Later, as the months wear on, a series of additional messages arrive from Gerry -- always delivered in the most remarkable and surprising of ways. With each new message comes a new adventure, and each letter signs off in the same familiar way: P.S. I love you..
For a person standing at sea level, however, the horizon is only about 3 miles away. Lets do the calculations. The figure below shows an observer whose eyes are a distance E above sea level. A straight line drawn from the observers eyes tangent to the seas surface touches it at the distance d1, which is the distance to the horizon. If R is the radius of the earth, then, to first order in E/R, it is easy to show that.
Now that weâre thinking about horizons, hereâs another cool thing to think about. The horizon is three miles away on earth. But elsewhere in the solar system itâs closer or farther, depending on the size of the body youâre standing on! Take the moon. The moon is two thousand, one hundred and sixty miles in diameter, only about one quarter the size of the earth. So the curvature at its surface is much more noticeable, and the horizon is much closer. Itâs only about 1.5 miles away.