

Earth’s Orbit is:

• Slightly elliptical (not a perfect circle)

• Earth is NOT always the same distance from the sun

PERIHELION

closest point to the sun at:

147 million km = (91.34 million miles)

and occurs on: Jan 3rd

PERI=near Helio=Sun

APHELION

farthest point from sun at:

152 million km =

94.45 million miles

And occurs on: July 4th

Ap=away Helio=Sun

Kepler’s Laws of Planetary Motion

• 1st law : planets orbit the sun in a path called an ellipse

aphelion

perihelion

• 2nd law: planets move fastest when they are closest to the sun in their orbits

• 3rd law: the farther away a planet orbits, the longer the planet takes to revolve around the sun

Tilt of Earth’s Axis

is 23.5 degrees

Always pointed toward North

Star

What effect does this cause?? seasons

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This causes the: Seasons! 1) Longest days & most direct sunlight=Summer

2) Shortest days and least direct sunlight=

Winter

What effect does this cause?? seasons

http://tm.wc.ask.com/r?t=an&s=p&uid=04D1F290C8103EF14&sid=1E2F78E23AEAB5324&qid=702DF09C9F0EEC47AFF9D5F5EC1EAC89&io=4&sv=za5cb0d71&o=0&ask=tilt+of+earth&uip=d03f72b9&en=is&eo=0&pt=&ac=6&qs=1&pg=1&u=http://pictures.ask.com/redir?u=http%3a%2f%2fwww1.thny.bbc.co.uk%2fscience%2fspace%2fsolarsystem%2fearth%2fsolsticescience.shtml&bpg=http%3a%2f%2fpictures.ask.com%2fpictures%3fq%3dtilt%2bof%2bearth%26o%3d0%26page%3d1&q=tilt+of+earth&s=p&bu=http%3a%2f%2fwww1.thny.bbc.co.uk%2fscience%2fspace%2fsolarsystem%2fearth%2fsolsticescience.shtml&qte=0&o=0&isimageSearch=true&fromImagePage=False&iskey=&thumbsrc=http%3a%2f%2fimages.picsearch.com%2fis%3f508877961953&imagesrc=http%3a%2f%2fwww1.thny.bbc.co.uk%2fscience%2fspace%2fsolarsystem%2fimages%2fearth_tilt.jpg&thumbwidth=126&thumbheight=128

Precession is: • the gravitational pull of the moon that

causes Earth’s axis to wobble and spin like a top

• Earth makes 1 full turn every 26,000 years

• North Star will NOT always be where North Pole points

Earth’s other movements

Precession: The axis points in different directions!

Nutation – the rocking or wiggling motion on the axis of rotation -Earth’s nutation period is 18.6 years

-The effect is a small change in Earth’s tilt towards the sun

- Result is a slight shift in location of: Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle

Barycenter – the point between 2 objects where they balance each other - The center of mass between 2 or more celestial bodies that orbit each other - Both bodies orbit around a point that is NOT the center of the larger body

http://www.youtube.com/watch?v=1iSR3Yw6FXo

http://www.youtube.com/watch?v=1iSR3Yw6FXo

Earth’s

circumference Video: Earth’s Equatorial Bulge

Video: Shape of

Earth

Earth’s

Circumference

http://geography.about.com/library/faq/blqzcircumference.htmhttp://geography.about.com/library/faq/blqzcircumference.htmhttp://www.youtube.com/watch?v=uXiRupBxI9Qhttp://www.youtube.com/watch?v=HGrgitTXhBYhttp://www.youtube.com/watch?v=HGrgitTXhBY