Gold Medal Software 2/Gold Medal Software Volume 2 (Gold Medal) (1994).iso/misc/dancedem.arj/SAMPLES.SCP

Text File | 1992-03-23 | 22KB | 384 lines

Dance Demo Simulations
objects.rsm
1>>Introduction
Introduction to the Dance v2.5 Demonstration

  Welcome to Dance of the Planets. This special demonstration version offers a
wide variety of simulations illustrating Dance's scope and nature.

* A number of transient sky events- eclipses, solar transits, and occultations.
* Starry skies with constellations, grids, and Skymaps, the new visualization
  mode. The Messier deep sky objects (DSOs) are also included.
* 20 selected asteroids and comets. The complete program has over 6300 -
  virtually all numbered asteroids and recorded comet `apparitions' thru 1991.
* All planets seen from afar, and closeups of Earth and Moon, and the Saturn
  system. Of course in the full program you can zoom in on all the planets.

  The demo won't accept date input, except for the initializing dates used
in the examples- it can be set from 4680 BC to AD 9999 in the full program.
These few limitations leave a lot to see and do - while pleasurably learning
Dance operation. On your first time through, follow the comments and
instructions on each screen, and press [Page Down] when ready for the next.

  [PgDn] now to proceed. At any time you can also press [Home] to see the
demo contents, and from there, jump directly to a particular simulation.

                                              - Thomas Ligon  December 1991

2>>A Starship Perspective
SV>X>01/01.00/1992>C>100>0.5>-10>270>00000000000000000000>
A familiar sky but for the bright central star- the Sun, 3 lightdays distant.
Press ``S' to see orbits- use ``shift-S' to fine adjust these VGA `skylines'. Adjust
monitor brt/contrast for dark space with many stars (some 200 are on screen).
On Control Bar below, note date and ecliptic coordinates of this `Space View'.

3>>Basic Viewing Operations
Space and Earth Viewing Modes.. Basic Viewing Operations

Space View (previous screen) is from outside the solar system. At 1X (next
 screen), the apparent size of constellations and planet orbits are much as
 they would appear out a starship window 270 au from Sun.
Earth View (or Earth's Sky) provides views from a specified Earth `site' from
 which to watch motions/alignments of orbiting bodies against the starry sky.

* Simulation Pace, Zoom magnification, and View direction (latitude,longitude)
  are selected with hot key and changed with cursor keys. Active selections are
  highlighted, simulation is paused. Pressing any other key resumes simulation.
* The screen may be updated for each Zoom and View direction step, or only for
  the final viewing setup by toggling Loc on/off with [ScrollLock].
* View direction may be changed in 1° or 5° steps by toggling Ins on/off, or by
  using cursor keys with [shift] for 1°. (See next screen for Ins and Loc use.)
* SET PACE TO SUIT. Some of the following simulations will be too fast for some
  PCs, too slow for others. Very fast pace settings may reduce accuracy because
  fewer gravitational calculations are performed `per orbit' (steps too large).
* Objects on the screen can be labeled by using [L]abel from the control bar.
* MOUSE OPERATION- point and click selection, roll to change values, and click.
  Use right button as Esc (escape) from menus, return to previous, etc.

  HELP (on Menu or press [F1]) PROVIDES OPERATION GUIDE. Recommended.  [PageDn]

4>>Ins and Loc View effect
SV>X>SC>01/01.00/1992>100>0.5>65>90>00000000000000000000>
(Looking towards Polaris) Ins & Loc affect view changes. For 1° view changes,
put ``Ins' on, or use shift+cursor keys. Toggle ``Insert' key or point/click Ins
bar. Put ``Loc' on for screen redraw for each zoom/view step. Toggle Loc with
``ScrollLock' or point/click Loc bar.              ``/INS bar         /LOC bar'

5>>The Solar System at 1X
SV>X>S>03/26.00/1992>0>1>-17>270>00000000000000000000>
Zooming in on the Solar System (Use keys or mouse point/click/roll for this).
With Loc off, select ``Z'oom, change to 4X with the cursor key, and ``Enter'. ``L'abel
to identify planets. Note clock/calendar with current time. Increase ``P'ace to
see orbital motion- and ``Enter' to resume simulation. Try ``Z'oom with ``Loc' on.

