Apparatus and didactic method for teaching and showing primary orbital phenomena and various movements

The invention is directed to an apparatus for representing orbital phenomena. It comprises a sphere (20) pivoting about an inclined axis (8) on bearings (38, 60) integral with a support ring (23) mounted adjustable in a slide (26) and locked in the selected position by means of a screw (28), of a local horizon disc (1) pivoting on bearings of the sphere (20), of an ecliptic crown (31) fixed to a ring (21) also pivoting about the globe axis (8), of a drive motoreducer (39) for driving either the ecliptic crown in rotation in the backward direction or the celestial sphere (20) in the direct direction thereby evidencing the referential change and renewing the relationship between apparent motions and real motions. The didactic method implements an observer represented by a figurine (3) placed at the center of the horizon disc (1) itself traversed by the integral axis (8) at 90.degree. of a cardinal axis allowing to sweep during its rotation a virtual plane with a north-south orientation within the ecliptic crown (31). The invention relates to uses of didactic equipment and to the representation of astronomical, physical and chemical phenomena, the professionals concerned by the astronomical phenomena and the periods of sunshine: farmers, architects and town planners, astrologers, chronobiologists, cosmologists, seamen, oyster farmers, landscape-gardeners, marine biologists, etc.

BACKGROUND OF THE INVENTION 
I. Field of the Invention 
The invention pertains to apparatuses and a method to teach and show 
orbital phenomena and various movements studied in astronomy, physics and 
chemistry, and especially for the purpose of explaining and conducting 
experiments on how the relationship between apparent and real movements 
evolves when reference systems are changed, as a function of the 
properties of said reference system and the movements affecting it. 
II. Description of Related Art 
It is known that many armillary spheres propose static and dynamic 
representations of the solar system alone that are not in accordance with 
current astronomic data. It is known that some armillary spheres are more 
faithful to said data, but at the price of conventions and abstractions 
that misconstrue perceptible astronomic data that may be seen by a human 
viewer located somewhere on the surface of the earth (as a first example, 
the earth is reduced to a virtual point located at the center of the 
sphere, with the observer himself being reduced to an eye placed in said 
center; as a second example, the local horizon plane from which the 
observer is supposed to make his observation is by convention represented 
by a flat crown located on the periphery and outside of the sphere, which 
ensures that the terrestrial horizon would be outside of the terrestrial 
globe and even beyond the stars). 
It is known that two-dimensional graphic representations show astronomic or 
physical phenomena, but that these representations are static, and do not 
allow adjustments, predictions or changes in point of view or reference 
system, nor do they allow reversible or progressive instruction. 
It is known that planetariums implement optical mechanisms that allow 
astronomic phenomena to be represented. Unfortunately, said equipment is 
heavy, voluminous, very expensive and merely retrieves stored data. 
On the one hand, the spectator passively watches a set presentation that 
reproduces only phenomena that can be observed in a night sky at a certain 
location on the earth at a given moment, the sky show being generated from 
a precise and thus topocentric horizon; on the, other hand, the spectator 
does not have a more complete, eccentric view of the movements and 
interactions in the solar system that can give him a better understanding 
of astronomy and, furthermore, of physics and chemistry, which 
planetariums do not cover. 
SUMMARY AND OBJECTIVES OF INVENTION 
The apparatus and the didactic method covered by said invention present the 
following advantages: 
Correction of errors and shortcomings in prior didactic machines and 
methods; 
Extension of possibilities for teaching, representing and understanding 
orbital phenomena to scientific disciplines other than astronomy, such as 
physics and chemistry; 
Making predictions and measurements for most astronomic phenomena; 
Changing from a topocentric view of celestial phenomena from the local 
horizon to an eccentric view of the earth on an overall basis, and 
observed, for example, from outside the ecliptic plane; 
Understanding of the earth's rotation and revolving movements seen from the 
earth or from any point in space, in a static or dynamic system, with 
reversible animation giving access to predictions, comparisons, 
verifications, measurements, error and, consequently, personalized 
learning of phenomena considered to date as very dull; 
Reconsideration of the relationship between apparent and real movements 
making it possible to eliminate the isolation between experienced 
astronomy from abstract learned astronomy. 
