Go to Fun_Math Content Table Earth Moon & Sun
Any diagram,which shows a side view of the alignments of the three participants(Sun, Moon & Earth),is widely out of scale.
What we do explore here is how to describe this astronomical phenomenon using the actual object sizes and distances between them.
Radius-km(mile) | Ratio to Earth's Radius | |
---|---|---|
Sun | 695,000km (431,945) | 109 |
Earth | 6,378km (3,964) | 1.0 |
Moon | 1,737.4km (1,079.8) | 0.273 |
Nearest distance -km(mile) | Farthest distance-km(mile) | Variance in % | |
---|---|---|---|
Sun | Perihelion--147,101,455km (91,341,000) | Aphelion --152,098,155km (94,448,000) | 3 % |
Moon | Perigee--356,749km (221,000) | Apogee --406,282km (253,000) | 12 % |
As a first model, earth's distance to the Sun and Moon are set to the mean value,i.e.
To the Sun: 149,600,000 km
To the Moon: 384,400 km
Then,this model looks like this.
**********************************solar_eclipse_model_1.dwg ********************************
To create this drawing :
Load eclipse_model_s.lsp (load "eclipse_model_s")
Then from command line, type test
As seen in this drawing, it is very difficult (if not impossible) to draw lines from the Sun tangent to the Moon, then extending to the Earth. So each of the three objects is displayed in three separate view ports, and all the line drawing operations become possible by switching from one view port to the other.
***************************solar_eclipse_model_0.dwg ***************************
To create this drawing :
Load solar_eclipse.lsp (load "solar_eclipse")
Then from command line, type (setup_solar_eclipse)
Texts in each viewport is added using TEXT command and text height is adjusted for each viewport.
Model-1: Widest darkeness Area :
This happens when the Earth is farthest from the Sun, and the Earth is closest to the Moon.i.e.
Distance To the Sun: 152,000,000 km
Distance To the Moon: 356,700 km
Then,this model gives the following shadows of the Moon (Umbra & Penumbra) on the Earth.
Diameters of the Umbra & Penumbra are 260 km( 162 miles ), and 6700 km( 4164 miles ),respectively.
****************************************solar_eclipse_00.dwg ****************************************
To create this drawing :
Load solar_eclipse.lsp (load "solar_eclipse")
Then from command line, type case_1
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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