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FIG. 3. INVENTOR. ARMAND N. SPTZ
BY
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March 24 1953 A. N. SPITZ
PLANETARIUM
Filed May 3 1948 6 Sheets—Sheet 6
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FIG. 9.
INVENTOR.
ARMAND N. SPITZ
BY
Patented Mar. 24 1953
UNITED STATES PATENT OFFICE

PLANETARIUM
ArmandN. Spitz Lansdowne Pa.
Application May 3 1948 Serial No.
12 Claims. (Cl. 88—24)
10 15
20 25
40 45 50 56
1
This invention relates to a planetarium and particularly to one of small size and inexpensive construction but nevertheless suitable for use in astronomical instruction or demonstration.
The large and elaborate planetaria located in various parts of the world are of course capable of demonstrating the relationships and motions of the heavenly bodies to a high degree of accuracy and detail. However they are correspondingly extremely expensive in view of the elaborate optical systems used and the intricate devices involved which will duplicate to a high accuracy of realism the locations and motions of the stars planets and other bodies.
It is a general object of the present invention to provide a planetarium of quite simple and inexpensive construction which is particularly adapted fqr use in teaching astronomy and navigation in small schools museums and other institutions or even forhome use where a large outlay of money is out of the question. In accordance with the invention these ends are achieved with very little loss of realism as contrasted with the expensive planetaria above mentioned. For example these expensive planetaria project on domes images of the stars which are true circles and which are true in their brightness relationships. However for realism the dome is darkened so as to simulate the night sky and the images of the stars are dimmed to such degree as to simulate their visual intensities when viewed in the darkness. Actually under these conditions the human eye is very little appreciative of the high accuracies of reproduction of the stars by these large planetaria. Under low intensities of illumination the eye cannot discern to any substantial degree whether a particular projected spot of light is truly circular or not. Furthermore of two spots having equal intensities over equal areas that spot which presents the larger area will appear brighter. In accordance with the present invention projection of the stars and planets is provided merely in the form of the projection through pinholes of various sizes of the images of concentrated filament lamps. When closely examined such images are of course images of the lamp filaments blurred to a greater or less extent depending upon the sizes of the pinhole openings and the sizes of the lamp filaments. Nevertheless in a room darkened to the proper extent to simulate nighttime conditions these images when viewed from distances of the order of upwards of about five feet simulate the appearance of stars to the average eye to such extent as to rnakethis mode of projection highly acceptable.30 holes being directed nonradially when the poly
2
One of the subsidiary objects of the invention is accordingly the achievement of these satisfactory results by the use of a simple projection system of the type just indicated.
It may be here noted that the projection effected by the present planetarium may be upon the inside of a . spherical or approximately spherical dome but quite acceptable results are secured by projection on the flat ceiling and walls of a conventional room or hall:
In achieving simple and inexpensive construction there is a further highly important feature of the invention.. The use of a projection system such as just described would indicate the desirability of using a' sphere of opaque material at the center of which a lamp would be mounted with radially extending pinholes through the surface of the sphere. If a large number of stars are to be projected in their proper relationships it would be necessary to drill or otherwise form in such a sphere a correspondingly large number of pinholes. To do this on a spherical surface is a quite difficult operation. In accordance with. the present invention there is used instead of a sphere a globe in the form of a polyhedron having plane faces. If such faces are drilled in flat
form there will of course be approximately radial
conditions of the holes only in the vicinity of
the centers of the plane faces the peripheral
hedron is assembled. It has been found that
with a proper choice of polyhedron the effectof
this condition is negligible in destroying the simu
