Patent Publication Number: US-8995233-B2

Title: Astronomical watch

Description:
This application claims priority from European patent application no. 12191477.4 filed Nov. 6, 2012, the entire disclosure of which is incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The invention concerns a mechanism for displaying the day and the phase of at least one celestial body, comprising a gear train for a constant frequency gear drive on an output of a timepiece movement, said mechanism including a means for the three-dimensional display of the day and the phase of said first celestial body symbolised by a first mobile component, said means being driven by said gear train, which includes a phase train and a day train, each in mesh on an output of the same said movement. 
     The invention also concerns a movement including a drive means for driving at least one such display mechanism. 
     The invention also concerns an astronomical watch including at least one movement of this type, and/or at least one mechanism of this type. 
     The invention concerns the field of mechanical horology, and in particular, complications for displaying the state of certain celestial bodies. 
     BACKGROUND OF THE INVENTION 
     Astronomical watches are among the watches with complications appreciated by users. Their accuracy is often approximate as regards the display of the cycles of certain celestial bodies, in particular lunar cycles, often because of the small volume available inside the movement, which generally cannot house the large number of wheels which would be necessary to ensure an accurate estimate of the duration of the lunar day and month. 
     Further, it is often impractical to view the celestial body phases. Most timepiece displays have abandoned the illustration of the celestial body day. 
     WO Patent No 91/11756 A1 in the name of Richard discloses a Moon display with a first circular plate whose rotation is maintained by a drive mechanism of the watch, with a sphere representing the Moon, able to be moved with this circular support along an aperture arranged in the watch dial. The drive mechanism includes a means of driving the circular support in rotation relative to the aperture, at a speed in keeping with the speed of the apparent movement of the Moon in the sky between rising and setting. The mechanism drives in rotation a second plate at a similar speed to that of the first plate, the second plate drives a pinion which causes the sphere to turn about an axis parallel to the watch dial. 
     The technical article of the  Jahrbuch der deutschen Gesellschaft für Chronometrie , in the name of GLASER &lt;&lt;Astronomische Indikationen bei Uhren&gt;&gt;, published on 1 Jan. 1989, vol. 40, pages 139-161, XP000102620, ISSN 0373-7616, discloses a representation of the Moon phases by means of a rotating sphere or rotating discs. A differential drive element drives at suitable speeds both the sphere in rotation on its arbour, and the arbour relative to the dial. 
     U.S. Pat. No. 3,766,727A in the name of DIDIK discloses a planet clock with a complex gear train driving the planets of the solar system represented by spheres, with the Moon pivoting about the Earth mounted on an inclined arbour, and wherein the driving of the inclined Earth arbour, the Earth about the arbour, and the Moon about the Earth, is performed by as many pulleys in mesh with axial cannon-pinions of the movement. 
     FR Patent No 12 679 052 A1 in the name of GHIRIMOLDI discloses a planetarium timepiece mechanism with a solid representation. 
     FR Patent No 348 040 A in the name of Burke discloses an astronomical clock with some celestial bodies motorised with respect to others. 
     SUMMARY OF THE INVENTION 
     The invention proposes to integrate a visual indication of the day of a celestial body into a watch, in particular the lunar day, simultaneously with the display of the phase of said celestial body. 
     It is an object of the invention to ensure both great accuracy as regards observing astral periods, and very good visibility via a three-dimensional display, which is attractive to the user. 
     The invention therefore concerns a mechanism for displaying the day and phase of at least a first celestial body, comprising a gear train for a constant frequency gear drive on an output of a timepiece movement, said mechanism including a means for the three-dimensional display of the day and phase of said first celestial body represented by a first mobile component, said means being driven by said gear train, which includes a phase train and a day train, each in mesh on an output of the same said movement, characterized in that said phase train, and/or the day train, includes at least one uncoupling means between the input and output thereof. 
     According to another feature of the invention, said phase train and the day train each include at least one uncoupling means between the input and output thereof. 
     According to a feature of the invention, the uncoupling means of said day train includes a jumper spring arranged between, on the one hand, a day wheel kinematically connected to the input train from said movement, and on the other hand, a wheel with male wolf teeth, arranged to be driven by said phase train and to cause said first mobile component to pivot. 
