Sister Spot on the Moon

Find where your location on the Earth corresponds to the Moon.

Run the code to mark your location on a map of the world:

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Mark your position on a map:

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Expand the view to the whole world:

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Draw a red disk around your position. Try other radius values:

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Draw a disk with a 200-mile radius centered at your location. To specify the 200-mile radius, type += to get a natural language input box and type 200 miles:

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Make the disk easier to see by coloring it red and giving it a black edge:

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Mark the corresponding position on the Moon:

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The Moon has a {latitude,longitude} coordinate system just like Earths.

Mark your Earth {latitude,longitude} on the Moons coordinate system:

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Show the Earth and Moon maps together:

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Row formats a list of items as a sequence without braces and commas:

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Use Row to show the Earth and Moon maps together (with an intervening space):

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The maps automatically downscale when theyre in a Row. Make them larger with ImageSize:

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The red disk is larger on the Moon map than on the Earth map because the Moon is smaller than the Earth.

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Use a more familiar projection:

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Were used to seeing the Earth as a rectangular map, but not the Moon. An orthographic projection gives a more familiar round image, like you would see if you viewed the Earth or Moon from space. Specify GeoCenterHere to put your location at the center of the map:

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Show the Earth and Moon together:

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Add longitude and latitude lines for better orientation:

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Add longitude and latitude grid lines to the Earth map:

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Draw the equator and Greenwich meridian as well. The Greenwich meridian is the line at longitude 0, which passes through a historic observatory at Greenwich in London:

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Add the same lines to the Moon map. On the Moon, the GreenwichMeridian marks the center of the side of the Moon that faces the Earth:

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The gray lines are nearly invisible on the gray Moon. Improve their visibility by making them transparent black:

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Show the Earth and Moon maps together:

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Share ItMake a website that gives the sister spot on the Moon of a location you enter:

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Deploy a form that asks for a location and makes a map of it and its sister spot on the Moon:

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Click the link in the output to visit the site.

Share the link by right-clicking it and choosing Copy Address. Paste the link into an email, tweet, or other message.

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