A multipotent astrolabe is used to determine the positions of various celestial bodies by applying the circular star atlas and taking into account ephemeral time and the porjections of the relative positions of the moon, the sun and the stars as viewed from the earth. In addition, the positions of the planets of the solar system are included in the multipotent astrolabe to increase the utility of this instrument in the domain of skywatching.

BACKGROUND OF THE INVENTION 
The present invention relates to a multipotent astrolabe or an instrument 
for observing stars, more particularly to a multipotent astrolabe which is 
to improve a rotary star dial and used to determine the positions of 
various celestial bodies by applying the circular star atlas and taking 
into account ephemeral time and the projections of the relative positions 
of the moon, the sun and the stars as viewed from the earth. In addition, 
the positions of the planets of the solar system are included in the 
multipotent astrolabe to increase the utility of this instrument in the 
domain of skywatching. 
Our ancestors, for facilitating the investigation and location of the 
celestial phenomena, developed a lot of instruments such as a chart, a 
list, a disk or a spherical device to determine the relative positions of 
celestial bodies thereon. Through practical operations and experiments 
during the past years, they proved that these instruments were adaptable 
for the simulation or assistance of the astronomical observation. 
A series improvements have been made progressively thereafter. These 
instruments have been embodied a celestial sphere, an armillary sphere or 
a rotary star dial as we have seen nowadays. 
Among the achievements of our ancestors, I find out that the simple and 
partable rotary star dial is worth the effort to further improvements 
incorporation with additional functions in order that a rotatable disk 
shaped instrument can be worked out instead of the above armillary sphere 
to perfectly manifest the relationship among astronomy, geography, 
calendar and time. That's the reason why a multipotent astrolabe has been 
disclosed. 
SUMMARY OF THE PRESENT INVENTION 
The present invention of a multipotent astrolabe provides a complete but 
simple, portable, and low-cost instrument for starwatching. By applying 
the circular star atlas and taking into account ephemeral time and the 
projections of the relative positions of the moon, the sun and the stars 
as viewed from the earth, the multipotent astrolabe is used to determine 
the positions of various celestial bodies. In addition, the positions of 
the planets of the solar system are included in the multipotent astrolabe 
to increase the utility of this instrument in the domain of skywatching. 
The principle of this instrument is based on categorizing the celestial 
bodies. The celestial bodies can be divided into three categories. 
The first category covers the numerous extrasolar stars which are very far 
away and thus their positions in the celestial sphere do not appear to 
change at all during our lifetime. It is easy to determine the positions 
of the stars in the first category. 
The second category covers the sun and the moon. These celectial bodies 
have great profound effects on the earth, such as in the earth's ecology, 
energy resources, day and night alternation, seasonal changes and tides. 
Traditional calendars and calendars of ancient cevilization are all based 
on the relative movements of these two celestial bodies. Hence, it is not 
difficult to determine their positions either. 
The third category of the celestial bodies are the other planets and 
satellites in the solar system besides the sun and the moon. Their effects 
on the earth are not as great as those of the sun and the moon but they 
are the most interesting objects in modern space explorations. Since these 
planets and satellites of the solar system are relatively close to the 
earth, their movements result in great changes of positions relative to 
the earth. There is no simple way commonly used for determining their 
positions. Therefore, it is more difficult to determine the positions of 
these celestial bodies of the third category than the other categories. 
Fortunately, the orbital planes of these planets in the solar system except 
that of Pluto are rather close to the ecliptic plane. (The orbit of Pluto 
is 17.13 degrees inclined to the ecliptic.) The phase angles between these 
planetary orbits and the sun change periodically. Thus, it is quite 
feasible to determine the positions of the planets by using actual models. 
For example, the orbital period of Pluto is 247.69 years and the planet 
only travels 1.47 inches on the surface of the celestial sphere. Uranus 
and Neptune do not seem to move a great distance on the celestial sphere 
either, even though the orbital period of Uranus is 84.013 years and that 
of Neptune is 164.79 years. 
Therefore, it is appropriate and convenient to indicate the positions of 
the planets along their orbits with respect to years. However, for Venus, 
Jupiter, mercury, Mars and Saturn, the orbital radius and revolution 
period are relatively small, the distance of the planetary movement on the 
celestial sphere becomes noticeable even within a few days. 
