FR2679052A1 - Mini-planetarium clock - Google Patents

Abstract

Mini-planetarium clock reproducing the apparent motions of the sun, moon and Earth over a time scale. The invention relates to a device which represents the schematic view from a viewpoint situated a few tens of thousands of kilometres above one of the Earth's poles. It consists of a dial (1) representing a map of the sky, a representation of the sun (2), a representation of the moon (3), a representation of the Earth (4), a clockwork mechanism (10) with three coaxial spindles (5, 6, 7) and the supports for the representations of the heavenly bodies (8, 9). The device according to the invention is particularly intended as a teaching aid in astronomy, whilst also serving as a conventional clock.

Description

 The present invention relates to a mini planetarium clock which reproduces on an hourly scale the apparent movements of the sun, the moon and the earth.

 The purpose of this invention is to facilitate the understanding of astronomical concepts such as: apparent movements of the sky, apparent movements of the sun, solar day, sidereal day, phases of the moon, sidereal revolution and synodic revolution of the moon, ecliptic, eclipses, etc.

And this in a single device, which also gives the exact time at all times.

 The device makes it possible to replace, and / or serve as a complement, to flow diagrams used to explain such astronomical concepts, while serving as a conventional clock.

The term "clock" is used here to indicate a device for indicating the time, the principle of the invention being applicable to wristwatches, foot clocks, wall clocks, pendulums or the like
The device according to the invention represents a schematic vision of a point of view located a few tens of thousands of kilometers above one of the poles of the earth and moving in space synchronously with it.

 Figures 1 (front view) and 2 (side view) help to understand the device.

The device according to the invention consists essentially of: a dial (1) representing a sky map, a representation of the sun (2), a representation of the moon (3), a representation of the earth (4), a mechanism clockwork (10) with three co-axial axes (5,6,7) and the supports (8,9) of the representations of the stars
The dial (1) represents a sky map, which in this case, and by way of nonlimiting example, is flat and circular, but for aesthetic or functional reasons one can adopt any other shape (oval, square, concave, convex, etc.), which may or may not include hourly markers (12) or others.

 The choice of the sky map will be established according to the chosen model; in our example, it represents the whole of the northern celestial hemisphere and part of the southern celestial hemisphere, in such a way that the line of the ecliptic (11) fits entirely into the dial (1); that is to say that our example corresponds to a schematic vision from above the south pole.

 The north celestial pole coincides in our example with the center of the dial (1), it is at this point that the motor co-axial axes (5,6,7) are placed perpendicular to the dial.

 One can also use the central point of the ecliptic (11) as the center of the dial (l) and location of the motor axes (5,6,7) in such a way that the course of the representation of the sun (2) coincides exactly with the ecliptic (11), in this case, account will be taken of the fact that the representation of the earth (4) will remain displaced from its celestial axis by 23 27 '.

This remark is valid for the two celestial hemispheres.

 In the example, the representations of the stars are made in volume, although other representations are possible (drawn discs, photographs or others); similarly, the proportions are given only by way of example.

 The representations of the sun (2) and the moon (3), in the example, are integral with their respective axes (5,6) by means of the rods (8,9) although other supports are possible (for example transparent discs).

 The representation of the sun (2) is integral with the time axis (5) and will be the furthest from the center, and its distance from the center will be determined so that its course is as close as possible to the line of the ecliptic (ll) this representation of the sun (2) can, depending on the model, be illuminated from the inside using any means (LED, optical fiber, bulb, etc.).

 The representation of the moon (3), integral with the minute axis (6) is closer to the center than the representation of the sun (2).

The representation of the earth (4) is integral with the central axis (7)
The drive of the assembly is given for a clock mechanism (10) whose axis (5) rotates in 12 hours,
the axis (6) rotates in 1 hour, and the central axis (7) rotates in
2 minutes.

