When an object passes in the course of another object’s shadow is when eclipses happen. Any kind of shadow consists of two parts. First is the umbra which is region of total shadow while the penumbra is the external region of partial shadow. Compared to the moon, the Earth’s shadow is very big. Since the shadow is very big this can cause a total lunar eclipse to last about 1 hour and 45 minutes. For example the moon passes through the penumbra; the observers on the moon will see a partially covered part of the sun. The observers on Earth on the second hand will see the moon partially dimmed hence calling this a partial lunar eclipse. There is a very unique and interesting effect that happens during a total lunar eclipse which is the moon turning into a copper red color. Although the Moon is in the Earth’s umbra the sunlight refracts or bends as it passes throughout the earth’s atmosphere. The bluer colors in the sunlight are removed by the dust particles thus making the moon look red since it will be the only colors that will reach the moon. The deepness of the red colors is determined by the amount of dust. Another fact is that the dust in the air is the reason on why the Sun looks redder during the sunset.
Write a paragraph on how can relate Eratosthenes’ work with the ideas with you learned in this chapter. The basic concepts of a circle can be related of that in Eratosthenes’ work. One example is the circumference of a circle which was used in measuring the circumference of the earth. Another is the secants of a circle which he used the sunlight as a secant to the earth. The points of intersection are the Alexandria and Syrene. The PAIC is a part of the 2nd term but Eratosthenes used the rays of the sun as the pair of parallel lines and angles coming from the shadows which is formed as the line that passes through the pair of parallel