Yesterday, March 20, 2021, the Sun was directly over the equator, and that brought in the spring (vernal) equinox in the Northern Hemisphere. Of course, it was the autumn equinox for those south of the equator. That means if you want to know what direction is due east, all you would need to do is watch the Sun come up, and due west was where the Sun went down. From now until June 20, the Sun will be moving farther north. We call that day the summer solstice. Where we live in the mid-Northern Hemisphere, the Sun will rise and set about 33 degrees north of due east and west on that day. Why do we need to have the Sun moving north and south in our sky anyway? Why can’t we have the equinox all year?
If the Sun continually stayed directly above the equator, life on Earth would be more difficult. Areas near the equator would be much too hot, and regions far from the equator would be much too cold. There would be two narrow “Goldilocks” areas in between that would be hospitable for life. Plants need a respite from the growing season to prepare for the next growth cycle. Animal life depends on the seasons for reproduction and growth. We would miss the beauty of the changing seasons. So having the equinox all year would not be a good idea. Then why does our planet have this variation in the direction of the Sun?
Earth’s axis tilts 23.5 degrees, and as our planet makes its annual journey around the Sun, the tilt varies toward or away from the Sun. At our summer solstice in June, the inclination is toward the Sun, and at the winter solstice, the axis tilts away from the Sun. That makes the Sun appear to move from 23.5 degrees north of the equator to 23.5 degrees south. At the equinox, for a moment, the Sun is precisely over the equator. The next question is, does this just happen to be a lucky accident?
Since this is just one more factor that makes Earth suitable for advanced life, how could we be so lucky? We have discussed before the many factors that must be just right for life to exist. This is one more, and we don’t think it’s an accident. We believe it’s another evidence of a wise Designer. God gave us seasons for a purpose (Genesis 1:14).
— Roland Earnst © 2021