The Earth and the Solar System

Science — First Preparatory

Applications and examples from life

Comparison aspect	Main idea	Keywords
Day and night model	we fix a small ball on a stick and switch on a lamp that represents the Sun in a dark room. We then turn the ball slowly on its axis. The side facing the lamp represents day and the other side represents night	smallballstickswitch
Time for sunlight to arrive	the average distance from the Sun to the Earth is about 1.5 × 10¹¹ m, and the speed of light is 3 × 10⁸ m/s. So the time = 1.5 × 10¹¹ ÷ 3 × 10⁸ = 500 s, which is about 8 minutes and 20 seconds.	averagedistanceEarth1011
Days in a year	if a year is 365.25 days then in 4 years we have 4 × 365.25 = 1461 days which equals 365 × 4 + 1. So the fourth year is a leap year	thenyears1461equals

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