Sun and earth

Timelapse photo taken over period of five hours, on the longest day of the year, showing multiple suns
Timelapse photo taken over period of five hours, on the longest day of the year (Photo: Wayne Papps)

Students can experiment to discover why the curvature of the earth causes the seasons and why such extreme seasons are experienced in Antarctica.

Antarctica receives 24 hours of daylight when it is tilted towards the sun (21 December) and 24 hours of darkness or near-darkness when it is tilted away from the sun (21 June). The live video views from Davis, Casey and Mawson provide graphic illustrations of this when observed over six months or more.

  • Using a globe of the world and a torch or an overhead projector, demonstrate that the earth has a light side and a shadow side, which correspond to day and night.
  • Students can experiment to discover why the curvature of the earth causes the seasons and why such an extreme in seasons is experienced in Antarctica.
  • As the sun rises at the south pole, it sets at the north pole. Take a look at Tromso, Norway (69° 42' N, 19° 00' E) in the Arctic and compare this with live web cam views of an Antarctic station (links above).
  • Students can research how many hours of daylight they receive where they live in the months of June, September, December and March. They should then compare this to an Antarctic station. See the Bureau of Meteorology's station links and graph the results.
  • Well worth a look is the Exploratorium's Earth and Moon Viewer. Students can view either a map of the earth showing day and night regions in real time or view the earth from the sun, the moon or the night side of the earth, above any location on the planet from a satellite in the earth’s orbit.

When the sun is low in the sky, its rays must heat more atmosphere and a greater area of ground than when it is high in the sky. That is one of the reasons it is always hot in the tropics and cold in Antarctica, and why winter is colder than summer.

  • To demonstrate the effect of the angle of the sun's rays on temperature, students can fill two open boxes with identical amounts of soil, placing one so that the sun shines directly into it, and the other so that the sun's rays strike it at a low angle. A thermometer in each box will record the relative temperatures after an hour, and demonstrate the difference in heat energy.
  • Students can also study the effect of the Antarctic ice sheet and sea ice on the absorption of solar energy. This ice reflects about 85% of the solar radiation back into the atmosphere, whereas in a tropical rainforest only around 12% is reflected.
  • Check out the Center for Educational Resources (CERES) Project's classroom-ready activities, especially Investigating the Dynamic Martian Polar Caps. In this activity, students download NASA Hubble Space Telescope images of the polar ice caps on Mars in summer and winter. Using image processing techniques, students can measure and compare various images of the changing Martian and earth polar ice caps.
This page was last modified on July 3, 2014.