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FN - Reason for the Seasons
CN “Earth’s Motion”
pg. 25-26
The Sun
- Nearest star to Earth
- Has a diameter 100 times greater than Earth’s
- Core reaches temperatures over 15,000,000℃
- Surface reaches temps of 5,500℃
Earth’s orbit
The Earth orbits around the Sun
- One complete revolution every 365.24 days due to the
Sun’s gravitational pull
As Earth orbits around the Sun, it rotates (spins on its rotational
axis)
- One complete rotation every 24 hours
Earth’s Orbit
Earth’s orbit is an ellipse (an
elongated closed curve)
The Sun is not centered in the
ellipse causing the distance
between the Sun and the Earth
to be different depending on
the time of the year.
Shape and Tilt of Earth
Earth’s surface is curved, meaning
that different parts of the Earth’s
surface receive different amounts of
the Sun’s energy
Earth is tilted 23.5 degrees off center
Reason for the Seasons
The tilt of the Earth, combined with Earth’s motion around the sun
causes the seasons to change.
- The hemisphere tilted toward the Sun receives more daylight
hours than the hemisphere tilted away from the Sun. THIS
IS SUMMER!
- The hemisphere tilted away from the Sun receives less hours
than the hemisphere tilted toward the Sun. THIS IS WINTER!
Reason for the Seasons
Solstice
- 2 times where Earth is EXTREMELY TILTED.
- June (summer) solstice is June 20/21 in the Northern
Hemisphere
- December (winter) solstice is Dec 21/22 in the
Northern Hemisphere
Equinox
- 2 times where Earth’s rotation axis
is not tilted!
- March (spring) equinox is March
20/21
- September (fall) equinox is Sept
22/23