What are the approximate sizes of the observable universe and an atomic nucleus?

What are inferior planets,and what is meant by the elongation of a planet?

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

The magnitudes of two stars $A$ and $B$ are $2.5$ and $-5$ respectively. The brightness ratio of $\frac{B}{A}$ is

What is a Red Giant?

Assuming that the dimmest visible star to the naked eye has a magnitude of about $6$. The brightness of planet Venus (magnitude = $-4$) with respect to this star is ........ times brighter.