Solar System

[davey110]

This program is an "Orrery". Look it up.

This model of the Solar System shows all the planets (including the Moon and Pluto) orbiting around the Sun. You can adjust the display speed and the zoom to show the inner and outer planets moving at their correct relative speeds.

You can have the program stop at a particular date by choosing "Enter a starting date", or you can toggle Stop/Go by tapping a button. One check for accuracy is to enter a stop date for a future eclipse or conjunction etc, then note the position of the moon or planet on the display. (Sorry; 31 Jan 2025 is the earliest date it will accept).

Although this program shows the planets positions reasonably accurately on any particular date, it is not designed to be precise; the orbit diameters are to scale, but are circular, not elliptical, so the orbital speeds are constant, not varying at perihelion and aphelion. This will give a slight inaccuracy in their positions, which, at the scale drawn, will probably not be noticeable to the naked eye. In particular, Pluto's orbit is represented by a circle with its centre offset from the Sun so that it crosses Neptune's orbit in a realistic looking manner, though not perfectly accurate.

The Moons distance from earth is greatly exaggerated to make it distinguishable from Earth.
The planets sizes are not to scale, other than the inner planets being smaller than the outer ones. The sizes do not change with the scale.
Day#1 is Jan 31/2025, because that was the best date I could find starting data for.
Note: Celestial Longitude is measured CCW; Smart BASIC measures angles CW.

Undoubtedly, there will be routines that could be simpler than what I have done.

Code: Select all

 
 /*
This is RAW DATA from an astronomy handbook; only used for reference when writing the program:
   	Dist(millions-km)   Revolution(days) (All are Siderial times)
Mercury             57.9          88.0
Venus              108.1         224.7
Earth               149.5         365.258
Mars                227.8         687.0
Jupiter            778          4332 days = 11.86 years (program works in days)
Saturn            1427         10760        = 29.46
Uranus           2869         30685        = 84.01
Neptune         4497         60195        = 164.8
Pluto              5900         90475        = 247.7   
Moon              0.3          27.321661 
Pluto: Eccentricity = 0.25    Longitude of Perihelion = 224º
Pluto's eccentricity is simulated by an offset circle.
Earth Perhelion = 102º 
*/     
 
 '  =============== PROGRAM BEGINS HERE =============================
'b'
OPTION BASE 1 
OPTION ANGLE DEGREES   
SET BUTTONS CUSTOM

DIM pname$(10), dist(10), pper(10), ppos(10), mon$(13), days(13) 'dacc(13) 
  ' pperiod (days), dist (mill km) init pos of planets is 31 Jan/25.

'r'
'Calendar for dates:
DATA "Jan",31,"Feb",28,"Mar",31,"Apr",30,"May",31,"Jun",30,"Jul",31,"Aug",31
DATA "Sep",30, "Oct",31,"Nov",30, "Dec",31

FOR i=1 TO 12
   READ mon$(i), days(i)
NEXT i

'------------------------------------
'Table of planet data: 
'  Name   Dist(mill km) RevPer'd(d)  Start Long't'd (is initial pang() on Jan 31/2025)
DATA "Mercury", 57.9,     88.0,         -289,      "Venus", 108.1, 224.7, -100, "Earth", 149.5, 365.258, -131
DATA "Mars", 227.8, 687.0, -123, "Jupiter", 778, 4331.98, -81, "Saturn", 1427, 10760, -350
DATA "Uranus", 2869, 30685, -56, "Neptune", 4497, 60194, 1, "Pluto",5900,90475, 60, "Moon", 7, 27.321661, 25 'moon dist is exaggerated to display outside earth.
   ' Note: Pluto's orbit is centred at OFFSET of 56, -73 to simulate ellipse.

FOR i=1 TO 10   'incl moon when i=10
   READ pname$(i), dist(i), pper(i), pang(i)  
         '1st pang(i) (starting date) is init pos of planets on JAN 31/25.
   ovel(i)= -360/pper(i)   'orbital vel.(degrees/day) (**is ccw) ============== 
NEXT i

' STARTUP DATE =================================================
yr=2025        'starting date (day #1)
m=1              ' Start date is Jan 31/2025
d=30 ! day=0      ' 1 is added to date & day# on 1st iteration of  "main:"  loop.
STEP=1     'default

'c'
 sw=SCREEN_WIDTH() ! sh=SCREEN_HEIGHT()    ' 1024 x 724 ****For iPad Mini****
 sw2=sw/2-100 ! sh2=sh/2   '100 left of centre screen, to allow room for Pluto's orbit
 dscale= .8         ' scale for drawing circles (orbits) 

50
TEXT CLEAR
PRINT "Do you want to enter Stop date? y/n" ' if you want to stop at given date
INPUT y$ ! y$=LOWSTR$(y$)
IF y$<>"y" AND y$<>"n" THEN GOTO 50

