Section 1: Earth in Space

Discover Activity: What causes Day and Night? 1.Place a lamp with a bare bulb on a table to represent the sun. Put a globe at the end of the table about 1 meter away to represent Earth. 2.Turn the lamp on and darken the room. Which parts of the globe have light shining on them? Which parts are in shadow? 3.Find your location on the globe. Turn the globe once. Notice when it is lit – day – at your location and when it is dark – night. Think it Over What does one complete turn of the globe represent? In this model, how many seconds represent one day? How could you use the globe and bulb to represent a year?

Astronomy: the study of the moon, stars, and other objects in space I. How Earth Moves Earth moves through space in two major ways: rotation and revolution. A. Rotation: 1. axis- the imaginary line that passes through earth’s center and the North and South pole’s. 2. rotation- the spinning of Earth on its axis 3. causes day and night 4. takes 24 hours for the Earth to rotate once = a day

B. Revolution - the movement on one object around another. 1. earth travels around the sun 2. year = one complete revolution of Earth around the sun 3. orbit- a path that Earth follows as it revolves around the sun a. Earth’s orbit is elongated = ellipse (not circular)

C. Calendars – a system of organizing time that defines the beginning, length, and divisions of the year. 1. Egyptians = created the first = developed 365 days a. Moon Cycles = a year of 12 full moon cycles = 354 days b. Calendar = 12 months of 30 days each and 5 days at the end 2. Romans used this calendar and added one day every four years = “leap year”

II. The Seasons on Earth A. 4 seasons = winter, spring, summer, autumn 1. most places experience all 4 seasons B. Temperatures vary from place to place 1. warm near the equator C. How Sunlight hits earth- (Figure 4 pg. 10) 1. sun hits most directly at the equator 2. sun hits poles at a steep angle D. Earth’s Tilted Axis- 1. if earth axis were straight up and down = no seasons Earth has seasons bc its axis is tilted as it revolves around the sun

E. Earth in June - north end of Earth’s axis is tilted toward the sun 1. Northern Hemisphere = more hours of daylight than darkness (sun high in the sky) 2. Southern Hemisphere = it is winter…days are shorter than nights(sun low in the sky)

F. Earth in December – 1. Northern Hemisphere = Winter (less direct rays) 2. Southern Hemisphere = Summer G. Solstices – when the sun is at its greatest distance north or south of the equator 1. happens twice a year a. June 21 st and December 21 st

H. Equinoxes – means “equal night” …halfway b/n the solstices, neither hemisphere is tilted toward or away from the sun 1. the noon sun is directly overhead at the equator 2. occurs twice a year 3. day and night are about 12 hours long everywhere on earth 4. March 21 = vernal equinox (spring) 5. September 22 = autumnal equinox (fall begins)