Practical display of the globe of the earth on the local horizon plane; 
Measurement of the meridian height of a star at any point on earth; 
Measurement of local sun time at any point on the earth; 
Measurement of longitude at any point on the earth; 
Measurement of local sidereal time; 
Definition of the location of sunrise and sunset at any point on the earth; 
Measurement of the local latitude angle; 
Practical representation of sunlight, its angle of attack on the local 
horizon plane and the shadow generated; 
Practical representation of the apparent vertical course of the sun on the 
ecliptic plane; 
Display of the time equation;

DESCRIPTION OF PREFERRED EMBODIMENTS 
FIG. 1 shows a horizon disk whose two north-south and east-west oriented 
diameters define an intersection, which, in this case, is called the 
primordial center, said center being occupied by a humanoid figure in 
standing position and designed to pivot in said center from 0.degree. to 
360.degree. , the periphery of the disk corresponding to the horizon line 
in astronomy. 
FIG. 2. shows an "eccentric" circular ring through which a primordial axis 
PP' passes at a characteristic angle. 
FIG. 3 shows the horizon disk in FIG. 1 surrounded by the eccentric in FIG. 
2, the outside edge of the disk being opposite the inside edge of the 
eccentric. The primordial axis at 90.degree. with the cardinal axis 
included in the horizon disk plane at a characteristic angle with the 
horizon disk pivots around the primordial axis, protruding from the disk 
at both ends and thus scans a north-south oriented plane. 
FIG. 4 represents the virtual primordial axis formed by a first tubular 
shaft, rotating and solidary with the eccentric ring at a point through 
the use of a hoop making it possible to scan around the horizon disk with 
no obstructions. 
FIG. 5 shows a first transparent sphere called an inside sphere 
encompassing the horizon disk in FIG. 1, disk having a cardinal axis whose 
two ends are solidary with said sphere. 
FIG. 6 shows a second transparent sphere known as the outside sphere 
encompassing the horizon plane, the inside sphere and the hoop of the 
eccentric. A second tubular shaft, rotating and solidary with the cardinal 
axis included in the horizon disk, [illegible] line of the axis coinciding 
with the primordial axis allowing the horizon disk to rotate on itself. 
Both shafts thus make it possible to move the eccentric and the horizon 
plane, in a reversible manner or otherwise, and as needed, separately or 
together The access opening to the eccentric and the opening of the inside 
sphere is not visible (after the two openings are aligned, it allows 
adjustment of the latitude angle of the horizon disk and introduction or 
removal of any required signs or objects). 
FIG. 7 shows an example apparatus according to the invention, which, 
through various relative movements, makes it possible to illustrate the 
didactic method developed below. 
It comprises the following: 
A local universal celestial sphere 20 made in two parts 21, 22, of 
transparent plastic material, respectively representing the northern 
hemisphere 21 and the southern hemisphere 22; 
An outside support ring 23, cylindrical in section, to which is welded an 
upper pivot 24 and a lower pivot 25 of primordial rotation axis 8 of 
sphere 20; ring 23 is placed slidingly in a slide 26 solidary with a foot 
27, immobilized using a knurled screw 28 in the position selected for a 
specific observation, northern hemisphere or southern hemisphere, because 
ring 23 makes it possible to reverse the position of the poles; 
A second ring 30, cylindrical in section, acts as a support for a flat 
ecliptic ring 31 made in two half-parts to facilitate assembly, the 
details of which are shown in FIG. 17. Said ring 30 comprises an upper 
bearing 32 and a lower bearing 33 solidary with a pulley 34 making it 
possible to pivot around axis 8; it turns in its lower part on a shaft 35 
engaged at its upper part in a bearing 36 fixed to sphere 20 along axis 8, 
its lower part 37 pivoting in a bearing 38 welded to ring 23. 
A back-geared motor 39, on whose outlet shaft is mounted a pulley 40, 
drives pulley 34 in rotation by means of a belt 41 engaged in the 
corresponding groove of pulley 34. Said back-geared motor is attached to a 
support 42 welded to support ring 23; back-geared motor 39 makes it 
possible to drive either the ecliptic in the backward direction, or 
celestial sphere 20 in the forward direction in rotation by crossing belt 
41 on the pulleys or reversing the rotational direction of the back-geared 
motor, in cooperation either with a fastening screw 43 screwed into 
bearing 33 to drive the ecliptic in rotation, or a screw 44 screwed into 
bearing 36 of sphere 20 to drive it in rotation. 
