360 likes | 645 Views
Sun-Earth-Moon System. Aristotle – “Earth is round because it casts a round shadow on the moon during an Eclipse.”. Earth. Aristotle (350 BC) – “Earth is round because it casts a round shadow on the moon. Earth is sphere – shaped Not a perfect sphere Bulges at equator Flattened at poles.
E N D
Aristotle – “Earth is round because it casts a round shadow on the moon during an Eclipse.”
Earth • Aristotle (350 BC) – “Earth is round because it casts a round shadow on the moon • Earth is sphere – shaped • Not a perfect sphere • Bulges at equator • Flattened at poles
Earth • Axis – imaginary line around which Earth spins • Earth’s axis tilted at 23.5 degrees • Rotation – spinning of the Earth on its axis (causes day and night) • 1 rotation = 24 hours Do the Math – if Earth rotates on its axis each day, how many degrees does the Earth rotate in 1 hour?
Earth …Earth rotates 1 time every ____ hours …there are ___________ degrees in a circle (rotation) Therefore… ___________ / ________ = ________ every hour Now…which direction does it rotate? Do the Math – if Earth rotates on its axis each day, how many degrees does the Earth rotate in 1 hour?
Earth • Magnetic field – North & South Magnetic poles • Magnetic axis – aligned 11.5 degrees off of rotational axis • Where does a compass needle point?
What Causes / affects Earth’s Seasons? • Earth’s tilt? • Earth’s orbit?
What Causes / affects Earth’s Seasons? Both • Earth’s tilt? • Earth’s orbit?
What Causes / affects Earth’s Seasons? • Earth’s tilt • Tilted at 23.5 degrees • Longer and more direct daylight for some • Shorter and less direct daylight for others
The amount of daylight for various cities throughout the year
What Causes / affects Earth’s Seasons? • Earth’s orbit • Ellipse – elongated circle • Distance between Earth and Sun changes throughout orbit • Closest to Sun – January (147 million miles) • Farthest from Sun – July (152 million miles)
Earth orbits around sun (360°) • 1 revolution = 365.25 days (1 year) • Earth’s orbit is not a circle, but an ellipse • Solstice = unequal amt. of sunlight/darkness • Equinox = equal amt. of sunlight/darkness Revolution
Equinox vs. Solstice • Equinox:“equal night” • 2 times per year • Sun directly over the equator • Daylight (12 hours) • Darkness (12 hours) • Neither the Northern or Southern Hemisphere is tilted toward the sun • Spring Equinox – March 20 or 21 • Autumn Equinox – September 22 or 23
Equinox vs. Solstice • Solstice: • 2 times per year • Sun reaches farthest North or South of equator • Daylight • Darkness • Either the Northern or Southern Hemisphere is tilted toward the sun • Summer Solstice– June 21 or 22 • Winter Solstice – December 21 or 22
How would our seasons be different if Earth’s axis was perpendicular to its plane of orbit?
How would our seasons be different if Earth’s axis was parallel to its plane of orbit?
What do we call the lines on a globe at 23.5 degrees North and South of the Equator? Tropic of Cancer Tropic of Capricorn Why are they significant? They represent the farthest North and South of the equator where the sun is directly overhead