High-Q | סימולציה 12

26

סימולציה מס' 12

אנגלית – פרק שני

Text II (Questions 18-22)

The moon has two types of motion that affect the way we see it from Earth. It revolves around the Earth, and rotates on its own axis. The time for one rotation is the same as for one revolution, 29 ½ Earth days. Because the moon orbits the Earth in the same time that it rotates, the same side of the moon always faces the Earth. This lockstep motion is no accident. Earth's gravity created a bulge in the moon's mass when the moon was formed, and then gravitational attraction between the 5 Earth and the extra mass in the bulge kept the moon from rotating freely. The moon cycles through a progression of phases as it orbits. A phase is the appearance of the lighted portion of the moon, which depends on its relation to both the Earth and the sun. Visualize the Earth moving around the sun while the moon is orbiting the Earth, both orbits being pretty much, but not quite, in the same plane. When the moon is almost exactly between the Earth and the 10 sun, we see the side that is faced away from the sun - the dark side. This is the new moon. A few days later, as the moon continues in its orbit, we see a thin sliver called a crescent. Seven days after a new moon, half the face we see is illuminated - the half moon. Confusingly, it is also called the first-quarter moon because it comes one-fourth of the way through the cycle of phases. 15 One week later, the moon is on the opposite side of the Earth from the sun, so its entire face is sunlit - a full moon. On occasions when the moon is on the opposite side and the sun, Earth and moon form a straight line, a lunar eclipse occurs. Another week and we again view a half moon, this time called the third-quarter moon, and finally, just 29 ½ days from the last new moon, another new moon. 20

High Q Global ©

Made with FlippingBook Online newsletter creator