Chapter 5 – Solar System Orbits (Solar Apex)

Orrery, simulates the scale and relative movement of the planets about the Sun
Bode’s Law
Kepler’s Orbits, demonstrates the first two of Kepler’s Laws
Orbit Foci, plotting the second focus
Comet Orbit, eccentric orbits
Halley’s Comet, depicts one complete orbit, 1948-2023
Pluto’s Orbit, plots the relative positions of Pluto and Neptune from 1880-2128, one complete orbit for Pluto
Solar Apex, corkscrew motion of a planet towards the Solar Apex.

Solar Apex

Even as you sit quietly at your Spectrum, you and, I hope, the whole room are moving rapidly across the universe. Nor are you moving constantly in a given direction but in a whole series of loops and whirling spirals. This series would read:

  1. Rotation about the Earth’s axis.
  2. Earth’s rotation about Earth/Moon axis.
  3. Earth’s rotation about the Sun.
  4. Sun’s rotation about the galaxy.
  5. Galaxy’s rotation about the Local Group of Galaxies (LG of G).
  6. LG of G rotation about the Virgo Super Cluster of Galaxies (VSCG).
  7. VSCG rotation about the universe.

Most astronomers and cosmologists theorise in this way, but categories 5 and 6 are pure speculation and category 7 improbable under currently accepted theories of the universe’s creation which conform to the idea of a Big Bang, where all groups of galaxies are still moving apart from the initial explosion. Of course if the universe is ‘closed’ and the galaxies finally come to rest they will probably reverse their motion back to the point of the Big Bang – in which case the galaxies are in orbit about this point even if their motion is in a straight line there and back (a maximum of one orbit only). A case of a shell falling back into the muzzle that fired it!

Down to Earth
The following program is a little less rarified and combines categories 3 and 4 to show the corkscrew motion of a planet towards a point in the sky, near the star Vega, called the Solar Apex. This is the direction in space in which the Sun is moving at a speed of 275 km/sec as it orbits our galaxy. The Sun is the straight line trace across the screen and the helical trace that of the planet, the orbit of which can be tilted at an angle for effect.

The various helices as PLOTted have a modest three-dimensional quality to them. Figure 5.13 is a typical example.

The two INPUT conditions control the orbit tilt, 1 for near edge-on, 10 for plan view whilst the planet INPUT alters the orbit radius. The period displayed is purely arbitrary and is controlled by the orbit radius merely to indicate that the helix will be finer and will occur in a shorter period of time on a smaller orbit.


10 CLS : PRINT “Solar Apex”,
15 PRINT “tilt =”;
20 INPUT “1 to 10″,z: PRINT z
25 PRINT ,”planet=”;
30 INPUT “1 to 5″,d: PRINT d,”period=”;: LET d=d*10: LET x=100
40 FOR f=0 TO PI*9 STEP .1
45 PRINT AT 2,23;INT (d*f)
50 LET a=x-f*5+x: LET b=f*3+d
60 PLOT INK 6; OVER 1;a,b
70 PLOT INK 4;a+SIN f*d,b+COS f*d/z
80 NEXT f

***NB the keen-eyed among you will notice that the ‘Period’ label in the image is located in the wrong place. This is because the code for this in Line 30 should read: …PRINT d’,”period=”;… not as shown in the listing. This is my mistake not the author’s.


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