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Planets and stars are gyroscopes

Imagine that you have a bicycle wheel with excellent bearings mounted on an extended, two-foot axle. Suppose also that the tire is completely filled with lead, then balanced and spun up to about 1000 rpm. If you were to hold both ends of the axle while the wheel were spinning, you would discover that you could not turn the axle to point in a different direction. Although you could easily "slide" the axle through the air keeping it pointed in the same direction, you would be completely unable to change the direction in which the spin axis points!

Planets and stars are gyroscopes

 

 

Here’s a second experiment. Attach a top within a hoop. Now attach that hoop to rotate within a second hoop as in the picture above, so that the spin axes of the two hoops are at right angles. If the friction is negligible and the top spins at a high speed, the top’s axle will appear to slowly rotate end over end through a complete circle in 24 hours. Although it is the top that appears to rotate, the direction of the top’s spin axis in space is fixed relative to the stars. It is the Earth, carrying the room that the top is in with it, that is actually rotating around the top!!

How can this be? Well, Newton’s first law states that a body in uniform motion will tend to stay in motion unless acted upon by an outside force. This tendency of moving bodies to continue moving or to stay at rest is called "inertia." And spinning bodies—the bicycle wheel, the top, and the Earth—all have "rotational inertia:" the tendency of a spinning body’s spin axis to remain pointed in the same direction in space. As long as a spinning body is not acted upon by an outside force its spin axis will remain forever pointed in the same direction in space relative to the stars! This is how gyroscopes form inertial guidance systems for planes, submarines and spacecraft. These vehicles constantly refer to a gyroscope’s fixed and rigid orientation in space in order to navigate and maintain their bearings.

The spin of a planet or a star increases as it condenses from a cloud of gas and debris, just as a skater increases her spin by pulling in her arms. And since all spinning bodies have rotational inertia, the Earth’s spin axis always points in the same direction in space, the North star as it orbits the Sun. Since the Earth’s equator is always perpendicular to its axis which ifs directionally fixed in space, the Earth’s equatorial plane is also directionally fixed* in space as the Earth orbits the Sun. And since the Earth’s orbital plane (the ecliptic) is also directionally fixed in space, these two fixed planes intersect in a line that is also directionally fixed* in space, the line of the equinoxes pointing to 0° Aries and 0° Libra.

Because the Sun and the Moon pull unevenly on the Earth (since the Earth is not a perfect sphere but bulges at its equator), the Earth’s spin axis does NOT always point exactly in the same direction in space (at or near the North star). Rather the direction of the Earth's spin axis paints a small circle on the celestial sphere which is completed every 26,000 years. This motion produces what is known as the precession of the equinoxes, in which this discussion is continued.

This Planets and stars are gyroscopes page and much of this 600-page website are excerpted from the personalized Fine Art Book You and the Universe.

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© Carl Woebcke: Planets and Stars are Gyroscopes, 1991-2016. All rights reserved.