Moon Sign and Birth Star Calculator

What are Moon Signs and Birth Stars?

In Vedic astrology, the Moon Sign (Rasi) and Birth Star (Nakshatra) are crucial elements of an individual's birth chart. The Moon Sign represents the zodiac sign in which the Moon was positioned at the time of birth, while the Birth Star is a more precise lunar mansion within that sign.

The Formula for Calculating Moon Sign and Birth Star

The calculation of Moon Sign and Birth Star involves determining the Moon's position in the zodiac at the time of birth:

For Moon Sign (Rasi):

\[MoonSign = \lfloor \frac{MoonLongitude}{30^\circ} \rfloor + 1\]

For Birth Star (Nakshatra):

\[BirthStar = \lfloor \frac{MoonLongitude}{13^\circ20'} \rfloor + 1\]

Where:

• \(MoonLongitude\) = the ecliptic longitude of the Moon at the time of birth
• \(\lfloor \rfloor\) represents the floor function (rounding down to the nearest integer)

Step-by-Step Calculation

1. Convert the birth time to Universal Time Coordinated (UTC)
2. Calculate the Moon's longitude at the time of birth using astronomical algorithms
3. Apply the formulas above to determine the Moon Sign and Birth Star

Example Calculation

Let's say the Moon's longitude at the time of birth is 78°30':

1. Moon Sign: \(\lfloor \frac{78.5^\circ}{30^\circ} \rfloor + 1 = \lfloor 2.616 \rfloor + 1 = 2 + 1 = 3\) (Gemini)
2. Birth Star: \(\lfloor \frac{78.5^\circ}{13^\circ20'} \rfloor + 1 = \lfloor 5.887 \rfloor + 1 = 5 + 1 = 6\) (Ardra)

Visual Representation

This diagram represents the Moon Sign (Gemini) and Birth Star (Ardra) for our example calculation.