6>>Tracking Earth
SV>earth>S>03/26.00/1992>50>32>-3>144>00000000000000000000>
Tracking Earth- locked at center (``L'abel). At this view angle the different
orbital inclinations of the inner planets are quite evident. Planet motion
is suspended when tracking at low zoom (note Lock-idle below). With Loc off,
zoom to 32kX (32000X) and ``Enter' to resume orbital simulation. ``L'abel Moon.

7>>The Home Planet
EV>earth>0>03/26.00/1992/12>20>0.5>-3>144>0000000000000000000>
The Home Planet. Same view direction as previous screen, but now from special
Apollo viewpoint 250,000 km away (inside the Moon's orbit). ``Z'oom to 2X (max).
Select Planet ``G'rid from menu, ``shift-S' to adjust VGA. Press any key to erase
grid. ``M'ore Options on menu provides 2nd menu with cloud on/off toggle.

8>>From the Earth's Sky
EV>X>S>01/01.00/1990>1000>0.5>-26>18h00>00000000000000000000>
In Earth's Sky- view towards Sagittarius from Earth. Here is a grand planet
rendezvous in the morning sky, early Feb 1990. Identify with ``L'abel. Note the
`View' declination, right ascension of center cross. Change ``P'ace to suit and
watch into February. The Sun's rays correspond to 1 hr from sunset/sunrise.

9>>Constellations and Grids
EV>0>1>11/20.00/1992>1000>0.5>11>04h20>00000000000000000000>
Constellations & Grids. Press ``F' for Find, type in Leo. Select ``C'onstelDraw on
menu for lines. Adjust VGA with ``shift-S'. To see declination/right ascension
grid, select Celest ``G'rid on menu. These `skylines', constellation lines and
coordinate grids, will remain in the sky until toggled off on menu.

10>>Ancient Guidestar
EV>X>CG>03/21.00/-2850>10>min>75>00h00>00000000000000000000>
A familiar north sky, but note the date. Press ``S' for skylines- dim for subtle
effect. The Earth's axial direction precesses about the ecliptic north, and
at this time alpha Draco was the polar star. At 1X, you can ``L'abel this
modest star.

11>>A Dance Skymap
EV>X>SG>C>80k>skymap>-10>12h00>11111111111111110000>
Looking toward Virgo. With a Skymap, over 75% of the entire celestial sphere
can be viewed. ``L'abel to identify the planets, comets and asteroids included
with the demo. To see a full-sky map at your location and time, set ``P'ace to
`true', re-enter the date and your Site ``C'oords (2nd menu), and ``F'ind `zenith'.

12>>Christmas Stars
EV>X>0>06/17.18/-1>50>0.5>23.5>07h08>00000000000000000000>
A number of celestial events around year 0 are Christmas star candidates.
Here is a close conjunction of Jupiter and Venus in the western sky (``L'abel),
June of 2 bc (Year-1=2 bc). Set site Coords to 31.5, 35.1 for Jerusalem and
re-enter date. ``Z'oom down to min and ``F'ind `west hor' at about 20 hours (8 pm).

13>>DSOs and Messier Objects
EV>X>1>11/20.00/1992>1000>0.5>12>4h40>00000000000000000000>
The Messier deep sky objects (DSOs) include many star clusters and galaxies.
Select ``D'eepSky Objs from menu, press ``M' or ``Enter' to select. Press ``Esc' to
exit menus. ``F'ind `M31' for the Andromeda galaxy. DSOs are dim- adjust monitor.
`Label stars and DSOs with Skylns on'. DSOs show until toggled off on menu.

14>>Fixed Moon with Occultation
EV>moon>0>08/13.16/1990>50>2>40>-105>00000000000000000000>
When viewing the sky, ``F'ind `fix moon' both locates and fixes the Moon at the
center (already done here). Zoom to 8X to watch this Pleiades occultation.
Adjust the earthshine with ``S'kylns. When fixed on Moon, Sun or planet, ``Esc'
releases tracking. Site Coords on 2nd menu shows this to be a Colorado site.

15>>Lunar Eclipse
EV>moon>0>02/10.02/1990>50>8>-30>150>00000000000000000000>
The Moon passing through the Earth's shadow- view from Australia. The partial
shadow of the Earth, the penumbra, appears first at about 2:30 local time. In
this lunar eclipse simulation, a rusty sunset color leads into the deep shade
of the umbra. Due to atmospheric refraction, the Moon is never entirely dark.