As shown in FIGS. 8 and 9, the immobilization of the sphere during the 
rotation, motorized or otherwise, of the ecliptic ring, or, conversely, by 
loosening said screws, makes it possible to turn sphere 20, while the 
ecliptic ring is immobile, which shows the difference between the real and 
apparent daily and annual movements of the sun. In this way, ecliptic 
crown 31 is made movable for the topocentric observer located at the 
primordial center of the local horizon disk, and the ecliptic crown is 
immobilized for the eccentric observer, and, by loosening screws 47, 48, 
the small ball 50 (FIGS. 8 and 9) representing the globe of the earth is 
made movable by turning the sphere. Said inversion will be more clearly 
understood with the supplementary apparatus shown in FIGS. 26 and 27. 
A horizon disk 1 shown on pivots 45, 46 each engaged in a corresponding 
bearing of sphere 20 whose rotation axis XX' embodies the east-west axis 
(FIGS. 8 and 9); the end of the pivots is threaded and each receives a nut 
button 47, 48 to control the disk inside sphere 20; a ribbon 49 made of 
transparent semi-rigid plastic material is fastened in a hoop against the 
north/south edges of disk 1 at right angles with the local meridian traced 
on the sphere, said ribbon 49 being graduated in latitude; 
A small sphere 50 representing the earth is attached under local horizon 
disk 1 to the primordial center; the local horizon disk is tangent to said 
terrestrial sphere at a point whose latitude can thus be located visually 
using the north pole-south pole axis represented here by the primordial 
axis; 
As shown in FIGS. 7 and 12, a longitude selection index 55, attached to the 
base of a tube 56 is engaged in upper bearing 57 of sphere 20 and in upper 
bearing 32 of ring 30, index 55 is oriented through the use of a small 
handle 58 whose end is screwed into an inside threading of tube 56 
pressing against the top of bearing 57. A hollow axis 59 acting as a pivot 
is engaged in a bearing 60 welded to the inside of support ring 23; said 
ring 23 is open to allow pivot 59 to pass. Said arrangement simplifies the 
assembly of the ecliptic sphere/ring unit. Pivot 59 is locked on bearing 
60 using a screw 61; a second screw 65 locks sphere 20 in cooperation with 
handle 58 locking pivot 59 to tube 56. A spring 62 was placed at the 
bottom of tube 59 to allow the pivot to be extracted if it is necessary to 
disassemble the sphere. 
A straight shaft 66, passes through tubular body 56 of the index and moves 
forward to the primordial center. For the local observer, said shaft 
embodies the axis of the world, the direction of the polaris star and the 
latitude angle of the area formed between said shaft and the south/north 
direction traced on local horizon disk 1. 
FIG. 10 shows a mechanism to measure local sun time embodied by three 
parallel circles traced on sphere 20, in this case, known as 
beginning-of-season circles, graduated into 24 equal parts (FIG. 11) 
indicating the times based on the local meridian: for example, a yellow 
circle 71 placed perpendicular to the primordial axis of the equator of 
the sphere, representing the local celestial equator as well as the 
trajectory of the sun during equinoxes [sic]. Said circle is graduated 
into 24 hours; 
On both sides of said first circle, at 23.degree.30' and parallel thereto, 
a red circle 72 was traced representing the trajectory of the sun during 
the summer solstice for the northern hemisphere and a blue circle 73 
representing the trajectory of the sun during the winter solstice for the 
northern hemisphere. On these three circles, the hours are interconnected 
by 24 segments 74 of time circles perpendicular to the first three 
circles, yellow, blue and red. The time grid thus formed makes it possible 
to read the local sun time regardless of the latitude, day and the month 
of observation because the trajectory of the sun always cuts said grid. It 
primarily makes it possible to predict the rising and setting times of the 
sun, the moon and all of the planets in the solar system, regardless of 
the present, past or future time It makes it possible to find the length 
of the day and night immediately at any location on the earth and at any 
time. It also makes it possible to define where on the earth and on what 
dates it will be daylight for 24 consecutive hours or more. 