The planets of the solar system are divided into two groups: the inferior 
planets (Mercury and Venus) which lie closer to the sun than earth and the 
superior planets (Mars, Jupiter, Saturn, Uranus, Neptune and Pluto) which 
orbit the sun at distances greater than that of Earth. 
Disregarding eccentricity and orbital inclination, the relationship between 
the orbit of Earth around the sun and the inner and outer planets is shown 
in FIG. 1, wherein, 
a and b respectively are the semimajor axis of the orbit of another planet 
and Earth. 
Let T be the orbital period of the planet and N be the number of days. 
When an inferior planet is at superior conjunction (that is when it is 
aligned with the sun or at the same ecliptics longtitude as the sun and 
behind it), the phase angle a (that is the angle between the two lines 
formed by joining the centre of the inferior planet to the sun and to the 
earth) becomes zero degree. 
After N days from the time of superior conjunction, as shown in the left 
diagram of FIG. 1. 
EQU Angle c=.pi.-2.pi./T.times.N+2.pi./365.25.times.N 
From the cosin theorem, 
##EQU1## 
From the sine theorem, sin.angle.c/c=sin.angle.b/b 
thus, the alternate angle b observed from Earth between the inferior planet 
and the sun becomes 
##EQU2## 
When a superior planet is at superior conjunction, the phase angle is Zero. 
After N days, as shown in the right diagram of FIG. 1, 
EQU Angle c=.pi.+2.pi./T.times.N-2.pi./365.25.times.N 
From the cosine theorem, 
##EQU3## 
From the sine theorem, sin.angle.c/c=sin.angle.b/b 
thus, the alternate angle b observed from earth between the inferior planet 
and the sun becomes 
##EQU4## 
From these equations, when N is known, the alternate angle between the 
planet and the sun on the ecliptic can be determined. Further, the 
position of the planet can be worked out if the position of the sun is 
known. 
Similarly, on the first day of a month in the luner calendar, the phase 
angle between the line joining the earth to the moon and the line joining 
the earth to the sun is zero. The phase angle can be determined from the 
date in the calendar. Thus, the positions of the moon can be worked out if 
the position of the sun is known. 
The phase angle is subject to periodic change according to the orbital 
period of the celestial body. For the moon, the orbital period is 29.5 
days. For Mercury, 116 days; Venus, 577 days; Mars, 780 days; Jupiter, 399 
days; Saturn, 378 days. Thus, a calendar can be developed based on the 
conjunctive period of each celestial body, such as the luner calendar, 
Venus calendar, Jupiter calendar, etc. Although historically there is no 
known planetary calendar, it is reasonable and feasible to determine the 
positions of a planet based on the solar calendar and the date of 
conjunction (or the date of opposition). 
The coordinates of the celestial sphere follow the curvature of the sphere 
but can be planarized into the coordinates of the star atlas. In fact, the 
coordinates (longitude and latitude) of the earth are interrelated with 
the coordinates (right ascension and declination) of the celestial sphere. 
The terrestrial equator is extended to the celestial equator; the 
terrestrial North and South Poles are extended to the celestial north and 
south poles. When it is possible to planarize the coordinates of the earth 
into a geographic map, it is of course possible to planarize the 
coordinates of the celestial sphere into a celestial atlas. Such a 
planarized celestial atlas can be combined with the geographic map because 
the celestial coordinates are extensions of the terrestrial coordinates. A 
version of this celestial atlas is a planarized celestial sphere with the 
projection of the terrestrial coordiantes to facilitate the determination 
of the position of the celestial bodies with references to the relative 
movements of the earth and the celestial bodies.

DETAIL DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE PRESENT INVENTION 
The northern and southern view as of a multipotent astrolabe are shown by 
FIGS. 2 and 3 respectively. Except the longitudinal retrograde wire 48, 
sliding indicator 50, and polar axis 54, the views are concentric, planar, 
symmetrically connected and revolving around the polar axis for 
determinations with multiple variables. 
The star atlas (FIGS. 4 and 5) centers at the polar hole 2 of the north 
celestial pole and south celestial pole. Based on ecliptic longitude and 
ecliptic latitude, the positions of the stars and constellations 12, the 
ecliptic 8, the celestial equator 10 and the orbits of Uranus 14, Neptune 
16, and Pluto 18 can be located. 