55
IF y$="y" THEN 
  TEXT CLEAR
  PRINT "Enter date (day) " ! INPUT dsp    ' stop date
  PRINT "Enter month# "     ! INPUT msp 
  PRINT "Enter year (yyyy)" ! INPUT ysp  
  IF dsp>31 OR msp>12 OR ysp<2025 THEN GOTO 55    ' error check
ENDIF

''
GRAPHICS
FILL COLOR 1,0,0
BUTTON "toggle" TEXT "STOP" AT sw-200, sh-80 SIZE 130,70

SLIDER "scale" VALUE 0 AT 1000, 600 SIZE 400 ANGLE -90     ' for dscale
SLIDER "speed" VALUE 0 AT 20, 600 SIZE 400 ANGLE -90       ' for display speed

y$="n"
dsc=0   'initial scale

'g'================= MAIN LOOP ============================

main:
REFRESH OFF ' stops flicker - don't update screen during calculations, 
GRAPHICS CLEAR 0, 0, .3     'very dark blue

'Heliocentric Longitude markers ---------------------
DRAW LINE sw2+250,sh2 TO sw2+330, sh2 ! DRAW TEXT "0º" AT sw2+335,sh2-10
DRAW LINE sw2-250,sh2 TO sw2-330, sh2 ! DRAW TEXT "180º" AT sw2-380,sh2-10
DRAW LINE sw2,sh2-250 TO sw2, sh2-300 ! DRAW TEXT "90º" AT sw2-13,sh2-320
DRAW LINE sw2,sh2+250 TO sw2, sh2+315 ! DRAW TEXT "270º" AT sw2-18,sh2+320

sv2=SLIDER_VALUE("speed")

IF sv2<=0.2 THEN       ' The lower part of the slider range controls the PAUSE duration (at the
   STEP=1                      ' end of the main: loop), allowing a slower                                  
   pdelay=24*(sv2-.2)^2   ' display speed for the inner planets.
ENDIF
                                        ' The upper part of the slider range varies the STEP, i.e.                                   
IF sv2>.3 THEN                   'how many days pass for each iteration of the loop,
    DRAW COLOR 1, .5, .5     'allowing a higher display speed for the outer planets.
              'NOTE: if STEP> ~15 or 20 the accuracy will be reduced.

    DRAW TEXT "*STEP IS " & INT(STEP) & " DAYS" AT 40,450     'WARNING message:
                                                 ' if STEP >than ~20 days, accuracy will be reduced.
    DRAW COLOR 1,1,1   
    pdelay=0               ' pause (at end of main: loop)                
    STEP=INT(MAX(1,200*(sv2-.3)^2))
ENDIF                       

dstp=dsp-d      ' scale
      ' DRAW TEXT sv2 AT 40,400    'only if you want to display it
DRAW LINE 1, 510 TO 50,510      'just a marker for change of STEP mode.

'r' 
' DATE CALCULATION: ===================
d2=day
day=day+STEP    ' day# from start

400
d=d+1     ' date - of month
days(2)=28         ' reset to default after leap year

IF m=2 AND yr1=INTEG(yr1) AND yr1/100<>INTEG(yr1/100) THEN days(2)=29      'is leap year

IF d>days(m) THEN     ' next month
    m=m+1 
    IF m>12 THEN   ' next year
       m=1             ' reset month to Jan
       yr=yr+1        '   next year 
    ENDIF 
    d=1         ' reset date
ENDIF

' this part is to keep date in step with skipped days when STEP>1:   ==================
IF dsp=d AND msp=m AND ysp=yr THEN g=1   'stop date.  
d2=d2+1
IF d2<day AND g=0 THEN 400    'if skipped days not caught up & not stop date 
' =======================================================================
'g'

DRAW TEXT INT(d) & " " & mon$(m) & " " & yr AT sw-160, 60
DRAW TEXT "Day#= " & INT(day) AT sw-160, 30 
DRAW TEXT "ZOOM" AT sw-60,200
DRAW TEXT "SPEED" AT 5,200

'-------------------------------- 
dsc=dscale*(SLIDER_VALUE("scale"))+.03     ' distance scale factor for drawing
FILL COLOR 1,1, 0              ' yellow, for sun
FILL CIRCLE sw2, sh2 SIZE 25*dsc         'Sun, variable size, according to zoom 
DRAW COLOR 1,1, 1        ' white, for planets & orbits

' ===== ORBITS -------------------------------------
FOR i=1 TO 8
  DRAW CIRCLE sw2,sh2 SIZE dist(i)*2*dsc    'draw orbits of 8 planets
NEXT i

'Pluto's orbit is elliptical; depict as off centre circle:
poffx=56 ! poffy=-73    'these variables make it easier to adjust all pxoff & pyoff's
DRAW CIRCLE sw2+poffx, sh2+poffy SIZE 5900*2*dsc 

'b' ===== PLANETS ========================   
FOR i=1 TO 10
  FILL COLOR 1,1,1               'white, for planets
  IF i=3 THEN FILL COLOR .2, .2, 1  'blue, for Earth only
  IF i=4 THEN FILL COLOR 1, .5, .5  'reddish, for Mars only
  IF i=7 THEN FILL COLOR .4, 1, .4  'greenish, for Uranus only
  pang(i)=pang(i)+ovel(i)*STEP 'new angular pos each day (or each STEP in FOR loop)

