Expert Verified by: David Chen, Senior Astrological Data Analyst | Updated: May 2024
Discover your inner emotional landscape and the “mask” you present to the world. Our Moon Sign and Rising Sign Calculator provides precise calculations of your lunar position and Ascendant using your exact birth data and geographic coordinates.
Moon Sign & Rising Sign Calculator
Moon Sign and Rising Sign Calculator Formula
Ascendant (Rising Sign) Formula:
Asc = arctan(-cos(LST) / (sin(LST) * cos(ε) - tan(φ) * sin(ε)))
Moon Position: Calculated using simplified lunar series for Mean Longitude and Corrections.
Source: Wikipedia (Ascendant), Astrodienst
Variables:
- Birth Date/Time: Used to calculate the Julian Day and Universal Time (UT).
- Latitude (φ): Your vertical position on Earth, crucial for the Rising Sign.
- Longitude: Used to determine Local Sidereal Time (LST).
- Obliquity (ε): The axial tilt of the Earth (approx. 23.4°).
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What is a Moon Sign and Rising Sign Calculator?
While most people know their Sun Sign (based on birth month), the Moon and Rising signs offer a deeper look into your personality. The Moon Sign represents your subconscious, emotional needs, and how you react instinctively. It changes signs every 2.5 days, making it far more specific than the Sun.
The Rising Sign (or Ascendant) is the zodiac sign that was rising on the eastern horizon at the exact moment of your birth. It determines your physical appearance, first impressions, and your outward “persona.” Because the horizon rotates 360 degrees every 24 hours, the Rising Sign changes roughly every 2 hours.
How to Calculate Moon and Rising Signs (Example)
- Determine UTC Time: Convert your local birth time to Universal Time based on your timezone.
- Calculate Julian Date: Find the number of days since Jan 1, 4713 BC.
- Find Local Sidereal Time (LST): Calculate the position of the stars relative to your longitude.
- Apply Spherical Trigonometry: Use the LST and Latitude to find the degree of the Ascendant.
- Identify Zodiac Sign: Map the resulting degree (0-360) to the 12 signs (Aries through Pisces).
Frequently Asked Questions (FAQ)
Does birth time matter for the Moon sign? Yes, because the Moon moves quickly, being off by a few hours can change the sign entirely.
Why do I need my birth city? The city determines your Latitude and Longitude, which are the primary variables for calculating the Rising Sign.
What if I don’t know my exact birth time? You can estimate, but the Rising Sign might be inaccurate as it changes every two hours.
Is this the same as a Vedic calculator? No, this uses the Tropical Zodiac system common in Western Astrology.