Movement in the Solar System

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Movement in the Solar System
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Can you explain ?

1. Why do day and night happen on Earth ?
2. What is a year ?
3. What is a month ?

3
Why do day and night happen ?

• The Earth continually spins around on its axis.
• On the side which is facing the sun it is
  day-time.
• On the side which is facing away from the sun it
  is night-time.

day
night
Earths axis
4
What is a year ?

• A year is the time it takes for the Earth to
  orbit the sun once.
• This is 365 and ¼ days.
• We add an extra day every fourth year to deal
  with the ¼ days. This is a leap year.

5
What is a month ?

• There are a number of meanings for the word
  month.
• Roughly, it is the time taken for the moon to
  orbit the Earth once ( 28 - 30 days ).