Horizontal Panel Motions

Most motions are controlled by a speed-control knob. Above each knob is a lighted indicator label. To the left of the lighted label is a Reverse Direction switch; to the right of the label is a Forward Direction switch. Note the following points about the operation of these knobs and direction switches:

After selecting either the Forward or Reverse switch associated with a particular motion, turn the motion's speed-control knob clockwise from the OFF position. The speed of motion increases as the knob is rotated clockwise (to the right). Rotating the knob counterclockwise (to the left) slows the motion.
To stop a motion, turn the knob to 0 or to the OFF position.
Make sure that the knob is in the OFF position before changing the direction of motion by selecting either the Forward or Reverse switches. As a safety feature to avoid gear damage, the projector will not change direction without the knob first being turned to the off position.
The final motion should always be in the forward direction, in order to minimize gap space between gears. When bringing the projector into some alignment using the reverse direction, pass slightly by the desired alignment and then come slowly back using forward motion.

Location
(Horizontal Panel) Label Objective Operation or
Caution

Top row
far left Turn-table Rotates the entire projector, changing the projected cardinal directions.
The turntable moves a maximum of about one and one quarter turns in either direction from the Home direction.

Top row, above TT knob Turn-table Reset Returns the projector to its preset home position after being moved to another direction.
1. Select either Forward or Reverse of the Latitude Change switch, turn the knob to OFF.

2. Next push the Turntable Reset button. The projector will automatically return to the preset Home position and stop.

CAUTION : If the speed-control knob is not in the OFF position when the Turntable Reset button is pressed, the machine will not stop automatically but will instead continue rotating.

CAUTION: If the turntable has been moved more than one complete turn away from its Home position, the Reset button will not return it to true Home, but only to a position aligned with Home even if it is precisely one turn away from Home.

Top row
2nd from left Diurnal Motion Reproduces the diurnal motion (daily rotation) of the Earth
Forward direction is defined as the ordinary westward motion that the sun and stars appear to follow daily across the sky.

Vertical Panel
middle area beneath Script Holder Recess
(CC on diagram) Diurnal / Annual Coupling Clutch Couples the motions of the Sun, Moon and Planets with diurnal motion and so that they move with synchronized speeds. Or, when decoupled, allows for demonstration of diurnal motion of the stars independently of annual motion.
1. When the switch is ON (engaging the diurnal / annual coupling device), the Diurnal Motion switch and knob (Horizontal Panel, top row, 2nd from right) activate this feature. In this mode, as one day turns one rotation with diurnal motion, the position of the Sun, Moon and five planets also move forward by a day.

2. When the switch is OFF (disengaging the diurnal /annual coupling device), the Diurnal Motion switch and knob deactivate this feature. In this mode, even if diurnal motion turns through one day, the Sun, Moon and five planets will not move, but rather, will remain fixed in their original positions.

Top row
3rd from left Annual Motion Depicts the eastward motion of the Sun, Moon and five planets against the background of fixed stars.
Forward direction is defined as the direction of the Sun's annual motion, or the slow eastward "falling behind" of the Sun against the background of the fixed stars.

Top row
3rd from right Latitude Motion Rotates the latitude axis of the GS-T; projects the starry sky as seen from any latitude on the surface of the Earth.
1. Forward direction is defined as the north polar point moving along the meridian from north to 90° (zenith) to south.

2. Note that "latitude" pertains to the position of the earth-bound observer, not to the stars. This motion, swinging the celestial equator higher or lower above the horizon, allows stars of different declination to be viewed. (The axis of motion for celestial latitudes would swing along the ecliptic, not the celestial equator.)

Top row
2nd from right Precession Motion Depicts the shifting intersection of the celestial equator and the ecliptic against the background of fixed stars, throughout its
26,000 year cycle.
1. Forward direction is defined as movement from the past or the present towards the future. Reverse is defined as movement from the present or future into the past.

2. In order to see precessional motion, illuminate the Precession Circle (Horizontal Panel, middle row, 3rd from left). The "+" direction on the grid is the future, the "-" direction is the past.

Warning: Do not run diurnal motion when the Precession is set more than two or three thousands of years away from the present. Precession changes the orientation of bright star projectors on the machine, which may not clear the star projector supports at extreme precessional positions.

Top row
far right Altitude Allows a 90° horizon-to-zenith coordinate grid to be moved to the desired azimuth. This altitude arc merges with the meridian when due north or south, but can be swung around 360° to any azimuth.
1. Turn the Altitude coordinate lamp on with the central button (between the R and F switches).

2. Set the direction of motion with the Reverse or Forward switch.

3. Finally, adjust the speed with the speed- control knob.

NOTE: If motion in a reverse direction is necessary, always overshoot in the reverse direction and come back with forward motion. Because of the way the gear teeth come into contact, the last motion on any axis should be in the forward direction. This will provide finer and more responsive control when motion is resumed, and increase the longevity of the projector.

