The mean distance of the sun from the earth is $1.5 \times 10^8 \text{ km}$ (nearly). The time taken by the light to reach the earth from the sun is.....$\text{min}$

The principle of 'parallax' is used in the determination of distances of very distant stars. The baseline $AB$ is the line joining the Earth's two locations six months apart in its orbit around the Sun. That is,the baseline is about the diameter of the Earth's orbit $\approx 3 \times 10^{11} \; m$. However,even the nearest stars are so distant that with such a long baseline,they show parallax only of the order of $1''$ (second of arc) or so. $A$ parsec is a convenient unit of length on the astronomical scale. It is the distance of an object that will show a parallax of $1''$ (second of arc) from opposite ends of a baseline equal to the distance from the Earth to the Sun. How much is a parsec in terms of metres?

The magnitude of any physical quantity

What is accuracy in measurement? Accuracy depends on which factors?

Write the ratio of the maximum and minimum time observed in the universe.

Why is the parallax method not used to measure the distance of stars that are $100$ light-years away?