The terrestrial maps (FIGS. 6 and 7), lade of transparent plastic boards, 
also centers at the polar hole 2. With a complete set of longitudinal 22 
and latitudinal 24 lines, the boundaries of land masses and waters can be 
marked. 
The indications of the northern and southern faces of the planetary 
indicating ring (FIGS. 8 and 9) correspond to each other in a fixed 
relationship. Each face of a planetary indicating ring can be fitted 
externally on the star atlas (FIGS. 3 and 4) by means of folding lobes 42. 
The planetary indicating rings and the star atlas are thus concentric. 
Time graduation 26 is marked along the circumference of the planetary 
indicating rings. The position of the sun is indicated by a solar symbol 
28 at the position of noon time on the time graduation. Above the time 
graduation, there are indications of dates in the lunar calendar, symbols 
representing different phases of the moon 30, synodic 32, Mars 36 and 
Saturn 40, and the aberrations 29 of conjunctions in terms of the 
planetary periods of rotation. The positions of the numerals also 
indicates the numbers of days after the planetary conjunctions required to 
obtain the indicated phase angles. 
The fixed latitude observation chart (FIGS. 10 and 11) is made of 
transparent plastic board. The northern and southern latitudinal lines are 
symmetrically joined and combined into a chart. A different chart is made 
for every 5 degrees latitude and thus there are more than different 
charts. These charts are divided into groups of about 15 or more charts in 
each group. Each chart can rotate about the polar hole 2 at its center and 
has an aperture 46 for observing stars. The aperture is manufactured with 
transparent plastic and is drawn by a circle of horizon 43 as observed 
from various longitudinal lines while the other region of the chart beyond 
the aperture is translucent. At the center of the aperture 46, i.e., the 
observer's celestial meridian, the zenith 47 is marked with the 
corresponding azimuth 44 and inclination 45 for determining the positions 
of celestial bodies. Each chart is interchangeable on the multipotent 
astrolabe for use in locations of different latitude. 
Referring to FIGS. 12 and 13, the polar axis 54 goes into the polar hole 2 
for connecting the concentric charts. A longitudinal retrograde wire 48, 
made of spring wire, is bent into two sections. Each section has two 
sliding indicators 50. The end of each section is curved into a holding 
ring 52 and the tip is made into an insertion pin 53. The holding rings 52 
are placed around the north and south polar axis 54 respectively, keeping 
the charts in position. The insertion pins 53 are respectively inserted 
into insert holes 56 of the north and south polar axis 54 for keeping the 
longitudinal retrograde wire 48 in position. 
By rotating the longitudinal retrograde wire 48 and moving the sliding 
indicator 50 along the wire 48, a celestial body can be located in the 
chart. The two sliding indicators are used to avoid repeating the process 
for determining the position of a celestial body by placing one sliding 
indicator 50 on a determined value of phase angle and using the other 
sliding indicator 50 to determine the position of the celestial body. The 
orbits of the moon and planets in the solar system is very close to the 
ecliptic 8. From the position on the chart of the date of periodic 
conjunction of a certain planet or the moon, the phase angle to the sun 
can be determined. A sliding indicator 50 is thus placed on the value of 
this phase angle and the other sliding indicator 50 slides along the 
longitudinal retrograde wire 48, following the other section of the wire 
48 to the other side of the astrolabe if necessary, to the position of the 
ecliptic, which is the position of the planet or the moon in the celestial 
sphere to be determined. 
The operational steps of the multiple astrolabe are described as follows: 
1. Selection of Latitude 
From the terrestrial map (FIG. 6 or 7), first obtain the observer's 
latitude and then select the appropriate fixed latitude observation chart 
(FIG. 10 or 11) for the observer's latitude. For example, an observer in 
Miami, Fla., of latitude about 26 degrees North should select the fixed 
latitude observation chart for 25 degrees North. (If the chart already in 
place is for 25 degrees North, there is no need to change it.) To change 
charts, remove the insertion pin 53 and holding ring 52, replace the 
existing chart by the one selected for the observer's latitude, and put 
back the insertion pin 53 and holding ring 52. The holding rings and 
insertion pins can be easily undone and put chart. It is necessary to 
check that the northern latitude charts are used for the northern view of 
the multipotent astrolabe and southern latitude charts for the southern 
view. 
2. Terrestrial Adjustment 
Place the symbol of the zenith 47 of the center of the aperture 46 of the 
selected fixed latitude observation chart (FIG. 10 or 11) onto the 
terrestrial map (FIG. 6 or 7) at the position of the observer. 
