What is the accuracy of an atomic clock?

When the planet Jupiter is at a distance of $824.7$ million kilometers from the Earth,its angular diameter is measured to be $35.72''$ of arc. Calculate the diameter of Jupiter.

The angle of $1^{\prime}$ (minute of arc) in radian is nearly equal to

The difference between the length of a mean solar day and a sidereal day is approximately .......... minutes.

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

$A$ $LASER$ is a source of very intense,monochromatic,and unidirectional beam of light. These properties of a laser light can be exploited to measure long distances. The distance of the Moon from the Earth has been already determined very precisely using a laser as a source of light. $A$ laser light beamed at the Moon takes $2.56 \; s$ to return after reflection at the Moon's surface. How much is the radius of the lunar orbit around the Earth?