Go to Fun_Math Content Table Earth Moon & Sun
The lunar plane of revolution is inclined with respect to the ecliptic by an angle which varies 20 minutes around 5 degrees.The two points where the Moon's revolution plane and the ecliptic meets are called "nodes". When the moon is on the nodes, the Sun,moon,and the Earth are in the same plane , and depending on the relative locations, Solar or Lunar eclipses can happen.
The most common thing which is caused by the revolution of the moon is the changing phase of the Moon.
The simple model assumes the Earth and Moon in the same plane.
The sun light is so distance that during the Moon's rotation around the Earth
the light is uniform and parallel.
The model is made up of 12 moons placed equally spaced around the Earth.
The viewer is on the dark side of the Earth looking at the center of the Moon
**********lunar_phase_model.dwg**********
To create this drawing:
#1 Just download lunar_phase_model.dwg and render.
light direction data is already in the dwg file
#2 From scratch using AutoLISP program
Load lunar_phase.lsp (load "lunar_phase")
Then from command line, type (setup_lunarphase)
Thiw will create 12 moons around the global coordinate (0 0 0).
You can add a sphere of radius 2.0 at this center point to represent the Earth.
In AutoCAD, issue LIGHT command and define the distant light coming from direction (0 1 0)
Then use RENDER to render the drawing.
Program name: Lunar_Phase.lsp
Command : Lunar_phase
******************************lunar_phase_screen.dwg******************************
To create this drawing:
#1 Just download lunar_phase_screen.dwg and render.
light direction data is already in the dwg file
#2 From scratch using AutoLISP program
Load lunar_phase.lsp (load "lunar_phase")
Then from command line, type lunar_phase
This will create 12 moons around the global coordinate (0 0 0), and 12 viewports,each of which
is a zoomed picture of the moon in each position vewed from the Earth.
The numbers from 0 to 11 in the viewports in the following drawing corresponds to the numbers of
the Moon's position.
********lunar_phase_viewport.dwg********
In AutoCAD, issue LIGHT command and define the distant light coming from direction (0 1 0)
Then use RENDER to render the drawing.
Lunar Phases, starting from a New Moon, then First quarter, Full moon, Waning quarter, are shown in animation.
To create this animation:
After all the moons are rendered, go to each viewport, and issue command "saveimg",
and save the image file in BMP format. So ,for example, moon_1.bmp, moon_1.bmp, ... ,moon_11.bmp
will be created. Then call up PaintShop program and create animation as a slide .
All comments should be sent to Takaya Iwamoto
Last Updated July 9-th, 2006
Copyright 2006 Takaya Iwamoto All rights reserved.
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