Answer:
Step-by-step explanation:
The author helps readers understand the method, scientists use to determine a spacecraft's distance from Earth as he says they send the signal to space with the speed of light. And according to them the time that light takes to reach space and come back is the distance between space and the earth.
He also says the same concept is used every day by people he takes the example of the distance of the grocery store from the house he says we a person can walk a mile in sat 20 mins n he takes around 30 mins to walk to the grocery store then by this he could calculate the distance between the grocery store and house.