8/2/2019 Pages From Seasons_EarthSunDist

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2 SPACE SCI ENCE SEQ UENCE 6 -8

If its not distance, what DOES cause the seasons?

1. The Earth spins on its north-south axis, and thespin axis is tilted so that the North Pole points atthe North Star all the time. As the Earth revolvesaround the Sun, the northern hemisphere istilted toward the Sun at some times of the year(A) and away from the Sun at the other part ofthe year (B).

CommonMisconceptionsAbout Seasons

Many people thinkthat the Earths orbitaround the Sun is a

skinny (elongated)ellipse, causingEarths distancefrom the Sun tovary dramatically atdifferent points.

Many think that theSun is off-centerwithin our orbit,

again causing Earthto be closer or fartheraway from the Sun atdifferent times.

Some people know that theEarths tilt has somethingto do with the seasons,

and they think that thetilt makes us signicantlycloser to the Sun at certaintimes of the year.

People say, Whenthe Earth is closerto the Sun, we havesummer; when theEarth is farther fromthe Sun, we havewinter.

Whats wrongwith thoseideas?

The Earths orbitis indeed elliptical,but it is not at all

skinny. It is verynearly a perfect circle.

True, the Sun is atone focus of Earthselliptical orbit, but

the orbit is so nearlycircular that theEarth-Sun distanceremains very nearlyconstant throughoutthe year.

The tilt of the Earth is a keyfactor, but the tilt does notmake any signicant differ-

ence in the distance to theSun. Because the distancefrom the Earth to the Sun isso enormous, the differencein distance caused by the tiltis not signicant.

SeSSion 1

idas abuh earhad Gravy

Unit 2

Why ArthrSass?

Many of us hold onto andembellish our erroneouspersonal explanations for theseasons throughout all the yearsof school, and we become verygood at tting new informationinto our old, comfortable private

models. Our students often dothe same. They arrive in classwith their own frameworks andpreconceptions, sometimes alsocalled alternate conceptions.

No single experience is likely tomove all of your students fromtheir initial conceptions to a full andaccurate understanding. Researchindicates that one of the best waysto get people to correct their miscon-ceptions is to provide them with

revealing experiences and allow timefor them to compare and discussalternative ideas/explanations sothey themselves discover the awsin their own thinking.

2. When the Northern Hemisphere is tiltedtoward the Sun, it has summer because:

a. There are more hours of daylight.

b. Sunlight strikes the NorthernHemisphere at a higher angle (moreperpendicular), making the sunlightmore intense on the ground (orwater), and resulting in more heating.

Source: http://www.lawrencehallofscience.org/pass/passv14/Seasons_EarthSunDist.pdf