Local Group of Galaxies

Lights-up-in-the-dark three-dimensional model of the local group.

What it shows:

Three dimensional model of the local group of galaxies, with a scale of 1mm = 1kpc.

How it works:

A large wooden base board forms an x-y plane from which the approximate relative positions of the local galaxies are measured. The galaxies are LEDs and (for the two biggest, the Milky Way and Andromeda) 6V bulbs, mounted atop 8mm diameter plastic tubing; the length of the tube gives a z-axis position of the galaxy. The wires from the LEDs and bulbs run down the center of the tubing and are connected in parallel beneath the board. The circuit is connected in series with a 27W resistor and to a 6V DC supply. The whole board and the tubes are painted matt black so when viewed with the lights down, the lights float in space. Figure 1 gives an impression of the layout of the group in the x-y plane, and table 1 gives the coordinates of each galaxy in centimeters, x and y measured from the bottom right of the wood base.

figure 1. Plan of local group, looking onto x-y plane.

table 1. Location of galaxies of Local Group (1cm = 10kpc)

Galaxy Class x (cm) y (cm) z (cm)
Milky Way SBb 18 31 68
Leo 1 E3 14 16 89
Leo 2 E0 17 21 85
Fornax E3 15 25 52
LMC IR I 14 29 64
SMC IR I 14 32 63
Sculptor E3 17 31 64
Draco E3 22 33 71
Ursa Minor E5 22 32 71
NGC 6822 IR I 11 75 52
IC 1513 IR I 53 28 3
M31 Sb 80 38 44
NGC 205 E5 77 37 45
M32 E2 78 37 43
NGC 147 E5 81 38 54
M33 Sc 85 22 30
Maffei 1 S0 115 18 65
NGC 185 E3 82 36 53

Setting it up:

The board can be placed on the floor, although a turntable would give a changing perspective. Power is from a Damon 6V DC supply.


You can put labels on the model and use it with the lights up, and is probably more useful this way, but it gives you a neat feeling of space and depth with the lights out.


T. Ferris, Galaxies (Sierra Books, 1980) p.84