Definition of season as defined by dictionary.com:

Seasons are one of the four periods of the year (spring, summer, autumn, and winter), beginning astronomically at an equinox or solstice, but geographically at different dates in different climates.

Why do they happen?

Seasons occur on Earth because of its tilt. Earth is tilted 23°. So, at certain times of the year one part of the Earth is closer to the Sun than the other. The closer half would be summer and the farther part would be winter. There are four seasons in the temperate regions, and only two seasons near the equator and near the Polar Regions. The four seasons are:
Spring~ an Old English word meaning “to rise”.
Summer~ a Sanskrit word meaning half-year or half-season.
Autumn~ an Etruscan word for maturing
Winter~ an Old English word meaning wet or water

Near the equator the seasons are the dry season and the rainy season.

Near the Polar Regions there are the light, and the dark seasons.

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http://www.mrcrandall.com/terms/seasons_files/image002.png

A common misconception is that the seasons are warmer or colder because the Earth is closer or farther from the Sun. This is not true. Summer is warmer because there is more day as compared to night. Also the Sun’s rays hit the Earth more directly making it warmer.

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There are names for the days when the seasons officially begin; the vernal equinox and the autumnal equinox. At each of these days there are 12 hours of day and 12 hours of night.

How was it Discovered?

Seasons always were. It wasn’t something to be discovered, it is a part of the world we live in. The seasons told farmers of old when to plant and when to harvest. They told ancient tribes hunt and when to gather. They have always been apart of our existence.

Personal Views

I think my topic is interesting to learn about. It is neat to learn about why we have seasons and the reasoning behind it. This topic did not change my views in any way because they are apart of everyday life.

Sources

http://dictionary.reference.com/browse/seasons

Hoff, Darrel B. "Seasons." Gale Encyclopedia of Science. Ed. K. Lee Lerner and Brenda Wilmoth Lerner. 4th ed. Detroit: Gale Group, 2008. Student Resource Center - Silver. Gale. Christopher Dock Mennonite High School. 19 May. 2010 [[http://find.galegroup.com/srcx/infomark.do? &contentSet=GSRC &type=retrieve &tabID=T001 &prodId=SRC-2 &docId=EJ2644042044 &source=gale &srcprod=SRCC &userGroupName=pl2118 &version=1.0]].
"Seasons." UXL Encyclopedia of Science. Ed. Rob Nagel. 2nd ed. Detroit: U*X*L, 2007. Student Resource Center - Silver. Gale. Christopher Dock Mennonite High School. 19 May. 2010 <http://find.galegroup.com/srcx/infomark.do? &contentSet=GSRC &type=retrieve &tabID=T001 &prodId=SRC-2 &docId=EJ2644300851 &source=gale &srcprod=SRCC &userGroupName=pl2118 &version=1.0>.