Download K to 12 Science Grade 7 Learners Material - Module PDF

TitleK to 12 Science Grade 7 Learners Material - Module
File Size11.4 MB
Total Pages278
Document Text Contents
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269


Focus your attention on the shadow of the Earth in Figure 10. The shadow is
wider than that of the Moon. It also has an umbra and a penumbra. Which part of the
Earth’s shadow falls on the Moon? Is the Moon always found within the umbra?


The appearance of the Moon is dependent on its location in the Earth’s

shadow. When the entire Moon is within the umbra, it will look totally dark. At this
time you will observe a total lunar eclipse. But when the Moon passes only through a
part of the umbra, a partial lunar eclipse will be observed. A part of the Moon will look
dark while the rest will be lighter.


In earlier grades, you learned that it takes about one month for the Moon to
complete its trip around the Earth. If that is the case, then we should be observing
monthly eclipses. In reality, eclipses do not occur every month. There are only about
three solar eclipses and three lunar eclipses in a year. What could be the reason for
this?

The answer lies in the orbit of the Moon. Look at the orbit of the Earth and the
Moon in Figures 6 and 7. Do their orbits have the same orientations? As you can see
the Moon’s orbit is slightly inclined. The orbit is tilted by 50 from the plane of the orbit
of the Earth. As the moon moves around the Earth, it is sometimes higher or lower
than the Earth. In these situations, the shadow of the Moon does not hit the surface
of the Earth. Thus, no eclipses will occur. Eclipses only happen when the Moon
aligns with the Sun and Earth.


Facts, Myths, and Superstitions


Some people believe that a sudden darkening during the day (solar eclipse)

brings bad luck. Others say that it is also bad luck when the Moon turns dark during
a Full Moon (lunar eclipse).


Do you think these beliefs regarding eclipses are true? Let us find that out in

the next activity.



Activity 4
Does a Bakunawa cause eclipses?


Objective


When you finish this activity, you should be able to evaluate some beliefs about
eclipses.


What to do


1. Collect some beliefs about eclipses. You may ask older people in your family or

in the community or, you may read on some of these beliefs.

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