The principle of the timescale is as follows:
- The representation of the sun (2) makes a complete tour of the ca
dran (1) - representing the sky - in 12 hours, which is equivalent
to a year in the device.

- The representation of the moon (3) makes a complete tour of the
dial (1) in 1 hour and represents in the device the re
sidereal evolution of the moon (which is in reality 27
days, 7 hours, 43 minutes on average).

Which gives us a report of 12 sidereal revolutions
of the representation of the moon (3) for a revolution of the
representation of the sun (2) - ie for year of dis
positive -. Which pretty much coincides with the actual report
(approximately 13.35 sidereal revolutions of the moon per year).

- The representation of the earth (4) making a complete turn
on itself in 2 minutes, represents the sidereal days of the
device, which gives us a report of 360 revolutions (days
siderals of the device) in 12 hours (year of the device)
for an actual ratio of approximately 366 1/4 sidereal days and
365 1/4 solar days per year. The solar day of disposi
tif is a few fractions of a second higher than its
sidereal day.

If, as in the example, we place the hourly haunt
from 12 a.m. - 12 p.m. (12) in the celestial meridian corresponding to the
position of the sun on December 31 at 0 h UT -18 h 38 min. ace
right cension - in the constellation Sagittarius we can
assimilate each hour to a month of the year, example: 0 h to
I h corresponds to the month of January, 1 h to 2 h the month of fé
vrier, etc. In this way, we can know at a glance,
approximately the position of the sun on a given date
(for example at solstices and equinoxes).

- Note that the direction of rotation of each star represents
felt (2,3,4) should be the same as in a suitable clock
tional. This is valid for our representative example
a schematic view from above the south pole. For a disposi
tif showing a schematic view from above the north pole, in
plus changes to the celestial map, which would show what
all the southern celestial hemisphere in its entirety, and one per
Tie of the northern celestial emisphere, the representations of the as mentioned (2,3,4) must turn in the opposite direction to the hands of a conventional clock.

 We can consider in some cases the use of a conventional clockwork mechanism while taking into account that in this case the representation of the earth (4) will rotate 2 times faster on our time scale, which for educational purposes is not very annoying.

 The device according to the invention is particularly intended as an educational aid in astronomy, while remaining a device used to indicate the time.

Claims (7)

 1) Mini planetarium clock reproducing on an hourly scale the apparent movements of the sun, the moon and the earth. It is characterized by a device which corresponds to a schematic vision from a point of view located a few tens of thousands of kilometers above one of the poles of the earth; this device is essentially composed by: A dial (1) representing a sky map, a representation of the sun (2) making a complete rotation of the dial (1) in 12 hours, a representation of the moon (3) making a rotation of the dial (1) in 1 hour, a representation of the earth (4) turning on itself in 2 minutes, a clockwork mechanism (10) with three co-axial axes (5,6,7), and the supports of the representations of the stars (8,9).  2) Clock according to claim 1 characterized in that its principle is applicable to wristwatches, wall clocks, foot clocks or pendulums.  3) Clock according to claims 1 and 2 characterized in that the dial (1) represents a sky map, comprising a celestial hemisphere and part of the other hemisphere, so that the line of the ecliptic fits into it all in the dial (1), the sky map is centered on its celestial pole or on the center of the ecliptic (11), center or are placed the motor axes (5,6,7).  4) Clock according to claims 1 and 2 characterized in that the representation of the sun (2) is the furthest from the center and its course is very close to or coincides with the line of the ecliptic (12), this representation of the sun (2 ) can be lit from the inside using any means (LED, fiber optic or bulb).  5) Clock according to claims 1 and 2 characterized in that the supports (8,9) can be rigid rods or transparent discs.  6) Clock according to claims 1 and 2 characterized in that the axis (5) rotates in 12 hours, the axis (6) rotates in 1 hour, and the central axis (7) rotates in 2 minutes.  .7) Clock according to claims 1 and 2 characterized in that the clockwork mechanism is a conventional clockwork mechanism.