[Box on page 22]

“The special conditions on earth resulting from its ideal size, element composition, and nearly circular orbit at a perfect distance from a long-lived star, the sun, made possible the accumulation of water on the earth’s surface.” (Integrated Principles of Zoology, 7th edition) Life on earth could not have appeared without water.

Earth’s Ideal Features

Our existence requires precision in other respects as well. Consider the earth’s measurements and its position relative to the rest of our solar system. The Bible book of Job contains these humbling questions: “Where did you happen to be when I founded the earth? . . . Who set its measurements, in case you know?” (Job 38:4, 5) As never before, those questions beg for answers. Why? Because of the amazing things that have been discovered about our earth—including its size and its position in our solar system.

No planet like earth has been found elsewhere in the universe. True, some scientists point to indirect evidence that certain stars have orbiting them objects that are hundreds of times larger than the earth. Our earth, though, is just the right size for our existence. In what sense? If earth were slightly larger, its gravity would be stronger and hydrogen, a light gas, would collect, being unable to escape the earth’s gravity. Thus, the atmosphere would be inhospitable to life. On the other hand, if our earth were slightly smaller, life-sustaining oxygen would escape and surface water would evaporate. In either case, we could not live.

The earth is also at an ideal distance from the sun, a factor vital for life to thrive. Astronomer John Barrow and mathematician Frank Tipler studied “the ratio of the Earth’s radius and distance from the Sun.” They concluded that human life would not exist “were this ratio slightly different from what it is observed to be.” Professor David L. Block notes: “Calculations show that had the earth been situated only 5 per cent closer to the sun, a runaway greenhouse effect [overheating of the earth] would have occurred about 4 000 million years ago. If, on the other hand, the earth were placed only 1 per cent further from the sun, runaway glaciation [huge sheets of ice covering much of the globe] would have occurred some 2 000 million years ago.”—Our Universe: Accident or Design?

To the above precision, you can add the fact that the earth rotates on its axis once a day, the right speed to produce moderate temperatures. Venus takes 243 days to rotate. Just think if the earth took as long! We could not survive the extreme temperatures resulting from such long days and nights.

Another vital detail is our earth’s path around the sun. Comets have a wide elliptic path. Thankfully, this is not so with the earth. Its orbit is almost circular. Again, this prevents us from experiencing death-dealing extremes of temperature.