The tail of a comet points

The number of stars in our solar system is

$A$ total solar eclipse is observed from the Earth. At the same time,an observer on the Moon views the Earth. She is most likely to see ($E$ denotes the Earth):

The rate of solar energy incident on a unit area of the Earth is approximately ....... $(kW/m^2)$.

Suppose the Sun was located at the position occupied by the nearest star,say,Alpha Centauri,$4$ light-years away. By what factor would the solar radiation received per second per unit area decrease?

Who was the first Indian astronaut to travel into space?