3. Adjustment of Date 
Rotate the planetary ring (FIG. 8 or 9) to place the solar symbol 28 of the 
planetary ring onto the star atlas (FIG. 4 or 5) at the position of the 
date of observation. 
4. Adjustment of Time 
Rotate the fixed latitude observation chart (FIG. 10 or 11) together with 
the terrestrial map (FIG. 6 or 7) to place the northern or southern 
indications which are on the rim of the chart onto the planetary 
indicating ring (FIG. 8 or 9) at the position of the time of observation 
26. If the longitude for a time zone at the observation spot is known, 
rotate the terrestrial map (FIG. 6 or 7) together with the fixed latitude 
observation chart (FIG. 10 or 11) and pinpoint the known longitude to the 
planetary indicating ring (FIG. 8 or 9) in order to indicate the time of 
observation thereon, the result will be greatly accurate. 
5. Adjustment of Direction 
This step is to match the directions on the multipotent astrolabe with the 
actual directions for the observer in the field. The adjust the 
directions, raise the multipotent astrolabe (FIG. 2 or 3) and look up 
through the fixed latitude observation chart (FIG. 10 or 11) to match the 
north and south direction of the chart correctly with the actual 
geographical north and south direction. (The actual geographical north and 
south direction can be found by a compass.) 
After the above five steps are complete, all the sun, the moon, the 
planets, time, calendar and geography are in corresponding condition, more 
like that the sky, the earth, time and space are projected onto this 
little multipotent astrolabe. 
To determine at this time the position of the star Vega (the alpha star of 
the constellation Lyra), first find this star in the star atlas (FIG. 4 or 
5) and place a sliding indicator 50 of the longitudinal retrograde wire 48 
onto the position of this star in the atlas. The position of this star in 
the sky, if shown inside the aperture 46 of the fixed latitude observation 
chart, can be determined by the azimuth 44 and inclination 45 on the 
chart. 
To determine at this time the position of the moon, first look up the date 
in the lunar calendar for today and place a sliding indicator 50 of the 
longitudinal retrograde wire 48 onto the lunar date phase of the moon; 
then move another sliding indicator 50 via the longitudinal retrograde 
wire 48 following the other section of the wire 48 to the other side of 
the astrolabe if necessary, to the position of the ecliptic, which is the 
position of the moon in the celestial sphere to be determined. 
To determine at this time the position of Jupiter, first find out the 
latest date of its conjunction (from one of the reference tables supplied 
with the manual) and determine the aberrations 29 of conjunction on the 
planetary indicating ring (FIG. 8 or 9) by tracing the longitudinal line 
from the solar calendar date of the star atlas. If the aberrations are 
longer than one year, 36.5 periods of 10 days each must be added to the 
number on the planetary indicating ring (FIG. 8 or 9). Find the same 
number on the synodic period 38 for Jupiter and move a sliding indicator 
50 to this position. Then, move another sliding indicator 50 via the 
longitudinal retrograde wire 48, following the other section of the wire 
48 to the other side of the astrolabe if necessary, to the position of the 
ecliptic 8, which is the position of Jupiter at that time. 
Similarly, the positions of Mars, Venus, Mercury and Saturn can be 
determined by this process. As to Uranus 14, Neptune 16 and Pluto 18, 
their orbital positions have for the past several years moved within the 
star atlas (FIG. 4 or 5) and can be obtained directly. 
To determine at this time the local time in New York City, first find the 
position of New York City in the terrestrial map and look up its longitude 
in its time zone which is 75 degrees west; then, following this line to 
the time graduation 26 of the planetary indicating ring (FIG. 8) which is 
the local time of New York City at this time. 
There are many other applications with the multipotent astrolabe such as 
determining in the past or future the position of the sun, moon or star 
from any place on Earth, the time of rise and set of celestial bodies, and 
the time of high and low tide from the positions of the sun and the moon. 
Although planarized indications of inclination and azimuth may not be as 
satisfactory as those in a apherical instrument and the positions of the 
moon and planets may be slightly imprecise owing to eccentricity and 
orbital inclination, the multipotent astrolabe is ideally precise for 
ordinary use. 
Various modification may be lade by those skilled in the arts without 
departing from the essence of the invention as defined in the appended 
claims and their legal equivalents.