Write a short one page or less essay on a story that you hav

Write a short (one page or less) essay on a story that you have come across in which the earth is invaded by beings from another world. Indicate the source for your story as well as the invaders\' planet of origin. What was the ultimate fate of the invaders? Bippose that Eratosthenes had measured an angle of 6 degrees difference between the sun\'s rays at Alexandria and those at Seyene. What value would he have obtained for the earth\'s circumference and radius? Assume that the Bstancc between Alexandria and Seyene is equal to 800 km. The apparent brightness of the sun as seen from a binary asteroid is 400 watts/square meter, If the larger asteroid (Asteroid A) has an albedo of 0.6. what amount of brightness in watts/square meter does Asteroid A reflect back into space? If the smaller asteroid (Asteroid B) is observed to reflect 50 watts/square meter back into space, what is the albedo of Asteroid B?

Solution

2. Surface gravity = G M / R^2

= (6.67 x 10^-11 x 1.2 x 10^22 ) / (1.15 x 10^6)^2

= 0.6 m/s^2

ratio = 0.6 / 9.8 = 0.062 times of earth gravity

3. MEan Density = mass/ volume

    = M / (4 pi R^3 / 3) = (3 x 1.2 x 10^22 ) / (4 x pi x (1.15 x 10^6)^3)

= 1883.6 kg/m^3

For density to be 1000 kg/m^2 ,

that means radius have to be more.