lation of stars by the images projected through 35 the holes. Of the possible polyhedra the regular dodecahedron and the regular icosahedron have been found most suitable with the former offering some :advantages despite the smaller number of sides. The reason for this may be ascribed to the fact that the angles between radii and normals to the pentagonal sides of the dodecahedron are smaller at the vertices of the sides than in the case of the icosahedron so that the axes of the holes actually deviate less from radii at the vertices of the faces of the dodecahedron than they do at the vertices Of the faces of the icosahedron.  There may of course be used various other nonregular polyhedra but a survey of the possibilities indicates the rather considerable advantages of the regular dodecahedron in that it represents the best compromise between a minimum number of sides and least deviation of the axes of peripheral holesfrom the radii. Ratherobviously of course a truncated

3 4
dodecahedron would be superior to the regular Figure 9 is a plan view of the planet projector
dodecahedron but the very substantial increase Figure 10 is a side elevation thereof
in number of sides makes considerably more diffi Figure 11 is a section taken on the broken plane
cult the layout and drilling of pinholes without indicated at I I—I I in Figure 9
sufficient advantages to justify the difficulties. 5 Figure 12 is an enlarged fragmentary section
Another object of the invention is to provide showing the left hand portion of Figure 11
a simple projector for the planets the sun and Figure 13 is a fragmentary plan view showing
the moon and in the case of the moon to pro in particular the masking means for demonstrate
vide a suitable demonstration of its phases. From ing the phases of the moon
a theoretical standpoint the last mentioned pro 10 Figure 14 is a section taken on the plane indijector may not when it is of reasonable size show cated at 14—14 in Figure 13
the planets and the sun and moon in sufficient Figure 15 is a view showing a typical face of
proximity to the plane of the ecliptic. However the dodecahedron having pinholes therein
here again the memory of the observer is not suf Figure 16 is a vertical section illustrating the
ficiently accurate to render obvious any substan 15 construction of the base of the instrument
tial deviation from reality. From a qualitative Figure 17 shows in two parts a development of
standpoint the effects produced are thoroughly the scale indicating hours and minutes and
satisfactory and in fact even a quantitative re months and days and provided for the adjust
sult is almost secured. ment of the elements of the planet projector
In this last named projector provision is made 29 Figure 18 is a plan view showing a scale assofor the simple relative shifting of the bodies and elated with the adjustment of the mounting for
there is provided an index ring graduated in the projectors
hours of right ascension and also in calendar Figure 19 is a detailed sectional view showing
days so that from astronomical tables the posi a brush arrangement involved in making electri
tions of the bodies may be quite accurately 25 cal connections with the star projecting lamp
located for any particular time. Figure 20 is an elevation partly in  section
The phases of the moon may also be demon showing a pointer which may be used in associa
strated quite realistically even though not con tion with the apparatus by a demonstrator to
tinuously through the use of a simple masking point  to particular portions of the projection
arrangement. 20 and
In the case of both stars and planets the in Figure 21 is a wiring diagram indicating the
vention also provides for the indication of these electrical wiring of the device.
bodies in their proper color relationships this The planetarium comprises a base 2 in which
end being achieved simply by the use of trans is secured a supporting post 4 carrying the pivot
parent color filters covering the pinholes through 35 6 for a saddle 8 there being provided a clamp
which the projection is effected. ing knob 9 for fixing the saddle in angularly
A further object of the invention is the provi adjustable position which is indicated by a scale
sion of a motor drive by means of which continue 10 (see Figure 18) moving adjacent to a fixed
ous proper motions of the star planet and other index marker 12. This scale indicates the view
images may be secured. This drive also involves 40 point of observation of the heavens for exam
the possibility of hand operation without inter pie when adjustment is made to bring the north
ference with the motor drive so that the dem 40 marking to the index the simulation will be
onstrator may at any time shift the images for of the skies as viewed at a latitude of 40º north.
wardly or backwardly or cause them to stand As indicated by the scale the apparatus is
still temporarily with or without disconnecting adapted to show the skiesas viewed from the
the driving motor. 45 north pole to about 30º south latitude. The sad
All of the objects heretofore indicated as well dle 8 is desirably made quite thin so that its
as other objects relating to various details such action in occulting the star images is negligible
as the location of the equinoxes and solstices in fact during operation unless an observer is
will become apparent from thefollowing descrip carefully following a particular star the posi
tion read inconjunction with the accompanying 50 tion of the saddle will not be noticeable.