The time equation has been traced on the sphere in the form of an infinity 
sign analogous curve between circles 72 and 73 of the two solstices, 
overmounting the local horizon meridian. Said curve gives a practical view 
of the difference between mean solar noon and true solar noon, i.e., to 
predict when the sun is ahead or behind in passing the local horizon 
meridian in comparison with legal mean noon. 
FIG. 11 shows the mechanism for measuring and showing local sidereal time. 
This is characterized by 24-hour graduations of the celestial equator 
(yellow circle) with a color other than the one used above for reading 
solar time. Said measurement is made by the correspondence of said 
graduation with a GAMMA index drawn on the zero degree of the ecliptic 
crown. 
FIG. 12 shows a mechanism that makes it possible to select the longitude of 
the place of observation. Graduations 75 have been drawn on sphere 20 
around the north pole, 180.degree. EAST and 180.degree. WEST. Index 55 
(FIG. 12) placed against the inside wall of sphere 20 solidary with its 
adjustment tube 56 placed on the primordial axis is designed to be 
immobilized using a screw 65, either on the local meridian or on the 
Greenwich meridian. Said device makes it possible to measure the time 
difference between two points on the earth selected at will. 
FIG. 13 shows the graduations indicating the latitude on the local 
meridian, identified in north latitude and south latitude. 
FIG. 14 shows the ecliptic crown 31 from a top view graduated into twelve 
equal divisions from 0.degree. to 360.degree. and bearing the 
characteristic dates of the sun's position as well as the GAMMA point or 
equinox point, together at 0.degree.. 
FIG. 15 is a detailed view of the curve defining the time equation, whose 
position on sphere 30 is represented in FIG. 10. The time equation varies 
little from one day to the next. It is canceled out four times per year, 
on Apr. 15, Jun. 14, Sep. 1 and Dec. 25. The greatest differences between 
mean noon and true noon are observed on Feb. 11 and Nov. 3, when they are 
respectively +14 mn 23' and -16 mn 22'. 
FIGS. 16, 17, 18 and 19 show a ring 80 which precisely reports lunar 
movements. This is done through the use of a tube cut into two equal parts 
81, 82 each welded in the center to a small U-shaped slide 83 engaged on 
the inside edge of ecliptic crown 31, along an angle 84 of approximately 
5.degree.. The two half-parts of tubular ring 80 are secured together by 
two small pins 85, for example, made of plastic material, engaged in the 
ends opposite each other (FIG. 19). Ring 80 cuts ecliptic crown at two 
points 86, 87 which form lunar nodes and whose positions can be adjusted 
at their own rate. 
Said device allows a precise tracking of the movement of the moon through 
the sky and prediction and display of the eclipse mechanism. Said 
information is important, especially in biodynamic agriculture and for 
calculating tides (tides are theoretically high when the moon passes over 
the meridian of the location. Spring tide periods take place when the moon 
and sun are either in conjunction or in opposition, i.e., at 180.degree.; 
neap tide periods occur when the moon and the sun are in quadrature, i.e., 
at 90.degree. angles with each other). 
FIG. 17 also shows an example of the assembly of the two parts of the 
ecliptic crown on support ring 23, using at least one sleeve 86 comprising 
a bore 87 whose diameter takes into account the curvature of the ring to 
which it is engaged before the bearings are welded, a wide support head on 
the top of crown 31 and a threaded bearing area 88 engaged in two 
half-holes of the two parts of the crown, assembled using a washer 89 and 
a nut 90. 
FIG. 20 shows a mechanism to define, at any place on the earth, the 
location of the "rising and setting" of the sun and any of the stars in 
the solar system. For said purpose, graduations 92 have been drawn in 
degrees on the periphery of local horizon disk 1. Measurement is done in 
north or south degrees azimuth 
FIGS. 20, 21 and 22 show a mechanism to display the duration of twilight at 
any location on the earth and at any time, characterized in that horizon 
disk 1 is endowed with a thickness on which is traced several circles 
parallel to the surfaces of the disk, in this case, known as twilight 
circles. The intersection of the horizon circle with the time grid 
indicates the onset of twilight; the intersection of a selected twilight 
circle yields the end of the corresponding type of twilight: civil, 
astronomic, nautical. The trajectory of the sun is provided as an example 
in thick lines: The trajectory 95 of the sun at the equator is vertical; 
the transition from day to night at that location is consequently very 
short, approximately 15'; in Example 96, the sun's trajectory is inclined 
60.degree., and the length 97 of the twilight is relatively long; 
gradually as its trajectory inclines 98, length 99 increases. Said 
arrangement makes it possible to show clearly and understand said concept, 
which is difficult to perceive in abstract terms. 