     According to a feature of the invention, the uncoupling means of said phase train is formed by the cooperation between, on the one hand, a cam disposed on the periphery of a snail arranged to be driven by an intermediate wheel which is kinematically connected to the input train from said movement, and, on the other hand, the first arm of a lever; said first arm is returned by an elastic return means towards said cam, and the jump thereof on a slope of said cam causes the rotation of said lever and the movement of a second arm which is comprised therein and which carries a click, arranged to cooperate with said day train and move said train forward one position at the time of said jump. 
     According to a feature of the invention, said snail is not permanently driven by said intermediate wheel, which carries a toothing with female wolf teeth; said snail carries a click arranged to make the snail pivot integrally with said intermediate wheel, and the jump of said first arm of said lever on said slope of said cam releases said click from said female wolf toothing prior to the re-engagement thereof in position in the next tooth. 
     According to an alternative feature of the invention, said snail pivots integrally with said intermediate wheel. 
     The invention also concerns a movement including a drive means for driving at least one such display mechanism. 
     According to a feature of the invention, said movement includes a day/night drive mechanism and/or a GMT mechanism, for driving at least one mobile component representing a celestial body and/or a semi transparent globe covering one said mobile component. 
     The invention also concerns an astronomical watch including at least one movement of this type, and/or at least one mechanism of this type. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the invention will appear upon reading the following detailed description, with reference to the annexed drawings, in which: 
         FIGS. 1 to 6  are schematic views of a first variant of the celestial body day and phase display mechanism according to the invention. 
         FIG. 1  is a perspective view of the mechanism alone. 
         FIG. 2  is a front view of the mechanism alone. 
         FIG. 3  is a bottom view of the mechanism alone. 
         FIGS. 4 and 5  are respectively right and left side views. 
         FIG. 6  is a front view of the mechanism behind a screen in the position in which it is visible to the user. 
         FIG. 7  shows a schematic, perspective view, similar to  FIG. 1 , of a second variant of the invention, shown with the screen of  FIG. 6 . 
         FIG. 8  shows a partial, schematic, front view of an astronomical watch including a three-dimensional Moon display according to the invention. 
         FIG. 9  shows the watch of  FIG. 8  in a view from the right. 
         FIG. 10  shows a front view of a variant of the invention with the simultaneous representation of the Earth and the Moon both movable in plane. 
         FIGS. 11 to 13  show cross-sections of particular variant representations of celestial bodies in the form of a sphere covered by a globe including a transparent hemisphere and a dark hemisphere, and various possible settings. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The invention concerns an astronomical timepiece, particularly an astronomical watch, and more specifically a display mechanism for showing the state of at least a first celestial body, whether this is the Earth, a moon or other body. 
     The invention more specifically concerns the three-dimensional display of the day and phase of a celestial body. The “phases” of a celestial body are, with the exception of the Sun, the successive orientations adopted by the celestial body illuminated by the Sun, where the celestial body is viewed from Earth. In the case of a “planetarium” type timepiece or astronomical clock grouping together the various planets of the solar system and some of their satellites, the phases of these various planets and satellites are viewed, not from the Earth, but from a point in the solar system which is remote from Earth. As a general rule, in this description, the term “celestial body” designates planets and satellites, with the exception of the Sun. 
     The invention concerns a mechanism  1  displaying the day and phase of at least a first celestial body, comprising a gear train  2  for a constant frequency gear drive on an output of a timepiece movement  100 . 
     The “day” of a celestial body means here the period during which the body pivots on itself and returns to the same visible position with respect to a fixed observer on the Earth. 
     The “month” of a celestial body means a synodic revolution, i.e. the mean value of the time interval which separates two consecutive conjunctions of the celestial body and the Sun, moments where said body and the Sun have the same celestial longitude, relative to a fixed observer on Earth. 
     With regard to the Earth, the day and month are to be understood in their normally accepted sense: the 24 hour day is the mean solar day defined by the International Convention of 1955 (in the knowledge that the sidereal solar day is close to 23 hours and 56 minutes, the difference between the true solar day and the sidereal day varying between 3 minutes and 36 seconds, and 4 minutes 26 seconds). 
     By convention, an element of the mechanism relating to the display of the first celestial body will be termed “first”; an element relating to a second celestial body will be termed “second” and so on. 
     According to the invention, this display mechanism  1  includes a means  3  for the three-dimensional display of the day and phase of the first celestial body represented by a first mobile component  5 , which is driven by gear train  2 . 