16>>The 1991 Solar Eclipse
EV>sun>0>07/11.10/1991>50>8>23.6>-110.8>00000000000000000000>
The Big One. 1991 solar eclipse as seen from La Paz, Baja California. Change
Pace to suit. Just before totality (around 11:45), slow to 1 or even `true'.
Note corona and stars. Use Site Coords on ``M'ore Options menu to check/change
location. If you change sites, note that the time of maximum eclipse changes.

17>>Venus Solar Transit
EV>sun>0>06/08.06/2004>50>16>30>31.2>00000000000000000000>
A Venus Solar transit viewed from Cairo. These are rare events- none occurred
in the 20th century; two will in the 21st. The next one is simulated here,
and begins at about 7:25 local time. Use Label to locate Venus before and
after the transit.

18>>Virtues of Just Watching
EV>sun>S>03/15.00/1993>10k>0.5>40>-105>111111000>00000000000000000000>
Favorable apparitions (appearances) can be found in a number of ways with
Dance. One way to find these maximum solar extensions is illustrated here.
The Sun is fixed- ``L'abel to identify Mercury. Note morning and evening
apparitions in April and June.

19>>Viewing Planets Up Close
Viewing Planets Up Close

  Zoom and view the solar system from any angle, but the Sun will remain
central in `Space View' unless the Dance telescope is tracking a planet. To
view a planet up close, lock on by

 1) using the Planets menu (on main menu) or
 2) select Target&Lock from main menu, place box over planet and press [Enter].

  The name of the tracked planet appears in the control bar. From the distant
space viewpoint you can zoom to 32kX magnification. Since from 270 a.u. all the
planets are approximately the same distance away, they will appear scaled to
one another. From Earth you can zoom to 512X. The apparent size of the planets
will be as they appear from Earth at that time.

  In the next screen Saturn is already locked in- shown with it are all the
asteroids & comets included with the demo. (In such a Space View the planet
or Sun can be moved anywhere on screen using Move Center- 2nd menu.) So many
orbits take some time to calculate and draw, so there may be some pause.

20>>Tracking on to Saturn
SV>Saturn>S>11/16.00/1989>200>16>-6>300>111111111>11111111111111110000>
Saturn locked on for close viewing (simulation idle at low zoom). Orbits of 16
asteroids/comets, as well Saturn's outer-most satellite, Phoebe, are visible.
Move Saturn toward upper right using ``M'ove Center (2nd menu). With blue
cursor at desired spot, ``Enter' to move center. Adjust VGA Skylns. ``L'abel.

21>>Saturn's Satellites
SV>Saturn>S>07/01.00/1992>200>1k>0>293>S111111111111111111>
Saturn's major satellites. At 1000X Phoebe's orbit is partly off screen. You
can ``I'nvert for north to be down (note north-pointing arrowhead). Label to
identify the satellites. Turn View ``Loc' on with ``ScrollLock' and then ``Z'oom up
in 2X steps. Press any other key to resume simulation.

22>>Saturn Up Close
SV>Saturn>0>11/16.10/1989>200>32k>0>343>S111111111111111111>
Saturn at full power- Titan coming up from below. Toggle orbit skylines on/
off. ``L'abel satellites. Change View longitude to better see the rings- they
darken as viewing moves towards the back. At this time the rings are near max
tilt to the Sun, so Saturn casts a short shadow on the ring-satellite plane.

23>>Saturn-star Occultation
EV>sat>0>07/03.00/1989>50>-512>59.3>18.3>00000000000000000000>
An Earth View of Saturn simulating the occultation of 28 Sgr, a 5.4 magnitude
star, as seen from Stockholm. This is the brightest star occulted by Saturn
known. From some locations in Europe, 28 Sgr slipped behind Titan as well!


24>>Comets Revealed
SV>X>S>06/15.00/1989>100>0.5>-13>90>00000000000101110000>
A small comet sampling as seen from afar. Note the two parabolic orbits. Such
comets, seen only once, may approach from any direction. Orbits of periodic
comets Halley and Encke are also present. Zoom to 4X and ``L'abel. Zoom to 16X,
``S'kylns off, set a high ``P'ace and watch the tails of the parabolic comets.

25>>Halley Perihelion
SV>X>S>10/15.00/1985>2k>32>-10>330>111110000>00000000000100000000>
Comet Halley approaching perihelion. Adjust ``P'ace and ``S'kylns to better see the
developing tail. Select Sub ``E'cliptic (2nd menu) to see what portion of its
orbit is below the ecliptic. Never close to any planet, Comet Halley's orbit is
is relatively stable. View toward 90°S (from overhead) and re-enter date.