FIG. 23 shows a mechanism for displaying the ascending and descending 
movement of the sun in the meridian plane every day at noon throughout the 
entire year. Said mechanism consists of a small ball 102 sliding on 
support ring 23 of the primordial axis of sphere 20 placed concentrically 
with and outside of the local horizon meridian, and rolling on ecliptic 
crown 31. Said movement makes it possible, in a single rotation of the 
ecliptic crown, to display the rising and setting movement of represented 
by ball 102 between the two solstices (circles 72, 73 FIG. 10) and to 
pinpoint the precise moment and point at which the sun changes direction 
on its annual course. The small ball 102 is preferably made of plastic 
material in two parts 103, 104 (FIG. 24) held together by two slugs 105 
shrunk by force into one of the two parts and fastened to the second to 
facilitate their positioning. FIG. 25 shows a device to illustrate the 
concept of day, night and the seasons. Said device consists of placing a 
localized light source 110 representing the sun on the inside edge of the 
ecliptic crown 31. It consists of a small electric bulb fed by a small, 
adequate and interchangeable electric battery placed in a housing 111 made 
of plastic material. Said housing comprises a slide 112 fastened with 
slight pressure to the inside edge of the crown of ecliptic 31, said slide 
making it possible to move the "sun" over the entire length of said crown. 
When said light source is above horizon disk 1, and sheds light on it, it 
is "DAYTIME;" when said source is occulted by the horizon disk, it is 
"NIGHTTIME;" it remains above the horizon disk for longer or shorter 
periods; it is higher or lower, which provides a practical illustration of 
the concept of the seasons. 
Said light source faithfully reproduces the shadows generated by the sun 
and their evolution throughout the day and during the year. It makes it 
possible to read the local sun time on a sun dial placed at the primordial 
center of the device, according to the shadow produced by said source. 
Moreover, the comparison between the real shadow produced by the sun at 
time "t" and the shadow produced by the light source of the apparatus 
makes it possible to determine the date and time, or the latitude and 
place of observation. 
FIGS. 26 and 27 show a means of simultaneous representation either of real 
movements (seen exocentrically), i.e., the rotation of the earth around 
its axis in 24 hours and the revolution of the earth around the sun in one 
year, or apparent movements (seen topocentrically), i.e., the path of the 
sun around the earth in 24 hours and the path of the sun on the ecliptic 
in one year. 
It comprises a support plate 115 on which two shouldered axes 116, 117 have 
been mounted, one YY' showing the position of the earth and the other ZZ' 
showing the position of the sun; each of said axes comprises a threaded 
bearing surface 118 to which is screwed to the root of the threading 
handles 119, 120 leaving a slight clearance between plate 115 and handle 
119, 120, allowing them to rotate. Axes 116, 117 each comprise a bearing 
surface 122 to which is engaged a rounded-groove pulley 123, 124 locked in 
rotation by a screw 125 endowed with a large head wherein a milled groove 
serves as a guide for a half-ring 126 to which a second ring 127 
representing the ecliptic is welded; to the base of half-ring 126 is 
welded an axis 128 endowed with a bearing surface engaged in a hole placed 
in pulley 123 inclined along primordial axis 8, said axis containing a 
hole acting as a bearing for an axis welded under a ring 130 supporting an 
equatorial ring 131 perpendicular to primordial axis 8 on two hinges from 
which a local horizon disk 132 pivots. 
Pulleys 123, 124 are driven in synchronism by a belt 134. Pulley 124 is 
made unitary with axis 117 by a screw 136 whose head 137 is extended by a 
shaft 138 the free end of which accommodates a small ball 139 representing 
the sun, fastened to a shouldered bearing surface 140. Shafts YY' and ZZ' 
are spaced so that small ball 139 representing the sun moves close to 
ecliptic ring 127. Plate 115 protrudes on each side beyond the pulleys 
through handles 142, 143. When vertical handle 119 is held while pushing 
on handle 143, the apparent movement of the sun revolving around the earth 
is observed. When vertical handle 120 is held while pushing on handle 142, 
the real movement of the earth around the sun is observed. Said method of 
representation makes it possible to understand how apparent and real 
movements reverse when the reference system (topocentric or exocentric) is 
changed. 
