How much time would it take to go up to the moon and back

What is hidden during a lunar eclipse? isn't the moon hidden?

What property is a characteristic of a substance that can be observed and does not change the identity of the substance

Unpolarized light of intensity i_0=750w/m^2 is incident upon two polarizers. after passing through both polarizers the intensity is i_2=280w/m^2. (a) what is the intensity of the light after it passes through the first polarizer in w/m^2? (b) write an equation for the angle between the polarizers in terms of the initial (i_0) and final (i_2) intensities. (c) find the angle between the polarizers in degrees.