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

 
 g' 
/*
This program is an "Orrery". Look it up. 😊
Version 2: misc improvements: Pause, improved scaling, 2-digit year input

    Although this program shows the planets positions reasonably accurately on any particlar 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 & 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 Neptunes 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.
  ===========================================================    
  
 RAW DATA from an astronomy handbook; only used for ref when writing program:
 
   	 Dist(millions-km)   Revolution(days)
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.
  Pluto Long of Perihelion = 224º

*/ '=============== 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: 
	'	Dist(mill km) RevPer'd(d)  Start date is initial pang() of 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: Plutos 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.
         ' Note: initial pang() (planet angle) is stang() (starting angle)====
   
   ovel(i)= -360/pper(i)   'orbital vel.(degrees/day) (**is ccw) ============== 
NEXT i
   
' STARTUP DATE =================================================
yr=2025  'starting date (day #1); replaces stdate(), stmon() etc above 
m=1            ' Start date is Jan 31/2025
d=31 ! 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
 sw2=sw/2-50 ! sh2=sh/2  ' 50 left of centre screen, to allow plutos 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$="y" THEN 
  TEXT CLEAR
  PRINT "*NOTE:  STOP DATE MUST BE AFTER  31 JAN, 2025! *"
  PRINT "Enter date (day):  "; ! INPUT dsp ! PRINT dsp       ' stop date
  PRINT "Enter month #:     "; ! INPUT msp ! PRINT mon$(msp) 
  PRINT "Enter year (yy or yyyy):  "; ! INPUT ysp 
  IF ysp<100 THEN ysp=ysp+2000 ! PRINT ysp ! PAUSE 2  ' allows 2-digit year for 2000's 
  IF dsp>31 OR msp>12 OR ysp<2025 THEN GOTO 55  ' partial error check
  'y$="n"
ENDIF

''
GRAPHICS
FILL COLOR 1,0,0   ' for button colour
BUTTON "toggle" TEXT "PAUSE" AT sw-200, sh-80 SIZE 130,70
SLIDER "scale" VALUE 0.2 AT 1000, 600 SIZE 400 ANGLE -90     ' for dscale
SLIDER "speed" VALUE 0.1 AT 20, 600 SIZE 400 ANGLE -90

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")   'orbital speed

IF sv2<=0.2 THEN       ' The lower part controls the PAUSE duration (at the
   STEP=1                ' end of the loop), allowing a slower                                  
   pdelay=24*(sv2-.2)^2  ' display speed for the inner planets.
ENDIF

IF sv2>.3 THEN   'The upper part of the slider range varies the STEP, ie
                 'how many days pass for each iteration of the loop,
                 'allowing a higher display speed for the outer planets.
             ' *NOTE: if STEP> ~15 or 20 the accuracy will be reduced.*
    DRAW COLOR 1, .5, .5                       
    DRAW TEXT "*STEP IS " & INT(STEP) & " DAYS" AT 40,450   'WARNING msg:
                                ' if STEP >than ~20 days, accuracy may 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      
IF y$="y" AND yr=ysp AND m=msp-1 THEN STEP=1  ' slow down before stopping,
                                                    ' so not to miss stop date.
'DRAW TEXT sv2 AT 40,400    'if you want to display it
DRAW LINE 1, 510 TO 50,510  'just a marker for change of STEP.

'r'-----------------------------------
' DATE CALCULATION: =========--=-=-=-=-=-=-=-=-=-=
IF g=1 THEN GOTO 100  ' paused - don't increment date or planet positions

d2=day
day=day+STEP    ' day# from start
400
d=d+1     ' day 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 try 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'
100
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
SET BUTTONS CUSTOM

'-------------------- SCALE ------------ 
'FILL COLOR 0, 0, .3 
'dsc=dscale*.3*(SLIDER_VALUE("scale"))+.024    
dsc=dscale*.95*(SLIDER_VALUE("scale"))^2+.03      ' display scale factor 

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
  
  IF g=0 THEN 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)
  pang(i)=pang(i)%360   ' a%b is  a MOD b
  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
   y(10)=sh2+y(3)+dist(10)*2*SIN(pang(10))*dsc 
   FILL CIRCLE x(10),y(10) SIZE 5*dsc 'centred at current posn of Earth+dist from E
 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 Pause/Go & button text

IF g=1 THEN
FILL COLOR 0,.8, 0
   BUTTON "toggle" TEXT "GO" 
   PAUSE .5
ENDIF

FILL COLOR 1,0,0
IF g=0 THEN BUTTON "toggle" TEXT "PAUSE"

'PAUSE .7  'only for testing.     
IF dsp=d AND msp=m AND ysp=yr THEN g=1   'stop date so stop/pause. 
  
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).

[davey110]

Chooch912- I'm coming up 90 in 2 months, so keep on programming! If you need any explanations in Solar System I'll be happy to help.

My introduction to BASIC was in the 1970's on a time-share IBM main-frame computer with input and paper output on a teletype machine, and we saved our program on (and loaded from) punched tape.

[davey110]

I have posted Version 2 of SolarSystem.sb in the original post, with the following changes that I hope are improvements:

- smoother scaling, especially for the outer planets.

- Stop/Go button is now a Pause/Go button. This allows adjusting of Scale & Speed while paused or stopped at a Stop Date. Go will restart it from that point. (I found this necessary in order to see a conjunction of an outer planet e.g. Uranus on 17 May/25, or when an outer & inner planet are close together in the sky),

- Year of stop-date in this century can be input as 2 or 4 digits.

Note that if STEP is more that 1, it could skip over a stop date. Hence the warning message.

The centre of Pluto's orbit shifts with scale. It could be fixed by scaling it's offset, but it's hardly worth the trouble for the small scale range that it's on-screen.
BTW I am using an iPad mini. I don't know if that affects the display or not. If it does, you'll have to figure out the corrections required for a full-size display. The 2 sliders should be on the extreme left & right of the screen.

I have checked the program for accuracy using several future lunar and solar eclipses. The position of the moon tracks very well with where it should be on those dates. (The date can vary depending on what time zone you're in. The program is based on data for North America Pacific time).

Anybody is welcome to make any other changes you would like.