Review Friday lesson #1 November 9, 2012 SEASONS Review Friday lesson #1 November 9, 2012

First we need to know…

SO…. LAT means FLAT Lines of LATITUDE run East to West but Measure North and South.

..LONGitude are the LONG lines… Lines of Longitude run North to South but Measure EAST to WEST

SO…why do we have seasons? The Earth’s axis is an imaginary line that goes through the center of the Earth from the north pole to the south pole. As the Earth spins on its axis it does not spin straight up and down. The Earth is tilted on its axis about 23.5 degrees from perpendicular. Bill nYe

SO.. Are the rays of the sun hitting earth directly everywhere?

So when the Earth revolves… It goes around the __SUN____. This takes EXACTLY _____365.256_______ days.

So when the Earth ROTATES… It takes EXACTLY ________ to make 1 full rotation. 23 hours, 56 minutes and 4 seconds 

IMPORTANT SUN DAYS… VERNAL equinox Summer SOLSTICE ATUMNAL equinox Winter SOLSTICE

It the revolution even? Nope….it an ellipse GREEK “Apo” is AWAY. “Peri” is near. “Helion” is SUN

AP and Peri ; HELION Perihelion and Aphelion Animation The closest point to the Sun in a planet's orbit is called perihelion. The furthest point is called aphelion. Notice how the planet moves fastest at perihelion and slowest at aphelion.

THIS IS NOT the reason for the seasons perihelion is about 147 million km (91 million miles) from the Sun. aphelion, it is 152 million km (almost 95 million miles) from the Sun. Earth reaches perihelion, its closest approach to the Sun and when you might think it should be warmest, in January - the middle of winter in the Northern Hemisphere!

SO… The ellipse (orbit of revolution’s lopsided shape) is not responsible for seasons. The earth’s tilt on axis is.

So NOW you know how it works. VIDEO Video 2

Important Places

TROPICS at 23.5ᵒ N or S The Tropic of Cancer (N) and the Tropic of Capricorn (S) each lie at 23.5ᵒ latitude. The tropics are the two lines where the sun is directly overhead at noon on the two solstices - near June and December 21.

EQUATOR 0ᵒ latitude On the equator, the sun is directly overhead at noon on the two equinoxes - near March and September 21. It is 24,901.55 miles (40,075.16 kilometers) long.