Chapter 5, Problem 23Q

To determine

To identify: Whether Earth is closer to earth in January or July.

Explanation of Solution

Introduction :

According to Kepler law of planetary motion a satellite sweeps equal area in equal interval of time.

During January earth becomes more closer to the sun as compared to July, so to sweep equal area it has to move a greater arc length along its orbit. That is why earth moves faster in January on its orbit as compared to July.

Conclusion :

Therefore, during January earth is closer to sun and hence moves fast.