26>>Halley Apparition
EV>X>0>12/25.00/1985>20k>0.5>-23>21h00>111110000>00000000000100000000>
Halley Revisited - An Earth view. The 1986 apparition was poor; you can see
why. Adjust Pace and watch while the comet passes through perihelion, Feb. 8,
1986 (your PC will bleep). Note the apparent speed increase as the comet
angles down for its southerly ecliptic plunge. Skylns off to better see tail.

27>>Celestial Tracks
EV>X>SG>10/01.00/1985>80k>skymap>-30>20h40>111110000>00000000000100000000>
A long view of Comet Halley- it appears from the left as it passes north of
the ecliptic, reaching perihelion on 9 Feb 1986. Apparent motion accelerates
as it passes nearest Earth. Due to our moving platform (Earth), the comet is
now making epicycles in the sky as it makes its long journey out to aphelion.

28>>Orbital Simulation
The Simulation Nature of Dance

  Dance is an orbital simulator. This means that the program is constantly
calculating the gravitational effects of the various bodies on one another and
moving them accordingly. In the program `real' distances, masses and velocities
are operating according to Newtonian gravitation in three dimensional space,
and the results are scaled and transformed to the screen. Dance is a detailed
working model of the solar system that can not only show views and events that
are calculable, but also simulate perturbations and other complex multiple-
bodied orbital interactions that are generally not. Being able to predict orbit
changing encounters of the past and future is an exciting and unique aspect of
Dance. With the full database of asteroids and comets you can discover events
and causes that few if anyone else knows about.

  The next simulation shows an interesting future event with comet Kojima.
Discovered in 1970, Kojima has a period of nearly 8 years, and has been very
regular for three apparitions. During the encounter, simulation will slow as
Dance performs more calculations to maintain accuracy. The strongest change to
the comet's orbit will be an increase of inclination to the ecliptic plane.

29>>Comet Futures
SV>X>S>09/01.00/1995>40k>8>-35>90>111111000>00000000000010000000>
A Strong Perturbation. Kojima's orbit, like most periodic comets, is chaotic.
Simulation reveals a strong orbit-changing Jupiter encounter during 1996-1997.
Result: an earlier, brighter apparition. Encounter distance (in planet radii)
will appear upper left. Jupiter's outermost satellites are out some 320 radii.

30>>Bright Asteroids
SV>X>S>09/20.00/1990>5k>8>-90>90>111110000>11111000000000000000>
Bright asteroids (dim ``S'kylns). Ceres is the largest; over 900 km diameter.
Only Vesta is ever brighter than mag 6. When viewing 90° N/S, a line marking
the vernal equinox direction (0° longitude) is shown. Viewing 5°S, note the
orbit of Pallas. Object Status (``A'ccess menu) gives object observation data.

31>>Some Asteroid Extremes
SP>X>S>01/09.00/1991>20k>8>-13>120>111111100>00000000110000000000>
At the time of their discovery, asteroids Hidalgo and Icarus moved farthest
and closest to the Sun. Label to identify. Zoom to 32X, pace 40k-80k, to see
Icarus zipping through perihelion. Turn View toward 90°S. Move the Sun upward
get all of Icarus's orbit on screen using ``M'ove Center (``M'ore Options menu).

32>>Asteroids in the Sky
EV>X>S>03/01.00/1989>20k>0.5>-33>18h00>111111110>00111000000000000000>
Asteroids In A Starry Sky- looking towards Sagittarius from Earth in 1989.
The motion and paths of several bodies are seen. Watch the epicycles through
1989. Planet coordinates are on the ``A'ccess screen- there select ``O'bject Status
for asteroid position/magn. In June-July Vesta was at maximum brightness.

33>>Asteroid 1989FC
SV>X>S>02/01.00/1989>2000>64>-20>45>111110000>00000000001000000000>
Our brush with asteroid 1989FC was closest known at the time, 400,000 miles
in March of 1989. Though small, 1989FC would have caused havoc had it struck.
Dim and fast moving, Earth-crossers are hard to find. You can check out many
in Dance. Slow pace in mid-march noting date and min distance (Earth radii).