     In a preferred embodiment illustrated in the Figures, this three-dimensional display means  3  includes a first phase arbour  4 , directly or indirectly pivotally driven by gear train  2 . 
     This first phase arbour  4  carries a first mobile component  5 , particularly a first sphere  5 , which simulates the first celestial body, and which makes one revolution whose period is the duration of one month of the first celestial body. 
     A “sphere” hereafter means a mobile component representing a celestial body, 5 or 50, regardless of the actual shape of the mobile component. 
     Mechanism  1  includes a first day arbour  6 , directly or indirectly pivotally driven by gear train  2 . The first mobile component  5  or sphere  5  makes one revolution about this first day arbour  6  on an orbit whose period is the duration of one day of the first celestial body. 
     Gear train  2  advantageously includes a phase gear train  10  and a day train  20 , each in mesh on an output of the same movement  100 , for example on the cannon-pinion or on a twenty-four hour wheel. Phase train  10  and day train  20  may be driven by different outputs of the same movement, or one by the other or may each drive the other. 
       FIGS. 1 to 6  illustrate a first variant of a mechanism  1  wherein the first day arbour  6  is pivotally driven by a day train  20 , directly or indirectly, from one output of movement  100 . The first phase arbour  4 , pivoting about an axis D 4 , is pivotally driven by a phase train  10 , directly or indirectly from an output of movement  100 . 
     Advantageously, phase train  10  and/or day train  20  includes at least one uncoupling means between its input and its output. Preferably, phase train  10  and day train  20  each include at least one uncoupling means between the input and output thereof. 
     In the particular preferred embodiment, the first phase arbour  4  is carried by the first day arbour  6 , or by a phase mobile component  7  driven by said first day arbour  6 . 
     Day train  20  includes an input wheel  21 , in mesh with a twenty-four hour wheel of the movement, or with an intermediate wheel imparting a twenty-four hour rotation thereto, and corresponds to the duration of the mean solar day. If necessary, input wheel  21  meshes with an intermediate wheel  22 , which engages with a first celestial body day wheel  23 , or it meshes directly with said first celestial body day wheel  23 , according to the required gear reduction, with said wheel  23  completing one revolution in one first celestial body day. First celestial body day wheel  23  is pivotally mounted, about a pivot axis D 6 , coaxially with a wheel having male wolf teeth  24 . Wheels  23  and  24  are connected to each other by a jumper spring  25 ; action on wolf toothing  24  may uncouple this mechanism and modify their relative angular position. The uncoupling means of day train  20  thus includes this jumper spring  25  arranged between, on the one hand, a day wheel  23  kinematically connected to the input train from movement  100 , and, on the other hand, a wheel with male wolf teeth  24 , which is arranged to be driven by the phase train  10 , and which pivotally drives the first mobile component  5 . 
     Wheel  24  carries the first day arbour  6 , which includes a frontal pinion  26 . 
     This frontal pinion  26  meshes with a wheel  27  integral with the first phase arbour  4 . 
     Phase wheel  10  includes an input pinion  11 , in mesh with the cannon-pinion of the movement, or with an intermediate wheel which imparts a one hour rotation thereto. Pinion  11  meshes, where necessary, with an intermediate wheel  12 , which engages with an intermediate wheel  13 , which makes one revolution in a given period, or meshes directly with said wheel  13  as illustrated in  FIG. 1 , according to the desired gear reduction. 
     This intermediate wheel  13  comprises an inner set of wolf teeth  14 . 
     A snail  15  pivots coaxially with intermediate wheel  13  about an axis D 1 , the periphery  15 A thereof forms a cam  16  having a slope  16 A delimiting a beak  16 B, and having a click  17  with a single tooth which pivots on a pivot  17 A and which cooperates with inner toothing  14 , as seen in  FIG. 2 . 
     A runner  18 , particularly a ruby, covers the periphery  15 A of snail  15 , and is carried by a lever  19 , pivotably mounted about an axis D 9  relative to the bottom plate of movement  100 , and a first arm  19 A of which, carrying runner  18 , is returned towards snail  15  by a spring (not shown in the Figures). 
     When, once per revolution of intermediate wheel  13 , runner  18  passes from the high point of snail  16  to the low point, passing over beak  16 B and slope  16 A, it releases click  7 , whose tip then takes up the hollow of the next tooth of female toothing  14 . 
