This post will show a way to calculate the diameter and radius of the moon. These can be determined from the angular width of the Moon viewed from the Earth and using simple trigonometry. The following need to be obtained from elsewhere: r = average Earth-Moon distance = 379800 km (get from solution to one […]
How to calculate the radius of the moon Read More »
This post will show a way to calculate the diameters and radii of the planets. These values can be determined when the planet is aligned with the Sun and the Earth. Then, knowing the time period of the planet’s orbit around the Sun and measuring the angular width of the planet by an observer on
How to calculate the radii of the planets Read More »
This post will show a way to calculate the diameter and radius of the sun. These values can be determined from the angular width of the Sun viewed from the Earth and using simple trigonometry. The following need to be obtained from elsewhere: r = average Sun-Earth distance = 134030000 km (get from solution to
How to calculate the radius of the sun Read More »
This post will show a way to calculate the approximate mass of the sun. The value can be determined from knowing the time period of the Earth’s orbit around the Sun and assuming the Earth’s orbit is circular (which it very nearly is). Need to obtain the following from elsewhere: D = average Sun-Earth distance
How to calculate the mass of the sun Read More »
This post will show a way to calculate the approximate distances between the sun and planets. This method requires the following steps:Step 1: Use Kepler’s third law to determine the approximate distance of each planet from the Sun as a fraction of the Sun-Earth distance. (Kepler’s third law was published sometime between 1609 and 1619.)Step
How to calculate the distances between the sun and planets Read More »
This post will show a way to calculate the approximate distance between the earth and the moon. This value can be determined from knowing the time period of the Moon’s orbit around the Earth and assuming the Moon’s orbit is circular. The computation here uses the equation for the gravitational force developed by Isaac Newton
How to calculate the distance between the earth and the moon Read More »
This post shows a way to calculate the approximate mass of the earth. The computation uses Isaac Newton’s second law and his equation for the gravitational force, both published in his book “Principia” in 1687. The following need to be obtained from elsewhere: R = average radius of Earth = 6370 km = 6370000 m
How to calculate the mass of the earth Read More »
This post shows an approximate way to calculate the radius of the earth as well as the circumference of the earth. This post uses the method of Eratosthenes. Eratosthenes (born 276 BC, died 194 BC) of Alexandria, Egypt was the first person to calculate reasonably accurate values for the circumference and radius of the Earth.
How to calculate the radius of the earth Read More »