drawings in which: Referring to Figure 7 there is particularly
Figure 1 is a side elevation of the complete illustrated therein the lamp mounting. In the
instrument showing both the star and planet upper end 14 of the saddle there is fixed a rod
projectors 16 which carries an arcuate member 18 prefer
Figure 2 is an elevation showing certain details 55 ably in the plane of the saddle and also flat
of the drive mechanism which is provided with a bearing member 20 at
Figure 3 is a side elevation partly in section its lower end. This bearing member is provided
also showing the drive mechanism with extensions 22 providing a fork. The bear
Figure 4 is an axial sectional view showing in ing 20 is provided with insulating rings in which
particular a clutch arrangement permitting 00 there is mounted a rod 24 with resulting elec
hand drive independent of the driving mecha trical insulation from the bearing member 20.
msm This rod 24 extends within the upper end of a
Figure 5 is an elevation showing the face of shaft 26 being also insulated therefrom through
a worm gear forming part of the clutch mecha a suitable insulating sleeve and is electrically
nism 65 connected through an insulated screw 27 to a
Figure 6 is a fragmentary section taken on the collector ring 48 also insulated from the shaft
arcuate surface indicated at 6—6 in Figure 5 26. The shaft 26 extends through bearings 28
Figure 7 is a fragmentary elevation partly in and 30 the latter being carried by a housing 32
section showing particularly details of the lamp 70 secured to the lower end of the saddle and from
mounting whereby occulting of the illumination this housing the shaft extends in the form of
is continuously effected at the horizon an extension 26'.
Figure 8 is a view taken at right angles to that Trunnions 34 extending from a cup 36 are pier
of Figure 7 serving also to illustrate the lamp oted in bearings in the fork members 22. The
mounting and occulting arrangement 75 cup is weighted by a weight 38 so that its axis
.9
5 will always remain vertical. 6
        Within the cup a erably at a rate which will produce slow motion
lamp 40 is supported in a socket 42 one terminal such as will enable observers to follow the stars
of which is grounded to the cup while the other quite readily.
terminal is connected to a flexible insulated wire The globe is indicated as a unit at . As in
44 which in turn is connected to a spring wiper 5 dicated in the introduction to this specification
46 engaging the end of the rod 24 this wiper it is desirably in the form of a polyhedron and
being insulated from its support on the mem preferably in the form of a dodecahedron having
her H. twelve pentagonal sides. Other polyhedra may
        The lamp 40 is of a low voltage type having a be used but as previously indicated the dodec very concentrated filament to provide a light 10 ahedron is preferred since it has the optimum
source of very small surface as viewed from any properties consistent with ease of manufacture
direction. The filament is desirably substan and satisfactory projection results. An icosa
tially in the plane of the upper edge of the cup hedron of twenty sides each in the form of an
36 with the result that the edge of this cup de equilateral triangle is also quite satisfactory as fines the horizon below which projection will not 15 are various other polyhedra which need not be
occur. As will be evident the suspension of the regular i. e. which may have different types
cup will maintain its upper edge in a horizontal of sides or which may have absence of complete
plane despite either rotation of the globe or tilt symmetry. Many such polyhedra will be found
ing of the saddle the axis of the trunnions 34 among crystal forms and it is believed that fur
always horizontal. 20 ther discussion thereof is not necessary. It may
        Reference to Figure 19 will indicate how cur be here remarked that certain aspects of the in
rent isconducted through the lamp filament. vention can obviously be applied to the use of
The collector ring 48 referred to above is en spherical globes as well as polyhedral globes
gaged by a plunger 50 under the action of a but spherical globes in general involve such spring 54 and current is conducted to the spring 25 difficulties of manufacture that they are not to
and the plunger through a lead 56. All of these be preferred.
elements are housed in an insulating tube 52 The arrangement of the preferred dodeca
clamped to the saddle 8. The path of current is hedral globe is as. illustrated in Figure 1 with
thus from the conductor 56 through the lamp an upper group of pentagonal sides  a lower to' the frame of the planetarium which consti go group of sides  and top and bottom penta
tutes the ground. gonal sides  and . The mounting axis is
        To the shaft 26 there is secured a large worm through the centers of the last two sides which
wheel 58 meshing with a worm 60 the shaft 62 are provided respectively at  with a bearing
of whichis provided with a collar 66 and extends secured to the face and surrounding the rod 16 through the housing 32 to carry a hand wheel 35 and with a member  which is clamped to the
64 through which manual rotation may be im upper end of the shaft 26. The globe accord
parted to the shaft 26. As viewed in Figure 2 ingly revolves with the shaft 26 about the axis
a left hand extension 10 of the worm shaft has of the shaft which constitutes the polar axis.