     Thus, the uncoupling means of phase train  10  comprise, on the one hand, a cam  16  disposed on the periphery  15 A of a snail  15  arranged to be driven by intermediate wheel  13  which is kinematically connected to the input train from movement  100 , and on the other hand, the first arm  19 A of a lever  19 , said first arm  19 A is returned by an elastic return means towards said cam  16 , and the jump thereof on a slope  16 A of the cam causes the rotation of lever  19  and the movement of a second arm  19 B which is comprised therein, and which carries a click  19 C, arranged to cooperate with the wolf teeth wheel  24  of day train  20  and move said train forward one position at the time of said jump. 
     In this first variant, snail  15  is not permanently driven by intermediate wheel  13 , which carries a female wolf toothing  14 ; snail  15  carries a click  17  which causes it to pivot integrally with intermediate wheel  13 , and the jump of first arm  19 A of lever  19  on a slope  16 A of cam  16  causes the release of click  17  relative to the female wolf toothing  14  prior to the re-engagement thereof in position in the next tooth. 
     This uncoupling, combined with a backward motion, enables the phase train to be uncoupled, and the resulting period where the phase train is uncoupled can be adapted as required. 
     The pitch of the wolf toothing  14  corresponds to a certain elementary duration, according to the number of teeth in the toothing. The length of time until the jump during the next rotation is thus equal to the difference between the duration of the period of wheel  13  on the one hand, and this elementary duration on the other hand. 
     At the time of this jump, the drop of first lever arm  19 A causes lever  19  to pivot; the second arm  19 B thereof is provided with a click  19 C, which cooperates with wolf tooth wheel  24  of the day train  20 . 
     The following description more specifically concerns a first preferred application of this first variant shown in  FIGS. 1 to 6  to the display of the lunar day and phase. 
     Movement  100  directly or indirectly drives, particularly via the cannon pinion, an input wheel  21  and a pinion  11 , which are coaxial in the case of the Figures, but which may equally well have a different arrangement, the arrangement shown being most favourable in terms of space usage. 
     Input wheel  21  has 57 teeth and makes one revolution in 24 hours. Pinion  11  has twelve teeth. 
     For determining the lunar month, a first portion of the train formed by day train  20  has two wheels. 
     Input wheel  21  meshes with an intermediate wheel  22 , which also has 57 teeth, which makes one revolution in twenty-four hours. 
     Intermediate wheel  22  meshes with a lunar day wheel  23  with 59 teeth, which thus makes one revolution in 24 hours 50 minutes and 31.58 seconds. 
     For determining the lunar phase, a second portion of the train formed by phase train  10 , is formed of a very limited number of components. 
     At the input of the train, pinion  11  with twelve teeth meshes with an intermediate wheel  13  called the six hour wheel, which has 72 teeth and which makes one revolution in six hours. 
     This six hour wheel  13  has an inner wolf toothing  14  with 64 teeth. 
     A snail  15  pivots coaxially with six hour wheel  13  and carries a cam  16  including a slope  16 A, and a click  17  with a single tooth, which cooperates with inner toothing  14 . 
     A runner  18 , particularly a ruby, covers the periphery  15 A of snail  15 , and is carried by a lever  19 , pivotably mounted relative to the bottom plate of the movement, and a first arm  19 A of which, carrying runner  18 , is returned towards snail  15  by a spring (not shown in the Figures). 
     When, once per revolution of six hour wheel  13 , runner  18  passes from the high point of snail  16  to the low point, passing over slope  16 A, it releases click  17 , whose tip then takes up the hollow of the next tooth of female toothing  14 . 
     The 0.20000 mm wolf tooth pitch of toothing  14  corresponds to an elementary duration of 5 minutes and 37.5 seconds. The length of time until the jump during the next revolution is thus 6 hours minus this elementary duration, namely 5 hours 54 minutes and 22.5 seconds, i.e. 21262.5 seconds. 
     With an ideal wolf tooth having a pitch of 0.1999999 mm, the elementary duration would be 5 minutes and 37.98 seconds. The length of time until the jump during the next revolution is thus 6 hours minus this elementary duration, namely 5 hours 54 minutes and 22.0 seconds, i.e. 21262.0 seconds. 
     At the time of this jump, the drop of first lever arm  19 A causes the lever to pivot; the second arm  19 B thereof is provided with a click  19 C, which cooperates with a wolf tooth wheel  24  with 140 teeth. 
