ASTR PTYS 206 Dr. Kortenkamp September 3, 2013 HW2 _ Aristarchus

The size of the Sun compared to the size of the Moon is a big difference. The

Sun and the Moon look to be the same size, but it is deceiving because they are nowhere close to being the same size. The Sun is 1,392,000 kilometers across and the moon is 1,737 kilometers. So about ten moons can span across the width of the Sun. The Moon and the Sun are at two difference distances from the Earth. The Moon is about 384,400 kilometers from the Earth and the Sun is 149,600,000 kilometers from the Earth. The Earth is smaller then the Sun, but larger then the Moon.

In the picture below, the cacti look like they are all the same size. When you are standing right next to the cacti that are father way they are actually all different sizes. It is like looking at the Sun and the Moon; they look the same size when looking at them but in all reality they are two completely different sizes. A famous Greek astronomer, Aristarchus,

concluded that the Sun is way bigger then the Moon because of the shadows of the Earth. With this evidence, the Earth must revolve around the Sun. He figured out how to measure the distances from the Earth to the Sun and the Moon. He concluded that the radius and

Sheedy distance is similar because of the relationship of the size. Aristarchus figured out when there is a half Moon the angle from the Earth to the Moon to the Sun is about 90 degrees. Assuming all right triangles are the similar in angels, he was able to calculate the distance through the equation: Radius of sun/ radius of moon = diameter of sun/ diameter of moon R sun / R moon = 1 AU / 0.0023 AU =435.732 R moon x R sun / r moon = 435 moon Radius of Sun = 435 Radius of the Moon This equation proves that the Sun is that much farther way from the Earth then the Moon is.

Sheedy

Works Cited http://www.astro.cornell.edu/academics/courses/astro201/aristarchus.htm

http://eofdreams.com/photo/cactus/01/