What is the exact Diameter of the Earth in miles?

Answer 1

G'day Dragon Warrior,

Thank you for your question.

The diameter of the earth in miles is 7,296 miles at the equator and 7,900 at the poles.

I have attached sources for your reference.

Regards

Answer 2

Diameter Of Earth In Miles

Answer 3

The diameter of the earth at the equator is 7,926.41 miles (12,756.32 kilometers).

But, if you measure the earth through the poles the diameter is a bit shorter - 7,901 miles (12,715.43 km). This the earth is a tad wider (25 miles / 41 km) than it is tall, giving it a slight bulge at the equator. This shape is known as an ellipsoid or more properly, geoid (earth-like).

Answer 4

The diameter of the earth at the equator is 7,926.41 miles (12,756.32 kilometers).
But, if you measure the earth through the poles the diameter is a bit shorter - 7,901 miles (12,715.43 km). This the earth is a tad wider (25 miles / 41 km) than it is tall, giving it a slight bulge at the equator. This shape is known as an ellipsoid or more properly, geoid (earth-like).

Answer 5

the average diameter is 7,926 miles and all exact values vary very little from that exact value, but there is no one exact value since the earth is not an "exact" sphere

Answer 6

The exact circumference of the earth is 25,700 milesaccording to Erastosthenes, a Greek astronomer and geographer in the third century BC.

Answer 7

G'day Dragon Warrior,

Thank you for your question.

The diameter of the earth in miles is 7,296 miles at the equator and 7,900 at the poles.

I have attached sources for your reference.

Regards

Source(s):

Solar System coloring book
http://www.windows.ucar.edu/tour/link=/c...
About Geography
http://geography.about.com/od/learnabout...
Enchanted learning
http://www.enchantedlearning.com/subject...
Fact Monster
http://www.factmonster.com/ipka/a0769141...

Answer 8

It depends on where you want to measure it. It has the greatest diameter at the equator due to rotational forces bulging out the "middle" of the planet.

Answer 9

Through research - about 8000 miles

Answer 10

With or without ice caps ? Measured pole to pole or at Equator?

Anyway the ancients thought the earth was flat First the Pythagoreans argued by induction, 2500 years ago: The moon is round, they said. So is the sun. Surely the earth must also be round. Two centuries later, Aristotle argued from observation. When a boat sails off in any direction, he noted, its hull always disappears before its sails do. The hull is obviously being obscured by curvature, so the earth must be round. Science writer John Noble Wilford notes that going from flat to round meant carving earth down from indefinitely large to a much more confined place. The longest journey on a round earth will sooner or later take you back where you began. Then the Egyptian Eratosthenes, director of the Library in Alexandria, wedded observation to calculation. His idea was as simple as it was brilliant. When the sun was directly above Aswan, 500 miles away, he measured the shadow cast by a vertical tower in Alexandria. The rest was simple trigonometry. He calculated earth's diameter with only 16 percent error, and his method was used right down to modern times

The radius of Earth (or any other planet) is the distance from its center to a point on its surface at mean sea level. Like most planets, Earth is not a perfect sphere, but instead is somewhat flattened at the North and South Poles, and bulges at the equator, which means that its radius and corresponding radius of curvature differs depending on where you measure it (and, in the case of curvature, even which direction is being faced!). This elliptic shape is known as an oblate spheroid/ellipsoid.

Given all of the advancements in measuring technology (including satellites) and tailoring to regional topography, many different reference ellipsoid models have made their way into general usage over the years, providing slightly different values.

However, local variations in terrain negate any chance of pronouncing an absolutely "precise" radius/radius of curvature—one can only find a mathematically precise value based on a given model (with the plethora of—some seemingly outdated—models accommodating regional terrain and accumulated data found from them).

Therefore, the values defined below are based on a "general purpose" model, refined as globally precise as possible, to 5 metres.

The Earth's equatorial radius, or semi-major axis, is the distance from its centre to the equator and equals 6,378.135 km (≈3,963.189 mi; ≈3,443.917 nmi).

The Earth's polar radius, or semi-minor axis, is the distance from its center to the North and South Poles, and equals 6,356.750 km (≈3,949.901 mi; ≈3,432.370 nmi).

The Earth's radius at geodetic latitude,Φ, is:

R(Φ) = Square Root of:

(a^2cos(Φ))^2 + (b^2sin(Φ))^2 divided by (acos(Φ))^2 + (bsin(Φ))^2

SINCE THE DIAMETER IS SIMPLY TWICE THE RADIUS, SO IT IS A SIMPLE CALCULATION IF YOU HAVE YOUR NUMBERS RIGHT.

In 200 B.C., the size of the Earth was actually calculated to within 1% accuracy! Eratosthenes used Aristotle's idea that, if the Earth was round, distant stars in the night sky would appear at different positions to observers at different latitudes. Eratosthenes knew that on the summer solstice, the Sun passed directly overhead at Syene, Egypt. At midday of the same day, he measured the angular displacement of the Sun from overhead at the city of Alexandria - 5000 stadia away from Syene. He found that the angular displacement was 7.2 degrees - there are 360 degrees in a circle, making 7.2 degrees equivalent to 1/50 of a circle. Geometry tells us that the ratio of 1/50 is the same as the ratio of the distance between Syene and Alexandria to the total circumference of the Earth. Thus the circumference can be estimated by multiplying the distance between the two cities, 5000 stadia, by 50, equaling 250,000 stadia.

(1 divided by 50) = (5000 divided by C)

where C = circumference = 5000 x 50 = 250,000

How do we convert to kilometers? Well, we believe that the unit of the "stadium" was about 0.15 km. This means that Eratosthenes estimated the circumference of the Earth to be about 40,000 km.

So how did Eratosthenes do compared to modern measurements? Well, the Earth is almost, but not quite, a perfect sphere, which is what Eratosthenes assumed. The Earth is actually slightly flattened. The measured circumference around the equator is 40,075 km, which is longer than the circumference through the poles of 40,008 km. Eratosthenes was measuring the latter, and got it almost exactly right. We're not sure the exact conversion factor from stadium to km, so we don't know exactly how close his number was to the modern value.