     This wolf tooth wheel  24  pivots integrally about a pivot axis D 6 , via a jumper spring  25 , of a day arbour  6  carrying a frontal pinion  26  having twelve teeth. This frontal pinion  26  meshes with an arbour wheel  27  with fourteen teeth, integral with a phase arbour  4 , which pivots on a pivot axis D 4  perpendicular to pivot axis D 6 . Consequently, the motion of one tooth of wolf tooth wheel  24  is translated into a rotation of: 360°/140×14/12=3° on phase arbour  4 . 
     A complete revolution of arbour  4 , which thus corresponds to a lunar month, is completed in 360/3=120 times the length of time between two jumps on cam  16 :
 
120×21262.0=2551440 seconds, namely 29.5305833 terrestrial days.
 
     Accuracy of course depends upon the accuracy of the wolf teeth of toothing  14 . 
     This value is a very good approximation of the lunar month. Indeed, the duration of the lunar month is highly variable, from one month to another within one year, and from one year to another, with values frequently varying from one or two hours per month over consecutive months, and up to six hours per month. The usual and arbitrary value of the synodic lunar month of 29.530589 days is a mean value, which is marred by quite a large range of uncertainty, of around 1%. Consequently, the value established according to the invention is excellent. 
     Preferably, the mechanism of the celestial body is mysterious, and thus the first phase arbour  4  is made of sapphire or a material having similar characteristics. This type of sapphire arbour having a diameter of 1 mm, combined with a celestial body sphere  5  made of titanium or an alloy of lower or equal density, having a diameter of 5 mm, can easily resist accelerations of 5000 g. 
     The celestial body sphere  5 , a Moon here in this application, carries different displays  5 A,  5 B, on its two hemispheres. 
     As shown in  FIG. 6 , the first day arbour  6  pivots about its axis D 6 , and takes with it as it pivots arbour  4  carrying celestial body sphere  5 . This arbour  4  thus makes a rotating motion about axis D 6 , during which celestial body sphere  5  pivots about axis D 4 . The trajectory of sphere  5  partially occurs behind a dark screen  8 , made of smoked glass or similar, defining a horizon  9  on pivot axis D 6  of first day arbour  6 . The passing of first mobile component  5  behind the shady portion of screen  8  simulates the position of the celestial body behind the Earth, invisible to the user at the moment concerned, yet allowing the user to see the state of the phase of the celestial body, which explains why screen  8  is dark and not opaque. 
       FIG. 7  illustrates a second variant of the invention, which includes the same day train  20  as in the first variant. Phase train  10  is simplified; female wolf toothing  14  is omitted. The uncoupling means of phase train  10  is the same as in the first variant; however snail  15  pivots integrally with intermediate wheel  13 . 
     Input pinion  11  is still in mesh with the cannon pinion of the movement, or with an intermediate wheel imparting a one hour rotation thereto. Pinion  11  with 12 teeth meshes with an intermediate wheel  12  with 72 teeth. This intermediate wheel  12  is coupled in rotation with a phase wheel  12 A having 64 teeth, which engages with intermediate wheel  13  which has 63 teeth. 
     Snail  15  pivots coaxially with intermediate wheel  13  about axis D 1 ; the periphery  15 A thereof forms a cam  16  similar to the first variant of  FIGS. 1 to 6 . 
     When, once per revolution of intermediate wheel  13 , runner  18  passes from the high point of snail  16  to the low point, passing over beak  16 B and slope  16 A, it causes lever  19  to pivot, and click  19 C to act on wolf tooth wheel  24  of day train  20 . 
     This second variant is more economical to produce than the first variant, because of the smaller number of components and simplified assembly. The combination of toothings results, however, in an error of only 57 seconds per lunar month, which is less than known mechanisms. 
     The invention is well suited to displaying the state of various celestial bodies, and particularly to a combination of such bodies. 
     In a variant, the first day arbour  6  is mounted on a day mobile component  41  which makes a circular or elliptical trajectory about a central axis D 0 . An elliptical trajectory may be obtained by arranging mobile component  41  in a sliding assembly on an arbour, returned by a spring or similar element against an elliptical cam. Day mobile component  41  may also cooperate with an inner circular or elliptical toothing  44  on the trajectory which it is desired to display, as visible in  FIG. 10 , via an external toothing  43  associated therewith and which is advantageously transparent and made of sapphire or similar, and which rolls in this inner toothing  44 . 
