UNIT 1.- The Earth in the Universe
 
 The Solar System
 
    The Sun
     Mercury
     Venus
     Earth
     Mars
     Jupiter
     Saturn
     Uranus
     Neptune
     Pluto
     Ceres
     Moon
     Asteroids
     Comets
The Moon
It's the earth's only natural satellite It is 1/6 the size of the Earth, and its rotation takes the same time to complete an orbit around the Earth. Because that, the Moon always shows the same face to us. This face is covered by deep pits, commonly known as craters, that are the most numerous features of the moon's surface. The smaller craters were formed when meteoroids (solid objects traveling through space) collided with the moon. Scientists estimate that the moon has half a million craters that are more than one Km. wide. These huge pits were more than likely caused by larger bodies such as comets or asteroids.
 

The Moon presents phases. It takes the Moon one month to travel one time around the Earth passing through a complete cycle of its phases. In ancient times, before calendars were used, people looked at the phases of the Moon to measure weeks and months. They knew that four weeks passed between one full Moon and the next.Sometimes, as the moon circles the Earth, it passes directly between the Earth and the Sun. This causes a solar eclipse, which blocks our view of the Sun for a short while. Another type of eclipse is a lunar eclipse. This occurs when the Earth passes directly between the Sun and the Moon, briefly blocking out the Moon.

   
 

 
 Images
   

Phases Geometry
 

July 1969, the Man on the Moon