Presentation on theme: "Seasons on Earth Butler Middle School 8th Grade Science"— Presentation transcript:
1 Seasons on Earth Butler Middle School 8th Grade Science Bob, Paul, Ms Adams, Oct 25, 2012
2 The Observed Data: 4 Seasons Autumn or FallWinterSpringSummerimgres
3 We can explain the 4 seasons using Models of the Earth and Sun
4 Scientific ModelRepresentation of an object for study and understanding (very common in Science)Models can be physical and/or conceptual Model leg in 7th grade life science Computer model of a large weather system
5 Spherical Earth ModelEquatorEarth rotates on N-S axis once per day
6 Earth-Sun Model (evolved over 100’s maybe 1000‘s of years) Earth revolves around the sun once per year + a little bit
7 Earth’s Orbital Plane to Polaris perpendicular to orbital plane Points to Polaris(North Star)to Polarisorbital planeperpendicularto orbital plane7
8 Rotate and RevolveRotation: spinning like a top Earth rotates on its axis once per 24hr Causes day & nightRevolution: 1 object moving around a 2nd object Earth revolves around sun once per year: days + 1/4 dayLeap Year Every 4 years February has an extra day4 years = ( ) = 1461 days
13 Understanding the Seasons It’s all in the tiltSummer: - Earth is tilted toward the sun, we get a more direct hit, so it’s warmerWinter: Earth is tilted away from the sun, we get a slanted hit, so it’s coolerNo tilt means 1 Season!
14 Understanding Summer and Winter Summer in the NorthWinter in the North☺☹S☺☹UnightdayNSouthSouthFrom summer to winter earthrevolves half-way around Sun
15 Special Days Vernal Equinox March 20 Winter Solstice Dec 21 Summer June 21Autumnal EquinoxSept 22Vernal EquinoxMarch 20
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