     In a complication of the preceding variant, day mobile component  41  carries at least a second sphere  50  which simulates a second celestial body whose angular position can be adjusted by manual adjustment means  45  or by a GMT time zone adjustment train  46  comprised in movement  100 . 
     For example,  FIG. 10  illustrates the relative movement of the Moon and Earth, and the annual orbit of the Earth in a simplified circular form about axis D 0 . 
     In a particular variant, the second sphere  50  of the second celestial body, which is the Earth here, while sphere  5  represents the Moon, is surrounded by a third sphere  51 , one hemisphere of which is transparent, and which, driven by a day/night drive mobile component  47 , makes one revolution whose period is the duration of one day of the second celestial body. Day mobile component  41 , however, pivoted directly or indirectly by train  2 , makes an eccentric revolution whose period is a sub-multiple or multiple of the second celestial body day, or whose period is the duration of one year of the second celestial body. 
     Preferably, mechanism  1  according to the invention display the day and lunar phase of the first celestial body, which is the Moon. 
     In a variant, the second celestial body is the Earth, and mechanism  1  displays, on one hand, the day/night progression in one meridian of the Earth, and on the other hand, the local time of the meridian or the annual position of the Earth on its orbit around the sun. 
     In a particular variant of the invention, sphere  5  symbolising the first celestial body is enclosed in a spherical dome  51  which is transparent over one hemisphere and dark over the other, thus forming a globe with a day portion and a night portion. This globe is pivotally driven. The position of the celestial body in the globe can be adjusted, either by a GMT mechanism as in  FIG. 13 , or manually, by a control stem  45 , on which the intermediate GMT drive wheel is friction mounted.  FIGS. 11 to 13  shows an advantageous type of assembly, in which a mobile component symbolising a celestial body  5  or  50  is pivotably mounted in a cylindrical sleeve  70  having an axis A, which can be driven in rotation about this axis. Sleeve  70  may be in two parts to facilitate assembly. Likewise, the spherical portion representing celestial body  5  or  50  is shown enclosed in a hollow globe made of two parts, wherein two hemispheres may be distinguished into day/night in a plane parallel to axis A or perpendicular to axis A. 
     The invention is equally well suited to representing the Earth, the Moon, or any celestial body with a periodic orbit. 
     In a particular variant representing the Earth, to display to a user from any area in the world a representation of the Earth in which the user&#39;s own country is visible, mechanism  1  includes a means of adjusting Earth sphere  50 , either via a stem  45 , or via a GMT mechanism  46  if the timepiece has one, which has the advantage of leaving the main display unchanged, while displaying the day-night progression on the GMT time zone which is of interest to the user. 
     The invention can be used to produce a cosmographic or astronomical or Earth-Moon watch. 
     For example, in a second GMT time zone, centred on Bolivia in the  FIG. 10  example, a moving Earth-Moon unit travels over the large circle in 12 or 24 hours and provides, via its angular position, the local time: here it is 2 o&#39;clock in the morning in Bolivia, which is still in the darkest sector representing the night. 
     As explained above, within the moving Earth-Moon unit, the Moon rotates about the Earth in one lunar month, while displaying its phases. 
     In a particular variant, the axis of the poles of the Earth remains parallel to the 12 o&#39;clock-6 o&#39;clock axis, as does the axis of the poles of the Moon. 
     In a complicated version, the circular representation of the Earth&#39;s orbit is replaced by an elliptical trajectory. In both cases, the display may advantageously incorporate, in different variants, display signals pertaining to the equinoxes and solstices, and/or signs of the zodiac, and/or the associated lucky symbols for Asian countries. 
     Yet another variant consists in the display of the tidal coefficients according to the GMT time zone. 
     The invention also concerns a movement  100  including a drive means for driving at least one such display mechanism  1 . Advantageously, this movement  100  drives certain functions of the display mechanism, such as a day/night drive mechanism  47  and/or a GMT mechanism  46 , or similar, for driving at least one mobile component  5 ,  50 , representing a celestial body and/or a semi-transparent globe  51  covering a mobile component  5 ,  50  of this type. 
     The invention also concerns an astronomical timepiece, in particular an astronomical watch including at least one movement  100  and/or at least one mechanism  1  of this type.