How did Eratosthenes determine the size of the Earth

Eratosthenes erected a pole in Alexandria, and on the summer solstice he observed that it cast a shadow, proving that the Sun was not directly overhead but slightly south. Recognizing the curvature of the Earth and knowing the distance between the two cities enabled Eratosthenes to calculate the planet’s circumference.

How did Eratosthenes measure the size of Earth?

Eratosthenes hired a man to pace the distance between the two cities and learned they were 5,000 stadia apart, which is about 800 kilometers. He could then use simple proportions to find the Earth’s circumference — 7.2 degrees is 1/50 of 360 degrees, so 800 times 50 equals 40,000 kilometers.

How did Eratosthenes estimate the size of the Earth in 240 BC?

How did Eratosthenes estimate the size of the earth in 240 bc? By comparing whether sun light could reach water down in water wells in two cities at different latitudes and using simple trigonometry. … On the vernal equinox the spin axis of the earth and a line between the earth and the sun are perpindicular.

How did Eratosthenes measure the size of the Earth quizlet?

How did Eratosthenes measure the circumference of the Earth? He used geometry and ratios to determine the size of the Earth, by basing his calculations on observations of the sun.

How did Eratosthenes measure the size of the Earth Quora?

Originally Answered: How did Eratosthenes measure the size of Earth? That meant the Sun must be straight overhead. Eratosthenes had someone measure the distance between Alexandria and Syene. He used that distance, what he knew about the Sun’s angles, and a bit of geometry to figure out the size of the Earth.

How do they measure the Earth?

Earth’s circumference is the distance around Earth. Measured around the Equator, it is 40,075.017 km (24,901.461 mi). Measured around the poles, the circumference is 40,007.863 km (24,859.734 mi). Measurement of Earth’s circumference has been important to navigation since ancient times.

How do we measure the size of the Earth?

The answer is 360°/10° = 36. This tells us that Earth’s circumference is simply equal to 36 times the distance between the pair of trees! When the shadows of two vertical structures point toward or away from each other, the size of Earth can readily be calculated.

What scientific measurement did Eratosthenes the director of the Alexandria Library make how accurate was he?

The measurement of Earth’s circumference is the most famous among the results obtained by Eratosthenes, who estimated that the meridian has a length of 252,000 stadia (39,060-40,320 km), with an error on the real value between −2.4% and +0.8% (assuming a value for the stadion between 155 and 160 metres).

How was the size of the Earth First estimate quizlet?

How was the size of the Earth first estimated? Calculations based on the difference in the angular position of the Sun in different cities a known distance away from each other. How was the distance of the Earth to the Sun first calculated? Using the angle between the Moon and the Sun during first quarter.

What is the circumference of the earth using Eratosthenes method quizlet?

The lad measured the circumference of the earth. He was told that at a certain time, the sun was going to line up perfectly perpendicular to a well that was located in Syene. So Eratosthenes measured the distance from Syene to his place in Alexandria. He measured this distance to be 500miles.

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What was Eratosthenes experiment?

Eratosthenes analyzed the observations with the assumption that the earth is a sphere and the sun is very far away. The geometry of the situation is sketched at the right. He concluded that the circumference of the earth was about 50 times greater than the distance from Alexandria to Aswan.

Is Eratosthenes method of determining the circumference of the Earth logical and reasonable Why?

Eratosthenes reasoned that the ratio of the angular difference in the shadows to the number of degrees in a circle (360°) must equal the ratio of the distance to the circumference of the Earth. The resulting estimate, about 25,000 miles (40,234 km), is astonishingly accurate.

How was the size of the Earth first measured?

On the day the Sun shone on the bottom of the wells in Syene, Eratosthenes measured the Sun’s position in the sky over Alexandria. It was seven degrees away from the zenith, meaning Syene must be seven degrees away from Alexandria as measured on the circle that is Earth’s circumference.

How did Eratosthenes measure the circumference of the Earth using parallel lines?

Eratosthenes calculated the distance between Alexandria and Syene using records involving camel caravans. The distance he used was 5000 stadia. Thus, the circumference of the Earth is 250,000 stadia, which translates to somewhat less than 25,000 miles (depending on how ancient units convert to modern units).

