Portable analog planetarium indicates the relative time and space angular locations of the sun and planets. Distance measuring scales, angular direction indicators, and typical probe trajectories are included

Baerg, H. R.

English

NASA Technical Reports Server

September 1966
	 Brief 66-10413 
NASA TECH BRIEF
	
.0 
NASA Tech Briefs are issued to summarize specific innovations derived from the U. S. space 
program and to encourage their commercial application. Copies are available to the public from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Analog Solar System Model Relates Celestial Bodies Spatially 
11	 24 
23	 20	
2 0
	 285	 13 
10	 2 
22	 220 2oo	 14
_I 
Venus 
9	 21	 15	 3 
Earth I:jI 
Mercury 
Mars 
The problem: 
To design a portable analog model of the solar 
system to demonstrate the true and apparent day-to-
day motions of the Sun and its orbiting planets. The 
model should include the means to plot the paths of 
man-made satellites and space probes. 
The solution: 
A portable planetarium that indicates the relative 
time and space angular locations of the Sun and
planets. Distance measuring scales, angular direction 
indicators, and typical probe trajectories are included. 
How it's done: 
A flat box has a small sphere located at its center to 
represent the Sun. Successively larger annular plates 
around the Sun sphere represent Mercury, Venus, 
Earth, and Mars respectively. These plates are prop-
erly oriented about the ecliptic pole and offset cen-
trally to represent the actual aphelion and perihelion of 
(continued overleaf(	 - 
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each body's orbit as it relates to the Sun. The incli-
nation and declination in relation to the celestial 
equator is readily represented by tilting the plates in 
predetermined positions relative to one another. 
Grooves in the plates are adapted to receive sliding 
blocks that hold small spheres to represent the four 
planets. Each of the annular plates has the days 
marked on its periphery, starting at the perihelion at 
20-day intervals around the orbital plane through the 
aphelion and on to the perihelion again. The plate 
representing Earth's orbit has the months as well as 
the days marked about its periphery. A square plate 
that conforms to the normal plane of the bottom of 
the box is centrally mounted around the assembled 
annular plates in a position to represent the Sun's 
movement as viewed from Earth. A companion model 
demonstrates the yearly progress of the outer planets 
through the year 2000 AD. It differs from the inner 
planets model in relative distances represented by a 
factor of x20. 
Notes: 
1. A goniometer and a clinometer with distance scales 
(in millions of nautical and statute miles) can be 
used to determine an individual planet's inclina-
tion or declination in relation to the earth or any 
of the other planets. The scale is used to measure 
the relative communication distances between 
any planet and the Sun.
A support on the rear of the box can tilt the model 
forward 23.5° to simulate the inclination of Earth's 
equator to its orbit plane. In addition, daily time 
periods and instrument coordinates for line-of-
sight observation or tracking of probes or planets 
are indicated directly on a 24-hour clock dial. 
To demonstrate the path of a space probe, calcu-
lations are made for a certain firing date and an 
overlay is prepared on clear acetate. By placing 
the overlay on the model, the positions of the 
probe in time can be quickly observed in relation 
to the Sun, Earth and other planets from launch 
through planned orbit. 
Inquiries concerning this invention may be di-
rectedto:
Technology Utilization Officer 
Jet Propulsion Laboratory 
4800 Oak Grove Drive 
Pasadena, California 91103 
Reference: B66-10413 
Patent status: 
Title to this invention has been waived under the 
provisions of the National Aeronautics and Space 
Act [42 U.S.C. 2457 (f)], to the California Institute of 
Technology, Pasadena, California. 
Source: Herbert R. Baerg 
(JPL-l95) 
Brief 66-10413	 Category 01


Analog solar system model relates celestial bodies spatially

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