Said method also demonstrates the fact that the earth's axis 8 remains 
parallel to itself while the earth revolves around the sun, which is a 
highly abstract phenomenon that defies any dynamic representation. 
As mentioned in the description of FIG. 7, to facilitate the observation of 
astronomic phenomena that can be observed in the southern hemisphere, 
support ring 23 slides in a slide 26 wherein it can be locked in any 
position for the purpose of orienting the entire device along the most 
favorable angle for the users. The most favorable angle, for example, for 
an exocentric observer watching the earth rotate on itself corresponds to 
the horizontal and immobile ecliptic crown. The device makes it possible 
to observe the progressive passing from the northern hemisphere to the 
southern hemisphere and to display the progressive transformation of the 
manifestations of the different celestial phenomena, in their form as well 
as in the areas in which they occur, for example, the reversing of 
different lunar phase figures, constellations of the zodiac, the rising 
and setting of different stars. 
The didactic method for teaching and displaying orbital phenomena and 
various movements studied in astronomy, physics and chemistry utilizes a 
local horizon plane of the planet or the secant plane of the nucleus 
formed by a local horizon disk 1 whose periphery corresponds to the 
horizon line (2) that can be seen by an observer located in its center, 
said "topocentric" observer being advantageously embodied by a humanoid 
figurine (3) in standing position and able to pivot 360.degree. on itself. 
The primordial center 4 of said disk 1 is embodied by the intersection of 
the two perpendicular diameters whose ends shown on the disk indicate the 
orientation, for example, of the cardinal points: north-south; east-west. 
Said horizon disk is designed to accommodate signs, graphics or objects 
embodying astronomic or topographic concepts such as azimuth graduation, 
the meridian of the location, compasses, the celestial equator or physical 
and chemical concepts such as the nucleus, electron, etc. The ecliptic 
crown (31) may further be made of a material allowing figurines of stars 
to slide on its inside edge. The didactic method gives the student the 
ability to change observation reference systems, i.e., on the one hand, to 
identify with the aforementioned figurine and place himself in the 
position of an observer of the phenomena shown in the celestial, physical 
or chemical visual field, above the local horizon plane, and, on the other 
hand, not to identify with said figurine so as to have access to a 
different view of the system studied. 
The didactic method advantageously uses an orbital plane embodied using an 
"eccentric" circular ring 5 distinguished by its inside edge 6 
representing an orbit, for example, the ecliptic, and located opposite 
outside edge 7 of horizon disk 1, distinguished by the ability of said 
ring to be endowed with various signs or objects representing celestial 
bodies, nuclei, electrons, particles, or scientific information such as 
the equinox point, graduations, signs of the zodiac, etc., distinguished 
finally by the ability of said ring to become unitary with either a flat 
crown more broadly representing the orbital plane (for example, the plane 
of the ecliptic); with a full sphere advantageously holding stars, 
electrons, particles, etc.; or with a spherical zone representing a 
segment of a sphere (for example, the zodiac strip in a celestial sphere). 
Said zodiac strip is preferably made of transparent plastic material 
mounted on the outside edge of ecliptic crown 31 using a slide 86 (FIG. 
17). The relative movement of said strip around the crown occurs in 26,000 
years and shows the staggering of the zodiac signs with the constellations 
of the same name. 
The didactic method advantageously uses a first virtual axis called 
primordial axis 8PP' corresponding, for example, to the earth's axis in 
astronomy, distinguished by the fact that it passes through the center of 
eccentric ring 5 forming a fixed angle characteristic of the initial 
location of topocentric observation, for example, an angle of 
66.degree.30' for an observer located on a terrestrial horizon plane), 
distinguished by the fact that it passes through the center of horizon 
disk 4 forming an angle that can be varied and adjusted as needed, and 
which always remains within the plane perpendicular to the horizon disk 
along the north-south orientation line, distinguished by the fact that the 
center of eccentric ring 5 and the center of horizon disk 4 coincide on 
it, distinguished by the fact that it indicates in sense P the direction 
of the north-south pole (for example, the north celestial pole shown by 
the polaris star). 
