Article
Moon sign
Pick a date. The card computes the Moon’s mean ecliptic longitude at UTC noon and splits it into 12 signs of 30°. 15 May 1990 is about 303.8° and Aquarius. 1 January 2000, near the J2000 epoch, is Scorpio. A sketch, not a full sky position.
The Moon sign calculator does this. It is entertainment and a tradition lesson, not a reading and not life advice.
The idea in brief
Pick a date. The card computes the Moon’s mean ecliptic longitude at UTC noon and splits it into 12 signs of 30°. 15 May 1990 is about 303.8° and Aquarius. 1 January 2000, near the J2000 epoch, is Scorpio. A sketch, not a full sky position.
You want a Moon sign. This card computes mean longitude at noon UTC and splits it into 12 signs of 30°. 15 May 1990 is about 303.8° and Aquarius. That is not the birth minute.
The Moon in a sign, and mean longitude
Moon-sign articles promise “the real feelings” under a Sun-sign shell. The Moon moves about 13 degrees a day, so without a birth hour it is easy to grab the neighboring sign.
Here the sketch is mean longitude at noon UTC, then a split into twelve 30° signs. 15 May 1990 is about 303.8° and Aquarius. 1 January 2000 is Scorpio. That is not an ephemeris at the birth minute.
Words on this page
The short forms below belong to this card only. Another page with a similar name may compute a different rule.
- mean longitude
- A sketch of the Moon on the ecliptic at noon UTC.
- 30°
- Each sign takes 30 degrees. 15 May 1990 is about 303.8° and Aquarius.
- J2000
- 1 January 2000, near the epoch, is Scorpio on this card.
Mean longitude, not a delivery-room minute
The Moon changes sign about every two and a half days. Without an hour, a noon sketch can miss a chart from 3:00.
Moon phase on the neighbor card does not use this longitude. It uses disk age from the 2000 new moon.
When this helps
| Situation | What the card shows |
|---|---|
| What Moon sign is 15 May 1990? | Aquarius, L ≈ 303.8°, air. |
| What about 1 January 2000? | Scorpio, near the J2000 epoch the formula starts from. |
| Will the hour change the sign? | Not on this card. The Moon's full position moves about 13° per day, so without an hour a neighbor is easy. Here it is noon UTC. |
How to read it
Aquarius and Air. L ≈ 303.8°, floor(303.8/30) = 10 counting from Aries.
Scorpio. L ≈ 218.3°, near the J2000.0 epoch the formula starts from.
Example from the card
303.8 degrees to Aquarius
You divide 303.8 by 30. floor gives 10. Index 0 is Aries, so 10 is Aquarius. 218.3° on 1 January 2000 falls in Scorpio.
Typical numbers from the card
| Question from the card | This card's answer |
|---|---|
| What Moon sign is 15 May 1990? | Aquarius and Air. L ≈ 303.8°, floor(303.8/30) = 10 counting from Aries. |
| What about 1 January 2000? | Scorpio. L ≈ 218.3°, near the J2000.0 epoch the formula starts from. |
| Is this a scientific forecast? | No. It is mean longitude without corrections. On a boundary an ephemeris can show another sign. |
Typical mistakes
| Mistake | What goes wrong | How to avoid it |
|---|---|---|
| You mix the Moon sign with the phase. | Phase is illumination. Sign is a slice of the ecliptic. | A full Moon in Scorpio is two different cards. |
| You compare with an ephemeris at 3:00 a.m. and call it an error. | Here it is mean longitude at noon UTC, not a minute position. | Treat it as a sketch. |
| You read Aquarius as "real emotions". | It is floor(L/30) in order from Aries. | Leave the soul story outside the formula. |
Before you treat the result as a reading
- 15 May 1990 ≈ 303.8° → Aquarius.
- 1 January 2000 → Scorpio.
- Time of day does not enter. It is noon UTC.
- This is not a moon phase and not a Sun sign.
Frequently asked questions
What Moon sign is 15 May 1990?
Aquarius and Air. L ≈ 303.8°, floor(303.8/30) = 10 counting from Aries.
What about 1 January 2000?
Scorpio. L ≈ 218.3°, near the J2000.0 epoch the formula starts from.
Is this a scientific forecast?
No. It is mean longitude without corrections. On a boundary an ephemeris can show another sign.
Does clock time change the result?
Not on this card. We take UTC noon on the chosen date. A birth-chart Moon needs an exact time.
How is this different from moon phase?
Phase is how much of the disc is lit in the synodic cycle. Here the sign comes from ecliptic longitude.
How is this different from the Sun sign?
The Sun sign uses day and month. This Moon-sign sketch uses L and moves about every two and a half days.