Earth, Sun, Moon System Next Generation Science Standards. Develop and use a model of the Earth-sun-moon system to describe the cyclic patterns of lunar phases, eclipses of the sun and moon, and seasons.  [Clarification Statement: Examples of models can be physical, graphical, or conceptual.]

Equator is 0 Poles are 90 N and 90 S Latitude denotes distance north or south of the equator. Lines run parallel to one another. “latitude flatitude” Equator is 0 Poles are 90 N and 90 S

Prime Meridian goes through England Longitude lines run from N to S poles. Closer at the poles, farther from each other at the equator. These lines intersect latitudes at right angles. Prime Meridian goes through England

The Equator divides the globe into northern and southern hemispheres.

This is called Earth’s obliquity Earth is tilted at 23.5 o This is called Earth’s obliquity

Arctic Circle and Antarctic Circle 23.5 o north and south of the poles Within the circles formed by these latitudes, earth receives 0 or 24 hrs of sunlight twice a year. Arctic Circle and Antarctic Circle 23.5 o north and south of the poles

Sun’s rays make a 90 o angle The latitudes at which Sun’s rays make a 90 o angle With Earth’s surface. Other special lines of latitude: Tropic of Cancer and Tropic of Capricorn 23.5 o north and south of the Equator

Looking at the North Pole - counterclockwise Looking at the South Pole - clockwise

The Earth’s rotation causes us to experience what phenomena?

The Earth’s rotation causes us to experience what phenomena? Day and Night

Given that the sun “rises” in the east, about what time of day is it in location A, B, C, and D? Sun’s rays C

Which diagram accurately shows the direction of Earth’s spin from the North Pole? B N N

Because of Earth’s tilt. Why does daylight last for different amounts of time at different times of the year? Because of Earth’s tilt.

Does the sun rotate?

Which orbit most accurately shows Earth’s path around the sun? (Keep in mind the Earth is on average 107 sun-diameters away from the Sun)

This does not cause seasons! At its nearest point, Earth is 147,500,000 km from the sun. At its farthest point, it is 152,600,000 km from the sun. This is less than 3 % difference from nearest to farthest point. (NASA.gov) A To the eye, the orbit would appear as shown, This does not cause seasons!

Some planets have more of an ellipse than others. Perihelion – when a planet is closest to sun. Aphelion – when a planet is farthest from sun. dotted line - perfect circle solid line actual planet path + = sun

The line around the earth that divides light from dark is the circle of illumination.

The angle at which sun’s rays hit the Earth is the angle of incidence.

Think: How many degrees above the equator is the most direct sunlight? Earth in June The Northern Hemisphere is tilted towards the sun creating more hours of day light = summer. The Southern Hemisphere is titled away from the sun creating fewer hours of day light = winter. Think: How many degrees above the equator is the most direct sunlight?

Earth in December The Northern Hemisphere is titled away from the sun creating fewer hours of day light = winter. The Southern Hemisphere is tilted towards the sun creating more hours of day light = summer.

Autumnal/ Vernal Equinox Summer solstice Winter solstice Autumnal/ Vernal Equinox The Analemma

Solstices When the sun’s direct light is farthest from the equator. The sun’s direct light reaches its greatest distance north of the equator once each year. The sun’s direct light reaches its greatest distance south of the equator once each year. In the Northern Hemisphere Summer solstice June 20 - 22 “longest day of the year” Winter solstice Dec 21 or 22 “shortest day of the year”

Equinox Equinox - when the noon sun is directly overhead at the equator. Day and Night are each 12 hours long. Happens twice a year: Occurs March 21st (start of spring, NH) Occurs Sept. 22nd (start of fall, NH)

http://www.classzone.com/books/earth_science/terc/content/visualizations/es0408/es0408page01.cfm

not to scale.... and ellipse is exaggerated!

How long does it take the Earth to complete its orbit around the sun? 365.25 days Every 4 years, an extra day is added to the calendar! Next leap year: 2016

How long does it take the sun to revolve around the milky way? 200,000,000 years! If the Earth is 4.6 billion years old, how many times has it followed its orbit around the milkyway galaxy?