This is because the Earth is not spinning upright. The Earth is slightly tilted or leaning on its side by Sunlight falls only on one side of the Earth. This side of the planet will be experiencing daylight. Because the Earth is rotating, the opposite side of the Earth away from the Sun will be experiencing night.
After some time, the part of the Earth experiencing daylight will experience night. Rotation of the Earth causes night and day to alternate. Different places in the Earth experiences different lengths of night and day. The 12 hours of day and 12 hours of night happens only in places near the equator, for example the Philippines. Arctic and Antarctic experience polar day when the Sun stays above the horizon for more than 24 hours and polar night when night lasts for more than 24 hours.
The styrofoam ball represents the Earth. Draw the outlines of the continents on the styrofoam using a pencil. You will use the globe model shown by your teacher or the map of the globe on the projector as drawing guides. The drawing does not need to be detailed.
These observations can be made during the day as well as at night. They should then be guided to develop their own questions to research and explore. In this way the research is more directed and not simply a fact finding exercise.
Opportunities to make models and to manipulate the models to help students explain their ideas should be provided. The manipulation of models also assists students to view the motion of the sun, Earth and the moon from a new perspective of an observer of the whole system as opposed to their usual perspective as an observer on a very small region on the surface of the Earth.
This can be used as a starting point to challenge existing ideas and to explore new ideas. Student drawings and their associated explanations of the motion of the Earth and sun can be used to challenge their existing ideas and to help them to reflect on their understanding. To help students move from their usual perspective of an observer on a small part of the Earth to an observer outside the Earth simulation computer programs or websites can be used. Students could present posters or diagrams suitable for display on an overhead or data projector to help them to interpret and share new perspectives with their peers.
Students could also explore indigenous interpretations of the motion of the sun and Earth. Time Zone by Mandy Barrow. Science index. Sunrise and Sunset project. The Earth takes 24 hours to make one complete turn. Why do we have day and night? How long does it take the Earth to turn around? Before electricity, people experienced bright, full-spectrum days of sunlight and dark nights.
We slept in a different way than we do now. The dark lasted about twelve hours and during this time people slept for eight or nine hours in two separate bouts, and were awake, but in the dark, for another three or four hours. Everything changed when electric lighting was invented in the latter part of the 19th century.
Since then there has been an ever increasing assault on dark. Outdoor environments are relentlessly lit, and more and more people use computer tablets and smart phones at all hours, bathing their faces in bright blue light at times of day when they should be transitioning to nighttime physiology.
When people get away from the city and its artificial light to go camping, they often notice a marked improvement in their sleep. A recent study has verified this effect. Today, most of us get too little light during the day and too much at night for our circadian rhythm to function at its best. It is the rare person who sleeps in a completely dark bedroom, and many people get very little sunlight because they work inside all day long.
What can you do for your circadian health? Get bright, blue light in the morning preferably from the Sun , and use dim, longer wavelength light more yellow and red like incandescent in the evening. And sleep in the dark.
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