The planet that rules the sign where the Moon is placed in your birth chart is one of the most important planets as it governs the direction and flow of our thoughts and emotions.
The rulership of the signs are given below for reference.
Aries – Mars, Taurus – Venus, Gemini – Mercury, Cancer – Moon, Leo – Sun, Virgo – Mercury, Libra – Venus, Scorpio – Mars, Ketu, Sagittarius – Jupiter, Capricorn – Saturn, Aquarius – Saturn, Rahu, Pisces – Jupiter.
The sign where the Moon is placed gives us important clues about our mental configuration. But the planet that rules this sign will help us understand how we experience the world around us through emotions and thoughts. Because this planet controls our thoughts and experiences.
If this planet is exalted or placed well in the chart our thoughts are positive and auspicious, it leads us to the right actions. But if this planet is debilitated or placed negatively then it can cause a lot of trouble because it brings negativity and doubts into our thinking. It influences you to find faults based on the significations of that planet. It does not allow you to keep things simple and enjoy your life.
Example Moon in Taurus is considered one of the best positions for the Moon as Moon is exalted in Taurus. But if Venus the ruler of Taurus goes into the sign of Virgo where it is debilitated then the positives of Taurus Moon will become hard to manifest because of the debilitated Venus. The houses ruled by Venus and the natural significations of venus may get negative. We may not like to be associated with that planet and it’s significators.
So at this time it is important to remedy Venus.
If your Moon is ruled by the Sun – Your thoughts are enterprising, royal and creative, on the negative side it may also be egotistical in nature.
If your moon is ruled by Mars – you may feel mentally strong but you may also experience aggressiveness. The urge to execute plans without proper thinking can also happen.
If your Moon is ruled by Mercury it will give you business oriented thoughts. It will also make you light hearted and jovial if mercury is well placed in your chart.
if your Moon is ruled by Jupiter your thoughts may be noble and optimistic. It will lead you towards wisdom and knowledge. It can also give you great memory power.
If your Moon is ruled by Saturn you may experience gloomy and melancholic thoughts.
If your Moon is ruled by Venus, it gives you artistic and creative thoughts. It makes you very compassionate and loving. But remember this is true only if Venus is well placed in your chart.
If your Moon is ruled by Rahu it gives a lot of thoughts which pulls you in multiple directions and drain your energy. It creates lot of doubts and confusions.
If your moon is ruled by Ketu you may feel lack of interest in the material world and it could lead you to dispassion. Sudden thought impulses can prompt you to make mistakes so you have to be very careful.
What if Moon itself is the ruler of your Moon sign which happens to be the case if your Moon Sign is Cancer. In this case the strongest of the Moon’s nakshatra lord, Navamsha lord of the moon, Karaka of the house where the Moon is placed and Venus becomes the planet that directs the nature of your thoughts.
I learned this from Zoran who belongs to the tradition of Pandit Sanjay Rath.