Our planet contains everything from hard rocks and minerals to millions of living species and natural and man-made structures. How much does the Earth weigh?
How much does the Earth weigh? There is no single answer to this question. Just as people weigh less on the Moon than on Earth, Earth’s weight depends on the gravitational force acting on it, meaning it could weigh trillions of kilograms or nothing at all, depending on where it is.
However, scientists have spent centuries determining the Earth’s mass, which is its resistance to movement under the influence of an applied force. Conform NASAthe mass of the Earth is 5.9722 × 10²⁴ kilograms, which is about 5.89 septillion kilograms. This is equivalent to the mass of about 13 quadrillion pyramids of Khafra in Egypt, each weighing around 4.8 billion kilograms. The mass of the Earth fluctuates slightly due to the addition of cosmic dust and the outflow of gases from the atmosphere, but these tiny changes will not affect the Earth until billions of years from now.
That’s how complicated it is to calculate how much the Earth weighs!
Physicists around the world have yet to agree on the decimal details of this calculation, and determining the Earth’s mass was no easy task. Since the Earth cannot be placed on a scale, scientists have had to calculate mass using other measurable objects. The first key component was Isaac Newton’s law of universal gravitation, as Stephan Schlamminger, a metrologist at the US National Institute of Standards and Technology, explains.
Newton’s law of universal gravitation states that the gravitational force between two objects (F) can be determined by multiplying the masses of the respective objects (m₁ and m₂), dividing the result by the square of the distance between the centers of the objects (r²), and multiplying this result by the gravitational constant (G) , known as the intrinsic force of gravity, i.e. F=G((m₁*m₂)/r²). Using this equation, in theory, scientists could have calculated Earth’s mass by measuring the planet’s gravitational force on an object on its surface. But at that time the exact value of G could not be calculated, scrie Live Science.
Each measurement gave a different result
So how much does the Earth weigh? In 1797, physicist Henry Cavendish performed what would become known as the “Cavendish experiments”. Using a device called a torsion balance, consisting of rotating rods with lead spheres attached, Cavendish measured the gravitational force between the two sets of spheres, noting the angle of the rods changed as the smaller spheres were attracted to the larger ones. Knowing the masses and distances between the spheres, Cavendish calculated G = 6.74 × 10⁻¹¹ m³ kg⁻¹ s⁻².
The Data Committee of the International Science Council currently lists G as 6.67430 x 10⁻¹¹ m³ kg⁻¹ s⁻², only a few decimals different from the value originally calculated by Cavendish. Despite the fact that more than two centuries have passed since Cavendish’s experiment, his torsion balance method is still used, said John West, a physiologist at the University of California, San Diego (USA). But Schlamminger points out that while Newton’s equation and the torsion balance are important tools, their measurements are still subject to human error.
Over the centuries, various scientists have measured G dozens of times, each with slightly different results. The values vary only by thousands of decimal places, but they are enough to sway the calculation of Earth’s mass and enough to make researchers unhappy. “For us, it’s like a little cut on the skin that we have to heal,” says Schlamminger.
However, he believes that the discrepancy in the value of G is not necessarily a bad thing. “Sometimes these cracks that the Universe gives us are the places where we can apply our leverage to gain better scientific understanding. This could be a hint from the Universe, and we don’t want to miss this opportunity,” he adds.
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Source: www.descopera.ro
