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Showing posts from August, 2015

Armchair science

Image
I noted with interest this update from the DSCOVR mission:


Cool!  The DSCOVR mission is an Earth-imaging mission that takes a continuous stream of Earth images to monitor it for climate and other changes over time.  It happened to catch the Moon crossing the face of the Earth (go to the link for the animation - you'll be glad you did).  This will happen twice a year, when the plane of DSCOVR's orbit intersects the plane of the Moon's orbit in line with the Earth.

The DSCOVR web page says that the satellite orbits "a million miles" from Earth.  It turns out, you can calculate that distance just from this image and from the known sizes of the Earth and the Moon.  The Earth has a mean radius of 3,959 miles, and the Moon has a mean radius of 1,079 miles.  The ratio between the two is 3.67 - meaning the Earth is 3.67 times as big as the Moon.  But if you open up that image in Photoshop and measure the Earth and Moon in pixels, you will find this:


The Earth is 1595 pi…

*Big* Pluto Icosahedron

I made a Pluto icosahedron from my previous post, and I decided it was nice - but it needed to be bigger.  So I spent today figuring out the geometry to maximize size while minimizing paper.  Here's what I came up with - an icosahedron twice the size as the previous one, taking 4 sheets of paper.  It will be a little more complicated to assemble - you have to match all of the tabs just so - but it makes a nice model when it is complete.

It is in PDF format, since it is four pages.  Without further ado - Pluto.