Why does Mars exhibit retrograde motion in the sky? Mars orbits the Sun in the opposite direction as the Earth.

As Mars overtakes and passes the Earth in its orbit, Mars appears to move backwards.

As the Earth overtakes and passes Mars in its orbit, Mars then appears to move backwards.

When Mars and the Earth are on opposite sides of the Sun, it can no longer be seen at night.

What is the reason of this question?

When a vertical beam of light passes through a transparent medium, the rate at which its intensity i decreases is proportional to i(t), where t represents the thickness of the medium (in feet). in clear seawater, the intensity 3 feet below the surface is 25% of the initial intensity i0 of the incident beam. what is the intensity of the beam "10" feet below the surface? (give your answer in terms of i0. round any constants or coefficients to five decimal places.)