  IF pang(i)<0 THEN pang(i)=pang(i)+360    ' Make angle positive (for MOD to work)
                                                    ' and just keep the numbers smaller
  pang(i)=pang(i)%360         '  a%b is  a MOD b (not documented)
  sz=8           'planet size       
  IF i<=4 OR i=9 THEN sz=4    ' inner planets & Pluto are smaller
  
   IF i=9 THEN    'Pluto
          pxoff=poffx ! pyoff=poffy     'pluto offset, to simulate ellipse
   ELSE
        pxoff=0 ! pyoff=0
   ENDIF 
   
' Planets only: dsc is the drawing scale

 IF i<=9 THEN  
   x(i)=dist(i)*2*COS(pang(i))*dsc + pxoff       ' dist to planet from sun; x position
   y(i)=dist(i)*2*SIN(pang(i))*dsc + pyoff 
   FILL CIRCLE sw2+x(i), sh2+y(i) SIZE sz        'draw planets
   DRAW TEXT LEFT$(pname$(i),2) AT sw2+x(i), sh2+y(i)+8  'place below planet
 ELSE          ' i=10 is the moon  
   DRAW CIRCLE sw2+x(3), sh2+y(3) SIZE dist(10)*2*dsc  'MOON ORBIT, ctr on Earth

' MOON POS'N: ----------
   x(10)=sw2+x(3)+dist(10)*2*COS(pang(10))*dsc  'posn in orbit at pos'n of Earth
   y(10)=sh2+y(3)+dist(10)*2*SIN(pang(10))*dsc 
   FILL CIRCLE x(10),y(10) SIZE 5*dsc  'at current posn of Earth plus dist from Earth
  ENDIF
NEXT i

REFRESH ON  'now update the screen
PAUSE pdelay   'for low speed - pdelay is set by Slider("speed")

500
IF BUTTON_PRESSED("toggle") THEN g=1-g   ' toggle Stop/Go & button text

IF g=1 THEN
   BUTTON "toggle" TEXT "GO" 
   PAUSE .5     ' to avoid double tap
   GOTO 500
ENDIF

BUTTON "toggle" TEXT "STOP"
    'PAUSE .7  'only for testing.     
IF dsp=d+1 AND msp=m AND ysp=yr THEN g=1     'stop date, so stop

GOTO main
'====================================

DEF dbp ! DEBUG PAUSE ! END DEF  'this is helpful for debugging
END

''
 

[Henko]

Hi Davey,
After copying the source and running it, i got 3 consequtive error messages.
The starting combi /* had to be inserted at the beginning of the file,
In the section “Planets”, there were missing statements “end if” and “next i”.
Adding these made the progam run nicely .

[smbstarv]

Where should these missing next and endif''s be inserted....?

[Henko]

Code: Select all

' MOON POS'N: ----------
   x(10)=sw2+x(3)+dist(10)*2*COS(pang(10))*dsc  'posn in orbit at pos'n of Earth
   y(10)=sh2+y(3)+dist(10)*2*SIN(pang(10))*dsc 
   FILL CIRCLE x(10),y(10) SIZE 5*dsc  'at current posn of Earth plus dist from Earth

  end if     ' insert here
next i       ' insert here

REFRESH ON  'now update the screen

[davey110]

Thank you for trying it out. I have updated the listing to show the corrections, (just before the REFRESH ON statement). I must have accidenally deleted these during the transferring from my listing to the Forum. (I did some minor editing after transferring).

I have changed the formulas for interpreting the SLIDER("speed") values (near the start of the "main:" loop), and also deleted the "intermediate" part of that routine, as it didn't really make much difference. The "speed" slider now calculates the display speed non-linearly in both upper and lower parts of it's range. This gives a smoother control of the speed. You'll see there is a gap between slider values 0.2 and 0.3 (in the IF statements). Nothing happens in this range - it just makes it easier to set the minimum pdelay (PAUSE) without starting to skip days (STEP), the same as the part I deleted did. (If you want to play with these equations, a graphing calculator is indispensable. There are apps for some.)

You also may notice that Pluto's orbit changes with zoom. To correct this, it's "offset" would have to vary with the the zoom, instead of remaining constant.. I didn't think that was worth the effort. Have a go at it if you like.

Let me know if you have any suggestions.

[davey110]

I have made a small revision to colour the Stop button red [Add: SET BUTTONS CUSTOM (near the top) and FILL COLOR 1,0,0 (where the button is created)].

[Chooch912]

First- thank you for educating me with a new vocabulary word: Orrery.
Second, this is truly a work of art so thank you for not only creating it but sharing it.

I am trying to learn more about how this works by looking at each line of code (not always easy for an 80 year old whose only programming language background is "Business Basic" from the 1980's).