How was Earth's diameter measured?

This means that Eratosthenes estimated the circumference of the Earth to be about 40,000 km. He also knew that the circumference of a circle was equal to 2 times π (3.1415…) times the radius of the circle. … The diameter of a circle is twice the radius, giving us a diameter for Earth of 12,756 km.

Why did Aristarchus's critics think that the Earth was stationary?

The ancient Greeks knew about parallax, so why did Aristarchus’s critics think Earth was stationary? (Select all that apply.) They didn’t realize that stars could be very, very far away. (They didn’t understand that stars could be so far away, making their parallax undetectable.)

What method was used to make our most accurate measurement of the astronomical unit?

In principle, the easiest way to determine the value of the astronomical unit would have been to measure the Earth-Sun distance directly by means of the parallax method.

What method was used to make our most accurate measurement of the astronomical unit though later measurements were more accurate )?

What method was used to make our most accurate measurement of the astronomical unit (though later measurements were more accurate)? Measuring the time it took for light sent to Venus to bounce back and reach Earth. What is the baseline we use to calculate the distance of stars to the Earth?

What do scientists mean by verifiable observations?

What do scientists mean by verifiable observations? – observations that can be interpreted in only one way. – observations that support a scientific theory. – statements that anyone can, in principle, verify for himself or herself. – observations that a model does not have to predict.

How did Eratosthenes know the time?

Eratosthenes actually measured the length of the shadow of a tall building in Alexandria when the Sun reached its highest point in the sky on the Summer Solstice. This corresponds to noon in both Alexandria and Syene, where the Sun cast no shadow at the bottom of a deep well (hence the Sun was directly overhead).

What was Eratosthenes impact?

Eratosthenes made many other major contributions to the progress of science. He worked out a calendar that included leap years, and he laid the foundations of a systematic chronography of the world when he tried to give the dates of literary and political events from the time of the siege of Troy.

What is the meaning of Eratosthenes?

Eratosthenes Add to list Share. Definitions of Eratosthenes. Greek mathematician and astronomer who estimated the circumference of the earth and the distances to the Moon and sun (276-194 BC) example of: astronomer, stargazer, uranologist. a physicist who studies astronomy.

What is the circumference of Earth quizlet?

The polar circumference of Earth is 40, 008 km.

Why did the ancients believe that celestial objects had some control over their lives?

Why did the ancients believe that celestial objects had some influence over their lives? They realized that seasonal changes were related to the positions of celestial bodies, so they figured that these objects could control other aspects of their lives.

Which of the following examples describes a situation where a car is experiencing a net force?

Which of the following examples describes a situation where a car is experiencing a net force? The car is making a gradual turn. Consider the statement “There’s no gravity in space.” This statement is: … Two examples are a car driving down the highway or the movements of the molecules of liquid in a cup of hot coffee.

Why was the Eratosthenes experiment important?

Eratosthenes assumed that Earth is a sphere and that the solar rays are parallel when they reach Earth. … Eratosthenes’ experiment was one of the most important experiments in antiquity and his estimate of the earth’s size was accepted for hundreds of years afterwards.

Why is Eratosthenes called the father of geography?

Eratosthenes was called “The Father Of Geography,” since he was very knowledgeable about the earth. He invented a system of latitude and longitude and he also might have calculated the distance from earth to the sun and invented the leap day.

Did Eratosthenes use a protractor?

Eratosthenes measured the Earth to within 2% of the modern measured value. Using a stick, protractor, and a piece of string you students can easily do as well.

Why is it important to know the circumference of the earth?

Measuring the circumference of the Earth was of obvious importance for civilizations around the world. … Understanding the size of Earth and its circumference helped early civilizations be able to visualize a bigger world while still being able to improve their place in it.

How do you calculate the circumference of the Earth's orbit?

Circumference of the Earth’s Orbit = 2*pi*R = 942,000,000 kilometers. Time to complete one Orbit = 365.2422 days = 8766 hr. Speed of Revolution = Distance/Time = 942,000,000 km / 8766 hr = 107,000 km/hr = 30 km/sec.