34>>Orbital Resonances
Orbital Resonances

  Asteroids with periods that are a simple ratio to Jupiter's are regularly
perturbed by it. Such resonances have depopulated the Kirkwood gaps, that is,
asteroids with periods near these resonant values are not found. But resonances
with ratios near one can provide an island of orbital stability. These `island'
resonances provide one classification for Asteroids. Trojan asteroids, with a
ratio of 1:1, essentially share Jupiter's orbit. In this `Lagrangian resonance'
the asteroid is nominally 60° ahead or behind, never getting too close. There
are over 100 Trojans known. Hildas are another large group with 3:2 resonances.

  Resonances are also found among the satellites of the Jovian planets. The
Galilean satellites have period ratios very nearly 1:2:3:4 (check the Access
Satellites screen for Jupiter when planet tracking). Like the hands of a clock,
they have regular `meeting places'. The Saturnian system is full of resonances,
including co-orbital satellites with Lagrangian resonances.

  When you have the Saturn system on the screen in some of the following simul-
ations, press [A]ccess and select Satellites from the menu. Note the periods
for co-orbital satellites and other resonances. Esc to return to the simulator.

35>>Tuned Asteroids
SV>X>S>08/01.00/1988>80k>8>-90>270>000010000>00000111000000000000>
Asteroid Resonances- Living with Jupiter. (Dim Skylns- inner planets are off
for speed.) Some stable resonances: Hilda, the first 3:2 resonance found;
Achilles, the first 1:1 Trojan asteroid. Thule, the only known 4:3, is quite
perturbed every 3 Jovian (36 Earth) years. Watch through 2018. Pace to suit.

36>>Tuned Satellites
SV>Saturn>S>07/01.00/1990>2k>4k>-70>35>S000000000000001100>
Satellite Resonances (Dim Skylns and Label to find and watch Hyperion.) With
a 3:4 resonance, Hyperion avoids strong perturbation from Titan by being
near maximum separation whenever they pass. The influence still causes pre-
cession of Hyperion's orbit. Inner satellites are off for speed.

37>>Doing Orbital Experiments
Doing Orbital Experiments

  Orbital elements of real or hypothetical objects orbiting the Sun can be
placed in a text file and loaded into Dance. On the next screen you will see
four hypothetical objects with the same period but with very different eccen-
tricities. Such examples can vividly illustrate basic principles of orbital
mechanics- in this case, that the orbital period about a single massive body
depends only on the semi-major axis of the orbit. An introduction to the
basic theory, along with simulation examples, can be found in the Dance manual.

  Examples of other enlightening experiments: 1) using hypothetical objects to
see whether regularly spaced, nearly circular orbits between the Jovian planets
are stable. 2) How, starting with a `primordial' distribution of asteroids
(near-circular and regularly spaced), the Kirkwood gaps arise. Such experiments
involve a lot of objects and time. A reasonably fast PC with coprocessor is
recommended. Very long simulations can be saved in Resume files and run over
several nights.

38>>Hypothetic Asteroids
SV>X>S>->20k>8>-90>90>000000000>00000000000000001111>
Four hypothetical objects with the same period. Note the semimajor axes are
equal- from basic orbital theory, the period is determined solely by the semi-
major axis and mass. The four start together (note perihelion `blip' sounds).
Pace to 240k and note any accumulative simulation error by spread in blips.

39>>Ordering and Updates Info
Ordering and Updates                                  December 16, 1991

DANCE OF THE PLANETS, version 2.5, is available for $195 plus shipping and
handling. Future versions may be subject to price increases. Please order from:

     A.R.C. Software
     P.O. Box 1955
     Loveland, CO 80539

For information or ordering call 1-800-SKY-1642, or fax to 1-303-667-1105. MC/
Visa accepted as well as authorized purchase orders. Postage paid on domestic
orders paying by check or money order. Foreign orders must be prepaid (charge
cards accepted) and include shipping and handling- $15 for Canada and Mexico,
$25 for Europe plus other western hemisphere, and $35 for eastern hemisphere.
Thank you for your support and interest.

40>>A Southern Skymap
EV>X>SGC>09/01.00/1992>80k>skymap>-70>12h40>111111111>00000000000000000000>
The end of the demo and a nice view of the southern sky. Adjust ``S'kylns for
subtle effect. From here, press ``Home' for contents, from which you can go to
any demo page. Or press ``Esc' to leave the script mode- ``R'edraw to erase this,
and then explore the Dance sky and solar system on your own. Use ``F1 for Help'.