TH THE E SU SUN N AND TH AND THE E EAR EARTH TH All Ab - - PowerPoint PPT Presentation
TH THE E SU SUN N AND TH AND THE E EAR EARTH TH All Ab About out Day y and Night ght Ex Explaining laining Day an y and d Nigh ght Ancient cultures explained day and night The Egyptian sun god, Ra, traveled across the sky
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■ Ancient cultures explained day and night – The Egyptian sun god, Ra, traveled across the sky each day – Ancient cultures did not understand
■ The Earth rotates on its axis ■ The Sun is stationary
for the Earth to make one complete rotation?
Earth rotates?
■ The rotation of the Earth causes day and night ■ Because of the Earth’s rotation: – The Sun rises on the eastern horizon – The Sun sets on the western horizon ■ During a 24 hour period: – The side of the Earth facing the Sun experiences daytime
■ Daytime: one side of the Earth is illuminated by the Sun
– The side of the Earth facing away from the Sun experiences night time
■ Night time: the side of the Earth facing away from the Sun is in darkness
■ YouTube video explaining day and night – https://www.youtube.com/watch?v=l0OCX3pBcJg
■ How was time measured in the past? – Observations of:
■ Day and night ■ Position of the Sun ■ Seasonal change
■ Can you explain what is happening in the two pictures – Hint: Notice the shadow of the woman in the picture ■ How is her shadow changing? ■ Why do you think her shadow is changing?
11:00 AM 4:00 PM
■ This is one design for a solar clock ■ How do you think the solar clock would be used to tell time during the day? – Hint: Look at the shadow – Hint: Would the shadow change during the day?
■ How do you think a sun clock would work? ■ Do you think that your shadow would change during the day? – Would the changes in your shadow relate to the time?