Jupiter: the planet of expansion

When a particularly steady, bright point stands in the night sky and does not twinkle like the stars around it, it is usually Jupiter. Among the planets, only Venus regularly outshines it. That unhurried light earned the planet its reputation as far back as antiquity: large, kindly, well-meaning. Astronomy and astrology tell two quite different stories about the same celestial body – and both are worth hearing.

The giant among the planets

Not one of the eight planets comes anywhere near it. It is made mostly of hydrogen and helium, which puts it among the gas giants, and it weighs more than all the other planets put together. Measured right across the equator it is about 143,000 kilometres, roughly eleven times the diameter of the Earth. For all that bulk, it turns once on its axis in less than ten hours – fast enough to be visibly flattened at the poles. For one circuit of the Sun, by contrast, it takes almost twelve years.

A few further features set it apart from its neighbours:

• More than ninety confirmed moons, and the number rises with every better telescope. With a steadily held pair of binoculars you can pick out the four largest – Io, Europa, Ganymede and Callisto – as tiny points of light beside the planet.
• A huge magnetic field, which surrounds it far beyond its cloud cover and sends out strong radio emissions.
• A heat source of its own. It gives off more energy than it receives from the Sun, and so radiates from within.
• No solid ground. Anyone who wanted to land there would find nothing to land on, only ever denser layers of gas.

The storm that does not stop

The most striking feature is the Great Red Spot, a cyclone in Jupiter’s atmosphere that is larger than the whole of our Earth. It has been watched for centuries and it is raging still, even though it has shrunk measurably over the past few decades. A storm with no coast, no mountains, nothing at all that could slow it down: on a sphere of gas there is nothing for a vortex to wear itself out against.

Why the twelve years are useful in astrology

An orbital period of just under twelve years means roughly one year per zodiac sign. That makes Jupiter an agreeably clear timekeeper. About every twelve years it comes back to the place where it stood at your birth – at twelve, at twenty-four, at thirty-six and so on. This return counts as a moment when something opens: a new stretch, an opportunity, a setting out. What matters is the qualification that is added far too rarely in astrology: an opportunity is not yet a result. Whether you seize it is another matter.

The principle behind it: more of the same

In astrology this planet stands for expansion. Whatever it touches grows larger – the pleasant sides as much as the difficult ones. Its range of themes takes in confidence, generosity, the search for meaning, education beyond the bare learning of facts, law and justice, distance and the foreign. Classically it counts as the ruler of Sagittarius, and in the traditional scheme of rulerships as the ruler of Pisces as well. Anyone who studies the planets usually comes to know it as Saturn’s opposite number: the one expands, the other sets limits, and on its own neither of them reaches a usable result.

When the good one overdoes it

Its reputation as the “great bringer of luck” misses the point. A principle that enlarges also enlarges what does not fit: promises nobody can keep, spending nobody covers, the urge to be right dressed up as a worldview, the firm conviction that rules are something for other people. That is part of it too. A strong Jupiter placement in the chart therefore does not mean that everything falls into your lap, but that you have plenty of room to move – and room to move wants to be used and to be bounded.

How to find it in your chart

Three details are enough: which sign it is in, which house, and which aspects it forms. The sign says in what manner you expand, the house says in which area of life that happens, and the aspects show what this growth works together with. Once a calculated chart is in front of you, that is settled in five minutes. Experience shows that people recognise themselves in this one placement quite clearly – sometimes more clearly than they would like.