Measurement to count the distance of earth and moon

How to Measure the Distance to the Moon Using Trigonometry - dummies To figure out how far away the moon is from the earth, consider a circle with the earth at the center and the circumference running right through the center of the moon, along one of the moon's diameters. The moon is so far away that the straight diameter and slight curve of this big circle's circumference are essentially the same measure. The arc that runs through the moon's diameter has an angle of 0.56 degrees and an arc length of 2,160 miles (the diameter). Using the arc-length formula, solve for the radius of the large circle, because the radius is the distance to the moon. To solve for the radius: • First, change 0.56 degrees to radians. Dummies has always stood for taking on complex concepts and making them easy to understand. Dummies helps everyone be more knowledgeable and confident in applying what they know. Whether it's to pass that big test, qualify for that big promotion or even master that cooking technique; people who rely on dummies, rely on it to learn the critical skills and relevant information necessary for success.

The book The Transits of Venus, by Sheehan and Westfall, describes how Aristarchus used Hipparchus' calculation of the Earth-Moon distance, who in turn used Eratosthenes' calculation of the Earth's circumference, to calculate the Earth-Sun distance. Aristarchus of Samos was the first to seriously calculate the distance to the Sun, using geometry. When the Moon is exactly half illuminated when seen from the Earth (first or last quarter phase), then there is a right triangle between the Earth, Moon, and Sun, with the Moon at the right angle. Then he could measure the angular distance in the sky between the Sun and the Moon, plus the Earth-Moon distance and geometry, to get the Earth-Sun distance. The most famous ancient estimate of the earth's circumference as made by Eratosthenes of Cyrene (c. 276-196 BCE), the librarian at the great library at Alexandria. By using a simple gnomon, he found that at Syene, ... the sun at the summer solstice cast no shadow at all: it was exactly overhead. ... At the same moment, at Alexandria, the shadow cast by the sun shows that it stood 7.2 degrees from vertical. This difference is equal to 1/50 of a circle. Using the distance between the cities, Earth's circumference could be calculated. Once the earth's radius is known, the earth itself can be used as a baseline for determining still greater distances -- the distance to the moon. [I]t becomes possible to work out the earth-moon distance indirectly from the geometry of [lunar] eclipses. U...

A handy way to measure distances in the sky. Our conventional methods of measuring distances between two objects on Earth make very little sense when measuring the vast distances between celestial objects. Measuring Angles Because of this, astronomers measure the distance between celestial objects based on the angle they make with an observational point on Earth. Known as angular distances or angular separation, distances are expressed in terms of degrees (°), arc minutes ('), and arc seconds ("). While angular separation primarily describes the apparent distance between celestial objects, as seen from Earth, it can also be used to suggest their actual distance from one another. Imagining Angles in the Sky Like our modern-day timekeeping, the angular method is based on a sexagesimal system– a numeral system with 60 as its base. There are 360° in a circle or sphere, each degree is divided into 60' and each arc minute is further divided into 60". Imagine the sky as a big hollow sphere with the Earth at its center – let’s call this the celestial sphere. This sphere is 360°. If you look above at the sky, you will see only half of the sky i.e. 180° of the celestial sphere. The other half of the celestial sphere is below the horizon and cannot be seen. The point right above you in the sky is the zenith. The zenith is always 90° from the horizon. A “Handy” Way to Measure Distances Hold your hand at arm’s length and close one eye. • Make a fist, with the back of your hand facing y...

Closest Approach (Perigee) Date Local Time Distance in km Distance in miles 21 Jan 21:56 356,569km 221,562mi 19 Feb 10:05 358,267km 222,617mi 19 Mar 16:12 362,696km 225,369mi 16 Apr 04:23 367,968km 228,645mi 11 May 07:05 369,343km 229,499mi 7 Jun 01:06 364,861km 226,714mi 5 Jul 00:24 360,149km 223,786mi 2 Aug 07:52 357,311km 222,022mi 30 Aug 17:54 357,181km 221,942mi 28 Sep 02:59 359,911km 223,639mi 26 Oct 05:02 364,872km 226,721mi 21 Nov 22:01 369,818km 229,795mi 16 Dec 19:52 367,901km 228,603mi * Distances are approximate. Closest Approach (Perigee) is highlighted. Furthest Apart (Apogee) Date Local Time Distance in km Distance in miles 8 Jan 10:19 406,458km 252,561mi 4 Feb 09:54 406,476km 252,573mi 3 Mar 19:00 405,889km 252,207mi 31 Mar 13:16 404,919km 251,605mi 28 Apr 08:43 404,299km 251,220mi 26 May 03:39 404,509km 251,350mi 22 Jun 20:30 405,385km 251,895mi 20 Jul 08:56 406,289km 252,456mi 16 Aug 13:54 406,634km 252,671mi 12 Sep 17:42 406,291km 252,457mi 10 Oct 05:41 405,426km 251,920mi 6 Nov 22:48 404,569km 251,388mi 4 Dec 19:41 404,346km 251,249mi * Distances are approximate. Furthest Apart (Apogee) is highlighted.

Table of Contents: • • • • • • • Do-It-Yourself Guide to Measuring the Moon’s Distance. (/caption) When the distance from the Earth to the Moon comes up, the common figure thrown around is 402,336 km (or 250,000 miles). But have you every wondered how astronomers got that figure? And how exact it really is? There are a couple of ways you can measure the distance of the Moon that don’t … Continue reading “Do-It-Yourself Guide to Measuring the Moon’s Distance” It might be a little more labour intensive than searching the internet, but determining the Moon’s distance yourself is sure to be more fun! If you really want to get involved, check out International Measure the Moon Night on Dec. 10, 2011. Join participants around the world who register their own events and share their images and observations! Video advice: Simple calculation of earth to moon distance I could not find a simple video with this calculation, so i created a crude but straightforward video describing this calculation. Start with the few knowns. We know, as did the Ancient Greeks, that the Moon travels around the Earth at a constant speed – about 29 days per revolution. The diameter of the Earth is also known to be about 12,875 km or 8,000 miles. By tracking the movement of the Earth’s shadow across the Moon, Greek astronomers found that the Earth’s shadow was roughly 2. 5 times the apparent size of the Moon and lasted roughly three hours from the first to last signs of the shadow. How is the distance betw...