Universe – Eclipses


 
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The Universe – Solar and Lunar Eclipses

Directions: Using a small styrofoam ball, a pencil, a lamp, and your head, let's try to understand how eclipses work.

  What is a lunar eclipse? 
  What is a solar eclipse? 

We can understand eclipses by creating models of the Sun, Moon, and Earth.

1.  Place a lamp at the front of the room and turn it on. (Remove the lampshade, please.)
2.  Stick a pencil into your styrofoam ball so you can easily hold it.
3.  Turn off the lights.
4.  Stop playing around.
5.  Face the lamp, holding your pencil/ball at arm's length. The lamp represents our Sun, the
 styrofoam ball the Moon, and your head the Earth.

Move the “moon” around your head to model its revolution around the Earth. Position the moon so it's directly opposite the Sun, with your head casting a shadow on it. When the Moon passes into the Earth's shadow, we have a lunar eclipse.

  What is the area of total lunar eclipse called? 
  What is the area of partial lunar eclipse called? 

Move the Moon around the your head until it completely blocks your view of the Sun/lamp. When the Moon is positioned between the Earth and the Sun, a solar eclipse occurs.

Watch the sizes of the shadows. Look at a friend's face during the solar eclipse. How big is the shadow that falls on his/her face? _______________

Do more people see a solar or a lunar eclipse? ____________________

Now that you understand what causes an eclipse, think about lunar phases and how often there should be solar and lunar eclipses. Experiment with your models. How long it takes for the Moon to orbit the Earth? _______________ What phase is the Moon in during a solar eclipse? ___________________ During a lunar eclipse? _____________________

How many times a year do those two things happen? __________________

If the Moon were orbiting in the exact plane as the Earth and the Sun, we would have a lunar and a solar eclipse once a month each. However, the Moon's orbit is tilted to the plane of the ecliptic. You can demonstrate this by holding a hula-hoop around the lamp, and a smaller embroidery hoop within the hula-hoop, tangent to it, and slightly askew to it. The embroidery hoop represents the Moon's (monthly) path around the Earth, the hula-hoop the Earth's (yearly) path around the sun. Where do the Moon and Sun have to be to produce an eclipse?

How many times a year do the Sun and the Moon reach those positions? __________________

Any questions?

 
 

 
 
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