Over the millenia, humans have developed a variety of ways to communicate. We use everything from vocalizations, facial expressions and body movements to graphic displays such as alphabets and numbers to make ourselves understood. Numbers are a very versatile tool and part of our everyday life. From simple math to computers, from social insurance numbers to bank machines - we rely heavily on numbers.
Numbers also play a huge part in science through the use of values and formulae. With them, the fathers of astronomy - Galileo, Newton and Einstein, among others - helped explain the cosmological mysteries of their day and laid the stepping stones for today's new age astronomy. In 1772 Johann Bode drew attention to the earlier work of J.D. Titius. Titius helped unravel the mystery of planetary distances from the Sun (by then proven to be at the centre of the solar system).
The Titius-Bode Law relies on a simple method that anyone can relate to and understand. Take the numbers 0, 3, 6, 12, 24, 48, 96, 192, 384 and 768, each of which (apart from the first) is double the value of its predecessor. Add 4 to each number and divide by 10, then note the similarity between the computations and the actual distances of the planets from the Sun in astronomical units (1 a.u. = the Sun-Earth distance of 150,000,000 km). Let's see how the numbers compare:
| Planet | T-B Law | Actual |
| Mercury | 0.40 | 0.39 |
| Venus | 0.70 | 0.72 |
| Earth | 1.00 | 1.00 |
| Mars | 1.60 | 1.52 |
| Asteroid Belt | 2.80 | (approx. correct) |
| Jupiter | 5.20 | 5.20 |
| Saturn | 10.0 | 9.54 |
| Uranus | 19.6 | 19.2 |
| Neptune | 38.8 | 30.1 |
| Pluto | 77.2 | 39.4 |
As you can see the law works pretty well except for Neptune and Pluto. It almost seems that Pluto is riding the track of Neptune's orbit. Somehow in its formation 4.5 billion years ago Neptune never reached its correct distance. Could the mighty gravitational attraction of Jupiter and Saturn have helped drag Neptune to a closer orbit? And what of little Pluto, with its highly elliptical orbit that at times circles the Sun closer than Neptune. My guess is that Pluto was a satellite of Neptune and through some cosmic whatnot Neptune broke from its intended orbit of around 38 a.u. to its present 30 and Pluto got separated from its mother.
How else can we explain Pluto as a planet when Mercury, Venus, Earth and Mars are rocky, whereas Jupiter, Saturn, Uranus and Neptune are gas giants? Pluto is a rocky planet for all intents and purposes, so it does not fit the sequence of early formation. And what of the asteroid belt at 2.8 a.u. distance. Looks like a right place to put a planet, but all that's left is rubble.
When all is said and done the Titius-Bode Law is exactly what it looks like - a numbers game we can all play with and use to learn the value of the mighty digit.