# Moon size. Calculation and confirmation.

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The duration of an eclipse is directly proportional to the size of the object, all other things being equal (distance and speed). The duration of the total phase of a solar eclipse is 7.5 minutes (the Moon completely covers the Sun for 7.5 minutes). The duration of the total phase of the lunar eclipse is 108 minutes (the Earth completely covers the Sun for 108 minutes). With the same distance between the Moon and the Earth. At the same speed of the Moon (the orbit of the Moon moves with the speed of the Earth). The diameter of the Earth is 12,742 km. Therefore, the diameter of the Moon can be calculated using the following formula: 12 742 * (7.5 / 108) = 885 km. The official diameter of the Moon is 3,474 km. Moreover, the result of calculating the diameter of the Moon quite accurately coincides with the size of the track between South America and Antarctica (875 km. + - 25 km.), which confirms the calculation and minimizes probability of a simple coincidence.

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57 minutes ago, AlexandrKushnirtshuk said:

The diameter of the Earth is 12,742 km. Therefore, the diameter of the Moon can be calculated using the following formula: 12 742 * (7.5 / 108) = 885 km. The official diameter of the Moon is 3,474 km.

Better results than 885 km were already available more than 2000 years ago. Here is short presentation of Aristarchus and the Moon: http://www.astronomy.ohio-state.edu/~thompson/1101/aristarchus_martini.pdf.
Wikipedia has some facts and links: https://en.wikipedia.org/wiki/Aristarchus_of_Samos

Currently the precision is better since the distance to the moon is known with good precision, see for instance https://en.wikipedia.org/wiki/Lunar_distance_(astronomy)#Radar

What is the purpose of posting a calculation that gives an obviously incorrect value? Why not ask or learn how correct calculations and observations works?

Edited by Ghideon
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!

Moderator Note

You were told to not re-introduce this.

As Ghideon notes, your result is wrong; this should lead you to first investigate to find errors in your model. for example, 7.5 minutes is the longest solar eclipse ever calculated. It’s not typical, nor is it a constant. It depends on multiple factors.

A total lunar eclipse can last up to nearly 2 hours, but it is similarly not a constant

I’ll leave this open to allow discussion of errors in your model. But any further insistence that your calculation is correct will result in closure, and possibly suspension.

One rather obvious issue is that the moon is moving in the opposite direction for each type of eclipse, so this simple geometry argument would seem to be lacking.

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2 hours ago, AlexandrKushnirtshuk said:

The duration of an eclipse is directly proportional to the size of the object, all other things being equal (distance and speed). The duration of the total phase of a solar eclipse is 7.5 minutes (the Moon completely covers the Sun for 7.5 minutes). The duration of the total phase of the lunar eclipse is 108 minutes (the Earth completely covers the Sun for 108 minutes). With the same distance between the Moon and the Earth. At the same speed of the Moon (the orbit of the Moon moves with the speed of the Earth). The diameter of the Earth is 12,742 km. Therefore, the diameter of the Moon can be calculated using the following formula: 12 742 * (7.5 / 108) = 885 km. The official diameter of the Moon is 3,474 km. Moreover, the result of calculating the diameter of the Moon quite accurately coincides with the size of the track between South America and Antarctica (875 km. + - 25 km.), which confirms the calculation and minimizes probability of a simple coincidence.

What makes you think the diameter of the moon has any relation to the distance between Tierra del Fuego and the tip of Antarctica?

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1 hour ago, swansont said:

As Ghideon notes, your result is wrong; this should lead you to first investigate to find errors in your model. for example, 7.5 minutes is the longest solar eclipse ever calculated. It’s not typical, nor is it a constant. It depends on multiple factors.

7,5 and 108 minutes are the maximum values of solar and lunar eclipses, and therefore may well be taken as constants in calculations.

1 hour ago, swansont said:

One rather obvious issue is that the moon is moving in the opposite direction for each type of eclipse, so this simple geometry argument would seem to be lacking.

With the same distance between the Moon and the Earth. At the same speed of the Moon (the orbit of the Moon moves with the speed of the Earth).