a. bearing at. 09 in the housing. Journalled on The faces of the dodecahedron may be formed
this shaft is a worm wheel 12 which is provided 40 of various materials for example of sheet metal
with sockets .14 each of which is formed. as indi such as aluminum or of sheets of plastic mate
cated in Figures 5 and 6 with one relatively rial. The edges of the faces may be secured to
slightly inclined end and with the other end each other in any desired manner but when
relatively abrupt. These sockets are adapted plastic faces are used as is desirable to give a to engage balls . 16 which are carried in holes 45 very light construction the securing may be most
1a in flanged member 80 which is pinned to the readily effected by cementing with fabric bind
shaft 10 at 84.  A disc 82 is urged against the ing strips cemented to the faces to hold them to
flange of the member 89 to confine the balls gether. When assembled the dodecahedron is
under the action of . a spring 84. which bears quite rigid and requires no internal bracing in against the end of the worm 60.. A worm 88 50 addition to the securing of the sides to each
drives the wheel. 12 this worm being carried by other. One of the faces is desirably provided
a shaft 90 which is driven through pulleys 92 with a door  hinged at  and normally
and 96 and belt 94 from a motor 98. closed by a latch  so as to permit access to the
        The motor rotates in a direction to rotate the bulb for replacement thereof.
shaft 26 and the globe which it carries in the 55 The individual pentagonal sides are drilled with
proper direction to. give rise to the diurnal mo pinholes  through which the star images are
tion of the stars. During this motion the drive projected. As pointed out above the relative
is such that the balls 16 are driven by the abrupt brightnesses of the various stars can be effectively
ends of the depressions 14. Since the parts simulated merely by changing the sizes of the driven are light and not subject to any substan 60 pinholes A larger pinhole of course will pro
tial frictional retardation this drive is effectively duce a projected image which is actually larger in
positive in character. Even with the motor run area than that produced from a smaller pinhole.
ping however manual drive may be effected in However in a darkened room the effect of this
either a forward or reverse direction. In either to the eye at a reasonable viewing distance is not case the balls 16 will ride out of the depressions 65 that of difference of size but rather of difference
14 with slightly more difficultly in the reverse of brightness. The holes are drilled at right
direction than in the forward direction but in angles to the planes of the sides and conse
any case due to the yielding action of the disc quently after assembly their axes are not in
82 against the spring 86. A demonstrator may general radial. Nevertheless this does not afaccordingly move the globe either forwardly or 70 feet the results to any appreciable degree when
backwardly at will or by merely holding the the sides are of thin material and a globe such
wheel 64 stationary may hold the globe station as a dodecahedron is adopted.
ary even while the motor continues to run. The In the cases of stars having welldefined colors
reduction gearing may effect„ through the motor the colors may be simulated merely by adhering the drive of the globe at any suitable rate pref 75 on the inside of the globe over the corresponding
2032
A
8
pinholes• stripsof transparent colored cellophane. the ecliptic this arrangement is quite satisfac
Th is is done in the •fashion which will be more tory to attain the degree of approximation of
fully indicated in the later description of the representation for which this device: is intended.