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Welcome to the Planetarium web site provided by the OBU Planetarium. These pages have been written by the Planetarium Director, Kerry Magruder; the Unified Studies Natural Science Coordinator, Mike Keas; other OBU faculty; and the students who work in the planetarium.

These web pages may be printed, copied, and distributed for educational use by any non-profit educational group so long as they are not edited or altered in any way, nor distributed for profit, nor repackaged or incorporated into any other medium or product, and so long as full credit is given to the OBU Planetarium.

This page and many others from the same web site may be accessed from the OBU Planetarium Home Page.

Our web pages are never finished, but always under construction! The formatting of our web pages may be unintelligible if you are not using Netscape 2.0+. If you find a link that does not work, please tell us which link does not work--and which page you are on. Contact us by Email with general inquiries or suggestions. Thank you.

Page made with HyperNote and Claris Home Page

Kerry Magruder, Planetarium Director, Home page or Email

Mike Keas, Unified Studies Natural Sciences Coordinator, Home page

Primary Email: mike_keas@mail.okbu.edu
Secondary Email: Newtonkeas@aol.com

Related Web Pages:

Constellations Index Page
The OBU Planetarium's Basic Celestial Phenomena Home Page
OBU Planetarium Home Page
OBU Unified Studies Natural Science Home Page
Home Page of the OBU Division of Natural Sciences and Mathematics
General OBU Home Page

Location (Horizontal Panel)	Label	Objective	Operation or Caution
Top row far left	Turn-table	Rotates the entire projector, changing the projected cardinal directions.	The turntable moves a maximum of about one and one quarter turns in either direction from the Home direction.
Top row, above TT knob	Turn-table Reset	Returns the projector to its preset home position after being moved to another direction.	1. Select either Forward or Reverse of the Latitude Change switch, turn the knob to OFF. 2. Next push the Turntable Reset button. The projector will automatically return to the preset Home position and stop. CAUTION : If the speed-control knob is not in the OFF position when the Turntable Reset button is pressed, the machine will not stop automatically but will instead continue rotating. CAUTION: If the turntable has been moved more than one complete turn away from its Home position, the Reset button will not return it to true Home, but only to a position aligned with Home even if it is precisely one turn away from Home.
Top row 2nd from left	Diurnal Motion	Reproduces the diurnal motion (daily rotation) of the Earth	Forward direction is defined as the ordinary westward motion that the sun and stars appear to follow daily across the sky.
Vertical Panel middle area beneath Script Holder Recess (CC on diagram)	Diurnal / Annual Coupling Clutch	Couples the motions of the Sun, Moon and Planets with diurnal motion and so that they move with synchronized speeds. Or, when decoupled, allows for demonstration of diurnal motion of the stars independently of annual motion.	1. When the switch is ON (engaging the diurnal / annual coupling device), the Diurnal Motion switch and knob (Horizontal Panel, top row, 2nd from right) activate this feature. In this mode, as one day turns one rotation with diurnal motion, the position of the Sun, Moon and five planets also move forward by a day. 2. When the switch is OFF (disengaging the diurnal /annual coupling device), the Diurnal Motion switch and knob deactivate this feature. In this mode, even if diurnal motion turns through one day, the Sun, Moon and five planets will not move, but rather, will remain fixed in their original positions.
Top row 3rd from left	Annual Motion	Depicts the eastward motion of the Sun, Moon and five planets against the background of fixed stars.	Forward direction is defined as the direction of the Sun's annual motion, or the slow eastward "falling behind" of the Sun against the background of the fixed stars.
Top row 3rd from right	Latitude Motion	Rotates the latitude axis of the GS-T; projects the starry sky as seen from any latitude on the surface of the Earth.	1. Forward direction is defined as the north polar point moving along the meridian from north to 90° (zenith) to south. 2. Note that "latitude" pertains to the position of the earth-bound observer, not to the stars. This motion, swinging the celestial equator higher or lower above the horizon, allows stars of different declination to be viewed. (The axis of motion for celestial latitudes would swing along the ecliptic, not the celestial equator.)
Top row 2nd from right	Precession Motion	Depicts the shifting intersection of the celestial equator and the ecliptic against the background of fixed stars, throughout its 26,000 year cycle.	1. Forward direction is defined as movement from the past or the present towards the future. Reverse is defined as movement from the present or future into the past. 2. In order to see precessional motion, illuminate the Precession Circle (Horizontal Panel, middle row, 3rd from left). The "+" direction on the grid is the future, the "-" direction is the past. Warning: Do not run diurnal motion when the Precession is set more than two or three thousands of years away from the present. Precession changes the orientation of bright star projectors on the machine, which may not clear the star projector supports at extreme precessional positions.
Top row far right	Altitude	Allows a 90° horizon-to-zenith coordinate grid to be moved to the desired azimuth. This altitude arc merges with the meridian when due north or south, but can be swung around 360° to any azimuth.	1. Turn the Altitude coordinate lamp on with the central button (between the R and F switches). 2. Set the direction of motion with the Reverse or Forward switch. 3. Finally, adjust the speed with the speed- control knob.