Type:

E-book, Lesson Plan

Description:

This lesson is part of the Athabasca University Astronomy 230: Northern Lights, Northern Skies course. In this lesson, you will learn how to identify what causes days and years, how to describe the structure and reasons for time zones, and how to describe what causes the seasons.

Subjects:

  • Science > General
  • Science > Astronomy

Education Levels:

  • Grade 11
  • Grade 12
  • Higher Education
  • Graduate
  • Undergraduate-Upper Division
  • Undergraduate-Lower Division
  • Other

Keywords:

astronomy earth pole axis orbit solstice equinox altitude azimuth zenith declination ascension constellation celestial sphere Polaris circumpolar motion

Language:

English

Access Privileges:

Members

License Deed:

Creative Commons Attribution 3.0

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None
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In position 1, the northern hemisphere is tilted away from the Sun, receiving less sunlight. This is our winter season.

In position 3, the northern hemisphere is tilted toward the Sun, resulting in warmer weather in the summer.

Positions 2 and 4 show sunlight hitting the northern and southern hemispheres equally. This is our spring and fall, respectively.



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In between these times the Sun’s light is shining directly down on the Earth between the two Tropics, moving to the north and south. On September 23rd, the Sun is directly over the equator, moving to the south, and this day is called the Autumnal, or Fall Equinox. On March 21st, the Sun is directly over the equator again, but moving towards the north, on the Vernal, or Spring Equinox.


soltices.jpg
The positions of the earth throughout the year.

Canadian Contributions

Perhaps the most noticeable effects of astronomy in Canada are the seasons: few other countries can boast an average temperature change of about -30?C to 30?C throughout the course of the year!

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