The Sun's Gravitational Pull: How Strong It Is and How Far It Reaches

If the Sun's gravity ever stopped acting on the Earth, our planet would hurtle out of the solar system — just like a pebble released from a slingshot. Suppose for a moment that this actually happened. Let us see what would then become of our planet and of all of us, the inhabitants of the Earth.

What happens as the Earth moves away from the Sun?

As the Earth receded from the Sun to roughly the distance of the planet Uranus, we would already feel a marked decrease in light and in the life-giving influence of the solar rays. Then, with greater distance, the Sun would appear to us as nothing more than a bright star that gives little warmth. After some time we would see the Sun as a tiny, barely noticeable, faintly twinkling little star, and at last lose it from view altogether.

Long before we lost sight of our daytime luminary, however, all animal and plant life on Earth would cease to exist. The Earth would plunge into eternal darkness and cold while continuing to race through the space of the Universe. There would be no air currents on Earth, no tornadoes or thunderous hurricanes — not even the faintest breeze.

Under the influence of cosmic cold, even the deepest oceans would freeze to the bottom. The Earth would be covered with snow made of liquefied air, turn into a block of ice, and an eternal, profound silence would settle over it. In a word, our planet would in many respects come to resemble its satellite, the Moon. Eventually this lifeless, frozen mass might encounter some new solar system on its journey through space.

Drawn by the gravity of that system's central body, the Earth would begin to circle it along with the other planets already revolving around this new "Sun." The Earth would find refuge in the family of a new world of planets — let us assume, without a fresh catastrophe. It might perhaps be warmed and lit by a new Sun even more strongly than by the old one. It might once again become a "bearer of life," though a renewed one.

The old world, however, would not be reborn. But everything described here is only fantasy. To our great satisfaction, the Earth moves along its orbit around the Sun and can in no way "jump off" it. Our Sun continuously draws the Earth toward itself with tremendous force. And there is no force in nature that could disrupt this gravitational pull of the Sun.

The only conceivable possibility is the intrusion of some other star into our system. Then indeed a terrible catastrophe would break out, like the one described in Wells's science-fiction story "The Star." The Sun not only holds the Earth (and the other planets) at certain, largely unchanging distances from itself — the whole solar system moves somewhere into the boundless cosmic distances.

This happens because the Sun possesses a mass of colossal size. Its volume is one million three hundred thousand times greater than the volume of the Earth, and the Sun's mass is roughly 750 times greater than the mass of all the planets of the solar system taken together. The Sun's gravitational pull is extraordinarily strong. The Earth, revolving around the Sun, never ceases falling toward it, yet can never fall onto it, because its motion by inertia prevents this.

What if the Earth stopped moving along its orbit?

Let us now see what would happen if the Earth, for some unknown reason, suddenly stopped moving along its orbit. The Earth would then plunge toward the Sun at an incredibly great and ever-increasing speed. And in the end it would fall onto it.

We, the inhabitants of the Earth, would soon notice an abundant increase in light and heat. It would at once become unbearably hot for us, even if this catastrophe caught us in winter. The air temperature would rise so quickly, and reach such a figure, that our ordinary thermometers could no longer measure it.

The enormous ice sheets at the North and South Poles would melt rapidly under these conditions, and the water formed by the melting of this ice would turn to steam before it could even spread across the surface of the Earth. The deepest seas and oceans would dry up. All vegetation would burn away. Even the most drought-resistant plants would perish.

Animals and people would burn up together with our whole planet. Even before the Earth managed to come right up to the Sun, it would begin to turn into a lump of white-hot gases. This lump would then be cast into the blazing abyss of the Sun. It must be remembered that the temperature of the Sun's surface is about 6,000 degrees, and there even the most refractory metals exist in the state of intensely heated gases.

But nothing of the sort can happen. Thanks to the Sun's gravity, the Earth will move around our luminary for millions of years, and no catastrophes threaten it.