4 minutes ago, exchemist said:

What makes you think the diameter of the moon has any relation to the distance between Tierra del Fuego and the tip of Antarctica?

From the quote you quoted above your question, it is quite understandable why I assume that the Moon left a trail between South America and Antarctica. The calculated and actual sizes coincide quite accurately.

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24 minutes ago, AlexandrKushnirtshuk said:

7,5 and 108 minutes are the maximum values of solar and lunar eclipses, and therefore may well be taken as constants in calculations.

You didn’t provide evidence of this, and need to, and also show they are maximum under the same conditions.

Quote

With the same distance between the Moon and the Earth. At the same speed of the Moon (the orbit of the Moon moves with the speed of the Earth).

The moon in between the earth and sun moves in one direction, the moon on the far side of the earth is moving in the opposite direction. Because the earth is moving, one is in the same direction of the earth’s orbit, the other is in the opposite direction. This will affect the duration of the eclipses. It’s not simple geometry, as if the earth was stationary.

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21 minutes ago, swansont said:
45 minutes ago, AlexandrKushnirtshuk said:

7,5 and 108 minutes are the maximum values of solar and lunar eclipses, and therefore may well be taken as constants in calculations.

You didn’t provide evidence of this, and need to, and also show they are maximum under the same conditions.

2) Total duration of lunar eclipse. (an hour and three-quarters in english version, 108 minutes in russian).

The diameter of the lunar orbit and the speed of the Moon are constant values (same conditions). + - small eccentricity of the lunar orbit.

21 minutes ago, swansont said:

The moon in between the earth and sun moves in one direction, the moon on the far side of the earth is moving in the opposite direction. Because the earth is moving, one is in the same direction of the earth’s orbit, the other is in the opposite direction. This will affect the duration of the eclipses. It’s not simple geometry, as if the earth was stationary.

Since the Moon's orbit moves with the speed of the Earth, then in this case (in this frame of reference) the Earth can be considered stationary.

The calculation is based on the principle of scientific proportion, and on three reliable parameters. The calculation pretty closely matches the actual track size between South America and Antarctica. Point.

Edited by AlexandrKushnirtshuk
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1 hour ago, AlexandrKushnirtshuk said:

7,5 and 108 minutes are the maximum values of solar and lunar eclipses, and therefore may well be taken as constants in calculations.

With the same distance between the Moon and the Earth. At the same speed of the Moon (the orbit of the Moon moves with the speed of the Earth).

From the quote you quoted above your question, it is quite understandable why I assume that the Moon left a trail between South America and Antarctica. The calculated and actual sizes coincide quite accurately.

Er, no it isn't, actually. But this is too bonkers for me. I'm out.

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21 minutes ago, AlexandrKushnirtshuk said:

Since the Moon's orbit moves with the speed of the Earth, then in this case (in this frame of reference) the Earth can be considered stationary.

No, it can’t. The elapsed time depends on their relative speed. This is one reason why you are getting the wrong answer. Assuming the earth is at rest is a horrible approximation.

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I suggest you to download and install a 3D application e.g. Blender and creation of cosmic objects: Earth, Moon and Sun with exactly the same parameters as you can find in Wikipedia articles. Then start animation in 3D. You will be able to check whether these parameters are working correctly and give you well known results..

Edited by Sensei
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51 minutes ago, AlexandrKushnirtshuk said:

The calculation is based on the principle of scientific proportion, and on three reliable parameters. The calculation pretty closely matches the actual track size between South America and Antarctica. Point.

Please explain your logic behind the calculation. A solar eclipse means the moons shadow covers a small portion of the earth. And during a lunar eclipse the whole moon is completely in earth shadow. What is the division of the times (7.5 / 108) supposed to represent?

58 minutes ago, AlexandrKushnirtshuk said:

Earth can be considered stationary.

The earth rotates during a solar eclipse.

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Earth and Moon to scale. The shadow of the moon on the surface of the Earth during a solar eclipse (view from space). The size of the shadow is more consistent with an object with a diameter of 3,500 km., or 850 km.?

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Moderator Note

You were warned

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