'Albedo' is defined as:

The angle of maximum elongation for Venus is $47^\circ$. The distance of Venus from the Sun in $AU$ is .......

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?

$CO_2$ gas is found in which of the following pairs of planets?

If the axis of rotation of the earth were extended into space,then it would pass close to

Which of the following is not true about the total lunar eclipse?