The didactic method advantageously uses a second virtual axis known as 
cardinal axis 9, distinguished by the fact that it is contained in the 
horizon disk and that it coincides with the east-west orientation line of 
the same disk, distinguished by the fact that primordial axis 8 is 
perpendicular to it, that their intersection coincides with primordial 
center 4, and that horizon disk 1 can pivot around it, just as with 
primordial axis 8. 
The didactic method advantageously uses a meridian plane of the horizon 
disk embodied by the scanning of the line of primordial axis 8 in its 
rotation around the line of cardinal axis 9. The didactic method 
advantageously uses the latitude of the horizon plane (for example, of the 
local horizon plane in astronomy) embodied by the angle formed by the line 
of the primordial axis with the north-south orientation line of the 
horizon disk. 
In the didactic method, eccentric ring 5 can to be used as a track for the 
orbital displacement of various bodies such as electrons, or, for example, 
the sun, moon and planets in astronomy. 
The didactic method advantageously uses a virtual spherical zone embodied, 
for example, through the scanning of the aforementioned eccentric ring 
during a rotational movement around the primordial axis, thus offering the 
topocentric and immobile observer 3 on horizon plane 1, itself immobile, 
the representation of orbital movements, for example, revolution movements 
of the planets shown on eccentric ring 5 making it possible, for example, 
to use said method in astronomy to show the phenomenon of day, night and 
the seasons. 
The didactic method advantageously uses a partial occultation of eccentric 
ring 5 obtained by the scanning of horizon disk 1 during its rotational 
movement around primordial axis 8, making it possible, for example, to 
represent the phenomenon of day and night in astronomy at any location and 
during any season. 
The didactic method advantageously uses a first transparent sphere known as 
inside sphere 10 which encompasses horizon disk 1 whose diameter is almost 
equal to that of the sphere, horizon disk 1 thus encompassed having a 
cardinal axis 9 whose two ends 11 are unitary with said sphere 10. Virtual 
primordial axis 8 of the inside sphere is embodied by a first tubular 
shaft 12, rotating and solidary with eccentric ring 5 in at least one 
point, using any means allowing the unobstructed scanning around the 
horizon disk (for example, one or more hoops 13). 
A second rotating tubular shaft 14 solidary with cardinal axis 9 included 
in horizon disk 1 and whose axis line coincides with primordial axis 8 
allows the horizon disk to rotate on itself, inside sphere 10 possibly 
being endowed with an opening making it possible to use any means to 
adjust the latitude angle of horizon disk 1 and to introduce or remove any 
required signs or objects. 
The didactic method uses a second transparent sphere known as the outside 
sphere 15, which encompasses the first sphere 10 having a larger allowing 
the free internal rotation of at least one eccentric ring 5. The first and 
second aforementioned rotating tubular shafts protrude outside of sphere 
15 with optional double, simultaneous or independent setting into motion. 
The outside wall of the outside sphere can, in a temporary of permanent 
manner, be endowed with any required sign or object and may be endowed 
with an opening that can advantageously be aligned with the opening of the 
inside sphere, making it possible to use any means to adjust the latitude 
angle of the horizon disk and to introduce or remove any required sign or 
object, with respect to the inside sphere or one of the eccentric rings. 
The outside sphere may advantageously be replaced with a support ring 23 
holding the bearings of primordial axis 8. 
The didactic method according to the invention makes it possible to teach 
and to represent in a progressive or degressive, static or dynamic, or 
even reversible manner, numerous orbital phenomena and various movements 
studied in astronomy, physics and chemistry. It makes it possible to make 
forecasts, verifications and corrections of errors; orbital phenomena can 
appear using manual or motorized animation, or can be immobilized in 
static position. 
The didactic method according to the invention primarily concerns the 
manufacturers and users of didactic materials and representations of 
astronomic, physical and chemical phenomena, as well as various 
professionals dealing with astronomic phenomena: farmers, sailors, 
chronobiologists, astrologers, etc., and those who deal with sunshine 
architects, urban planners, landscaper gardeners, cosmologists, 
thalassotherapists, oyster growers, etc.