planet projector. The various rings  to I.66 are provided with
If desired there may be marked on the outer 5 openings for the projection of the various planets
surface of the globe lines joining the various the sun and themoon. A preferred arrangement
starsas indicated at i! 2.2 to group these in the of these is with correspondence as follows: Met
conventional fashion as constellations. Such cury  Venus  Jupiter  Sun  Saturn
markingsare of assistance in the study of stars 'Mars 1:64 and Moon . The planet pro
when the globe is viewed in a lightedroom for 10 jeeting holes are similar to those used for the
example beef ore projection takesplace. projectionof the stars and some of these are in
        Besides the pinholes which 'indicate the stars dieated in Figure 12 at •  and I 16 their
there may be provided additional :openings such rings being faced exteriorly with colored cello
as indicated 'in Figure ib 'at . These open phane patches such as indicated at   and
ings which are adapted to be :closed: by flaps  15  to color the projected images to correspond
pivoted at  may serve to identify marking with the colors of the planets. In the case 'of
points such as the •equinoxes. and the :solstices theseringsthe light filters thus providedare de
and serve not only for demonstration of the 10 sirably exterior to avoid their being rubbed off 'as
cation of these points butalso for the setting of the 'rings are adjustedabout the rods .
the planet projector. Normally of course these 20 A large opening  is provided in the ring
openings should be closed. If desired they also to give a'large projected circle simulating thesun.
may be backed with colored cellophane so as to Acircular opening  in the ring  provides
treahetthem readily dentifiable. for the projection of the image of the moon. In
        'The planet projector is indicated at  and this case in order to illustrate the phases of the
is particularly illustrated in Figures 9 to 14 in 25 moon there is provided a metal mask which
elusive. Castings  and  provide the ends of maybe secured invarious positions by a screw
this :projector which is of generally cylindrical passing through openings therein into a
form. Casting it32 is provided with a boss tapped hole adjacent to the opening . This
in which there is drilled at an angle an :opening mask is provided with various crescent openings
for:the receptionof the shaft extension 26' which 30  º1.92  and . As will be obvious from
may Jae secured in position by a set screw . the drawing the mask may be turned end for
This defines the .angle between the axis of the endto show both waxing and waning phases of
planet projector  and the polar axis which is of the moon.
course the angle of 23l'20 corresponding to the Byfreeing the nuts  the various rings may
angle between the plane of the ecliptic and the beset to any relative positions and in particular
plane . Of the . equator. The projection of the to relative positions with respect to the scale
planets gas will shortly be obvious is accordingly which may correspond to those of a particular
in the direction of the plane of the ecliptic. date as shown by astronomical tables. After ad
        The casting 1.38 is provided with a boss  pro jtzstmentthe rings may be clamped in fixed posi
vided with a bushing  in which is adjustably Lion. By the proper adjustment of the lamp
secured by a'set screw  a tube  carrying a any desired approximation for particular bodies
socket for a bulb  which is similar in its char to their relationships to the plane of the ecliptic
acteristics to the bulb 4.0. A lead  serves to may be obtained. However since the device is
provide current to one terminal of the bulb the designed for descriptive rather than quantitative
other terminalof which is grounded. 4S demonstration a considerable latitude of adjust
        The two castings  and  are secured to ment willaffect very little the demonstration. Of
gether by a:series of threaded rods   located course if it is desired to show a precise relation
at their peripheries and serve toclamp a series of ship between a particular planet and a partic
rings between them the clamping pressure on ular star the adjustment of the lamp  will en
which may be relieved by freeing of the nuts . 50 able this to be accomplished.
These rings are indicated at     The setting of the planet projector relativeto
 f and . As indicated in Figure 12 the stellar globe is fixed by the adjustment of the
these rings are shaped at their 'edges so as to in planet projector. about the shaft extension 26'
terlock with sliding bearing on each other and the planet projector being after original adjust
on the outer surfaces of the rods . 55 melt permanently fixed in position by theset
        The •ring  carries on its exterior a scale strip screw i'36 unless change is desired to demonstrate
 which is illustrated in detail  in Figure 37. the precession of the equinoxes. As will be evi
This is provided with markings  indicating dent there are available for setting purposes the
hours and minutes of right ascension and with projections of the equinoxes and solstices from
month 'and day markings . Thescale serves 60 the stellar globe the adjustment of the scale
as a reference for the setting of the planets the about the planet projector and the adjustment
sun and the moon. It may be noted that the al the planet projector about the shaft extension
hours of right ascension are marked on a scale 2.6' .as described. These possible adjustments
which is substantially in the plane of the ecliptic make demonstrable a