Nine planets, nine colours

Where the nine hues come from

Classical texts give every graha a fixed colour: the Sun copper red, the Moon white, Mars blood red, Mercury grass green, Jupiter golden yellow, Venus iridescent white, Saturn dark blue, and the two lunar nodes smoky and ash grey. These assignments are centuries old and appear in every standard source. That was this project's stroke of luck: nine planets give nine tones, they spread almost evenly around the wheel, and there are exactly as many as an editor needs for syntax. No tone had to be invented.

Where each colour's force comes from

A graha can stand strong or weak in a chart — depending on the sign and the house it occupies. That strength decides the saturation here, but only within what the prescribed hue allows. Five cases from this chart, three of them evidence and two objections:

• Venus stands in its most favourable sign, Pisces. That is called exalted, and it is the strongest placement there is. It is also atmakaraka, the planet at the highest degree, which the tradition reads as the most important of the chart. Its turquoise therefore sits at the limit: no more saturated is possible at that lightness.
• Jupiter stands in the first house. For Jupiter that is the best position imaginable, called dig bala, literally directional strength. Its gold sits at the limit too. In the two light variants Sūrya reaches it as well — less headroom is left there, and three colours hit the ceiling at once.
• Rahu is not a body but a crossing point, and counts as smoky and diffuse. It stays pale, under thirty per cent in every variant.
• Saturn and Mars both stand in the twelfth house, the house of withdrawal and of what is hidden. Both should therefore be held back. Saturn does sit below Mars in every variant — but Mars stays in the upper middle at seventy to seventy-four per cent. For Mars the rule does not hold, and the ladder shows it rather than passing over it.
• The Moon is where the rule ends. It stands exalted and should therefore be forceful. But its classical colour is white, and white carries no saturation. The hue comes first; strength cannot push past it.

Why there are two grounds

The background is the largest area on the screen. It should therefore come from whatever this chart clusters most clearly — and there were two ways to read that.

The first counts signs: five of the nine grahas stand in earth signs, in Taurus and Virgo. Earth gives a warm, brownish ground. Those are the Pratipada and Ushas variants.

The second takes the lagna, the ascendant: the sign rising on the eastern horizon at the moment of birth. The tradition holds it to be the sign of outward appearance. Here it is Libra, an air sign. Air gives a cool, clear ground — Swati and Tula.

The second path is in fact better founded: if any part of a chart decides visible form, it is the first house. Taurus and Virgo, by contrast, fall into the eighth and twelfth houses in this chart, the two most hidden ones — and they do so only because of this lagna. It is just that the warm ground simply looks good. So both stayed.

Why the lightness values are not freely chosen

Finding colours that go together is one half of the work. The other is that the text still has to be readable afterwards. The web accessibility guidelines put a number on it: body text needs at least 4.5 times the lightness difference to its background. Many well-known schemes fall short of that in the comments, of all places.

Here every colour that can carry text is computed to exactly that value — and against all three background layers, not only the darkest. So the hue comes from the chart, the lightness from the arithmetic. Together they make the colour.