Tuesday, August 18, 2015

Adapting to Seasons

“Snow birds” describes a population of US northern climate residents who  take refuge from cold winters by migrating to the south, perhaps Florida or Arizona, during the harshest winter months. In the world of wildlife some animals, notably birds and a few insects, also journey to a warmer wintering spot in the southern US, Central America, or even South America. The “snow bird” phenomenon would not occur without the existence of Earth’s axis tilt. The slanted axis results in fascinating meteorological and astronomical variety. The case could be made that Earth would be an arguably less interesting planet without the tilt of its axis.

It is well known that Earth’s axis of rotation is slanted 23.5º from an orientation perpendicular to the plane of Earth’s orbit. This is known as axial tilt or obliquity. The axial tilt has been very constant—close to 23.5º, varying only slightly on a cycle of 41,000 years. The plane of Earth’s orbit, from which axial tilt is measured, has been virtually the same for millions of years. Earth’s motion of revolution locates the plane of  our planet’s orbit. All Solar System planets orbit in a plane similar to Earth. Their collective orbits appear like a flattened disc surrounding  the sun.

In the days when the Old Testament was written, the scientific details mentioned above were not known. Astronomical observations were based on visual glory and predictability and the ability of heavenly bodies to inspire worship of the Creator. One of the most famous passages comes from Genesis 8:22 in a promise made to Noah. “As long as the earth endures, seedtime and harvest, cold and heat, summer and winter, day and night will never cease” (NIV). This verse, while lacking astronomical specifics, accurately describes the effects of rotation and revolution, outcomes of axial tilt, the wondrous phenomena of plant growth and harvest cycles, and the glorious variety of environmental conditions provided for the thriving of man and all created living things.

Earth’s moon is an unusual satellite in a planetary system. It is unusually large among the Soar System planets. Scientists have determined that the moon acts to stabilize the axial tilt of Earth and provides not only the presence of seasons on our planet, but also their enduring consistency over extended geological time frames. Three of four points in the Genesis 8:22 reference are related to seasons directly or indirectly. Without Earth’s axis tilt there would be no seasons at all.

In our imagination we could speculate on the effect of reducing Earth’s axial tilt to 0º. There would be adjustments in agriculture. Some cold weather crops would not thrive. Grain crops which thrive in temperate climates during warm seasons would no longer thrive. Primarily, Earth’s food supply for seven billion souls would be devastated. Natalie Wolchover writing on the LiveScience website echoes the statements of many analysts: “Without Earth’s tilt, humanity would be in a sorry state.” Genesis 8:22 implies the importance of “seedtime and harvest, cold and heat, summer and winter” for the benefit of humanity. We invite readers to research detail on their own concerning the importance of seasons.

Here is a 2011 post from our blog archives: