A Solar Eclipse occurs when the moon passes in front of the sun, and blocking out all or some of the light from the point the moon covers. The point on Earth that is darkened by the eclipse is called the preumbra or umbra. The preumbra is along the outer skirts of the point that is darkened, it is the area that is only partially darkened. The umbra is the area of the eclipse that is totally darkened. Another type of elcipse we sometimes have is called an annular eclipse. An annular eclipse is when the moon is farther away from earth, and cannot completely block out the sun.
Solar eclipses happen when the moon's shadow crosses the face of the earth. The shadow usually moves at a speed of about 2,000 miles per hour. There are three types of eclipses: The total eclipse, the annular eclipse, and a partial eclipse. In the event of a total eclipse, the dark moon appears on the western edge of the sun and slowly moves across the sun. The sky remains blue, but darkens and some of the bright stars and planets may become visible for a short while. Around the area where there is a total eclipse, or an annular eclipse of the sun, there is always a much larger area where there is a partial eclipse. This area is the moon's prenumbra.
When Aristarchus looked at a solar eclipse, he noticed this model
He noticed that the triangle between the Earth and the moon, was a similar triangle to the triangle from the Earth to the sun. He used this ratio:
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By Jaime, Jennifer, and Joey