When a satellite moves around the earth in a certain orbit,the quantity which remains constant is:

If the angular momentum of a planet of mass $m$,moving around the Sun in a circular orbit is $L$,about the center of the Sun,its areal velocity is

$A$ planet moving around the Sun sweeps out an area $A_{1}$ in $2$ days,$A_{2}$ in $3$ days,and $A_{3}$ in $6$ days. Then,the relation between $A_{1}, A_{2}$,and $A_{3}$ is

$Assertion$ : For the planets orbiting around the sun,angular speed,linear speed and $K.E.$ change with time,but angular momentum remains constant.
$Reason$ : No torque is acting on the rotating planet. So its angular momentum is constant.

The distance of a planet from the sun is $5$ times the distance between the earth and the sun. The time period of the planet is

Give the contribution of Tycho Brahe on planetary motion.