In this fifth and final article on Our Amazing Moon we will examine how the moon’s orbital path and mass keeps the earth’s polar axis stable relative to the Sun, maintaining consistent seasons annually.
Gravity and Angular Momentum
In much the same way as the mass of the Moon tugs on the oceans of the Earth to regulate the global tides1, it also tugs on the surface mass of our planet to keep it oriented in a relatively tight rotational alignment.
Like the oceans of the Earth, the solid surface mass ‘lags’ along behind the Moon in its orbit, following the same path. This causes a ‘drag’ effect on the rest of the planet that acts in-line with the path of the Moon’s orbit about the Earth. Coupled with similar forces from the Sun these influences regulate the ‘wobble’ of the Earth’s polar axis in space to maintain a nearly perfect 23.5° tilt relative to its orbit in the equatorial plane.
Our local Moon, due to its close proximity and large relative mass to the Earth, applies enough force to our planet to impart a good deal of angular momentum2 in the direction of its spin. Since the Moon spends roughly equal time during its precession cycle3 north and south of Earth’s equator, the net effect of its motion is in alignment with the equator.
The Moon ‘tugs’ on the surface mass of our planet to keep it oriented in a relatively tight rotational alignment about its polar axis.
This becomes very important when we consider that, not only would the Earth have a tendency to ‘wobble’ off its axis due to the various gravitational forces it encounters during its orbit, but due to the gyroscopic effect of its own rotation as well.
Another means by which our Moon assists in stabilizing the rotation of the Earth about its axis is known as the gyroscopic effect. While there are a number of advanced mathematical formulas that explain the principles that govern gyroscopic physics, the best way to illustrate the gyroscopic effect is by simple example.
In Figure 1 above we can briefly observe the operation of a hand-held gyroscope. While we notice that the axis which passes through the center of the gyroscope is experiencing precession (rotation about the base upon which it is resting), it continues to remain stable within the spinning ring (i.e. no ‘wobble’)4.
This maintenance of our polar alignment in space independent of all other celestial bodies is what causes us to have regular seasons upon the earth.
The ‘Perfect’ Balance for Seasons
Because the Earth’s axis has a very specific tilt angle and maintains almost that exact angle throughout its entire orbit around the Sun, the angle at which sunlight (and therefore radiant heat) strikes the Earth changes throughout the year over the entire planet5.
The Earth follows an elliptical orbit about the Sun which also contributes to the seasonal changes as well. Primarily, this orbit brings the Earth closer to the Sun when the Southern Hemisphere is experiencing summer and the Northern Hemisphere is in winter. Likewise, the opposite is true when the Earth is farthest away from the Sun in its orbit. This tells us that, while our distance from the Sun within the range of our orbit certainly plays a role in temperature and climate, our angle relative to the approaching sunlight is a far more critical value. This is the reason why the constant maintenance of our Earth’s axial tilt is vitally important to the uniform annual progression of seasons globally.
The maintenance of our polar alignment in space independent of all other celestial bodies is what causes us to have regular seasons upon the earth.
Referring to Figure 2 below we see how the Earth is oriented relative to the Sun as the Northern Hemisphere is in each of the four seasons. This simple graphic demonstrates both the Earth’s angle and distance (not to scale) relative to the Sun. Since the Earth’s polar axis continues to point in the same direction in space as the Earth revolves around the Sun, the relative angle between the sun-facing side of the earth and the Sun is constantly changing.
“And God said, Let there be lights in the firmament of the heaven to divide the day from the night; and let them be for signs, and for seasons, and for days, and years: And let them be for lights in the firmament of the heaven to give light upon the earth: and it was so. And God made two great lights; the greater light to rule the day, and the lesser light to rule the night: he made the stars also.” -Genesis 1:14-16
The Word of God tells us that ‘signs’ and ‘seasons’ are among the very reasons that the Lord placed the Sun and Moon in the heavens. The Moon orbits the Earth approximately every 28 days, thus marking a regular seasonal timeclock in the sky day-by-day. As the Moon passes through each of its phases we can tell by which part of the current phase we are in how much time has passed since the beginning of the phase.6
Now we know that our Moon not only helps us to count the seasons, but it also helps to maintain our regular seasons as well. So the phrase ‘for seasons’ actually has at least a two-fold reference that we know of in the above passage from Genesis chapter 1.
Creation and Man
“So God created man in his own image, in the image of God created he him; male and female created he them. And God blessed them, and God said unto them, Be fruitful, and multiply, and replenish the earth, and subdue it: and have dominion over the fish of the sea, and over the fowl of the air, and over every living thing that moveth upon the earth.” -Genesis 1:27-28
The Lord God did not create man until after He had finished creating everything else in the entire universe. This fact as presented in Genesis chapter 1 reveals two wonderful relationships among man, his Creator, and God’s Creation:
- Since man was the last Creation of God, he (man) could take no credit for any of the work wrought by the Hand of the Lord God.
- Having completed His marvelous Creation, the Lord God was able to present it in completed and fully functional form to His grandest Creation – made in His own Image and Likeness (Gen. 1:26) and give him (man) dominion over it.
The ‘Our Amazing Moon’ Article Series has focused on just one of the countless Creations of God that has been designed for the specific purpose of supporting and sustaining mankind upon the Earth. This same God has given us His Only-begotten Son, Christ Jesus, so that all who call upon Him may have Everlasting Life, and freedom from the penalty of sin.
“He that believeth on the Son hath everlasting life: and he that believeth not the Son shall not see life; but the wrath of God abideth on him.” -John 3:36
In His Love,
Dr. Jack L. Burton
(1) NASA Planetary Fact Sheets and associated satellite data sheets.
(2) TheSky Astronomy Software © 1984-2000. Software Bisque, Inc.
(3) NOAA Ocean Service Education. Tides and Water Levels.
(4) NASA. Newton’s Laws of Motion.
(5) Dictionary.com. Gyroscope.
(6) Real World Physics Problems. Gyroscope Physics.
(7) Windows to the Universe. Earth’s Tilt is the Reason for the Seasons.
- Refer to the previous article in this series entitled: Our Amazing Moon IV: Lunar Mass & Tidal Regulation.
- In basic terms, the ‘conservation’ of angular momentum is the physical property of the Earth (or any spinning or rotating object) to continue spinning on the same axis at the same rate unless acted upon by an outside force.
- Refer to the third article in this series entitled: Our Amazing Moon III: Unique and Critical Orbit.
- All orbiting bodies experience orbital precession due to the gyroscopic effect of their spin about their own axis. Lunar orbital precession is discussed in the third article in this series entitled: Our Amazing Moon III: Unique and Critical Orbit. Likewise, the Earth also experiences orbital precession as it orbits about the Sun; however, this motion does not affect the 23.5° axial tilt of our planet relative to the ecliptic plane.
- Follow the link below and click on the image to view an illustration of the effect of the Earth’s axial tilt on the seasons annually:
- Follow the link below for more information on lunar phases and related information:
- All Bible quotes in this article are taken from the KJV.
- Bible passages in double quotes (“) appear exactly as found in the KJV.
- Bible passages in single quotes (‘) have been modified for emphasis or ease of reading only (such as capitalization of pronouns referring to God, bolded text, or modernized punctuation, etc.) without altering the actual wording of the text.
Disclaimer: While to the author’s knowledge all of the information cited in the referenced material related directly to the content of this article is correct and accurate, the author in no way endorses any of the cited references in their entirety – especially where the material contained therein is in direct contradiction with the Creation account given in the Word of God.