Zodiac Basics: Signs, Elements and Houses

This is a fortune corner for fun. Unlike the other tests on Nadapge, it is not research-based and is separate from your analysis results.

Where astrology comes from

Western astrology began in ancient Babylon about 3,000 years ago, where changes in the sky were read as omens for kings and kingdoms. Later, in the Hellenistic world, where Greek and Egyptian ideas mixed, a new practice took shape: reading an individual person from the sky at the moment of their birth. In the 2nd century, the scholar Ptolemy summed up this approach in the Tetrabiblos, which served as a standard textbook for well over a thousand years.

Signs are not the same as constellations

The 12 signs of astrology are not the star patterns themselves. They are 12 equal slices of the ecliptic (the Sun’s yearly path across the sky), each 30° wide, counted from the March equinox. The first slice is Aries. This is called the tropical zodiac.

Earth’s axis slowly wobbles like a spinning top (precession), so the equinox point drifts by about 1° every 72 years. Over two thousand years, the signs and the constellations they were named after have slipped apart by roughly one whole sign. If you are a “late March Aries,” the Sun was most likely in front of the stars of Pisces when you were born. Ophiuchus, the “13th sign” that pops up in the news now and then, is a constellation the Sun does pass through, but it has never been part of the twelve 30° signs.

Your sun sign: set by your birthday

When people say “my sign,” they mean the sign the Sun was in on the day they were born.

Sign	Dates	Sign	Dates
Aries	3/21 ~ 4/19	Libra	9/23 ~ 10/22
Taurus	4/20 ~ 5/20	Scorpio	10/23 ~ 11/21
Gemini	5/21 ~ 6/20	Sagittarius	11/22 ~ 12/21
Cancer	6/21 ~ 7/22	Capricorn	12/22 ~ 1/19
Leo	7/23 ~ 8/22	Aquarius	1/20 ~ 2/18
Virgo	8/23 ~ 9/22	Pisces	2/19 ~ 3/20

The exact moment the Sun crosses into a new sign shifts a little from year to year, so if your birthday falls right on a boundary, your sign can differ by a day depending on the year.

Elements and modalities

The signs fall into four elements:

• Fire: Aries, Leo, Sagittarius
• Earth: Taurus, Virgo, Capricorn
• Air: Gemini, Libra, Aquarius
• Water: Cancer, Scorpio, Pisces

They also fall into three modalities. Cardinal signs open a season (Aries, Cancer, Libra, Capricorn), fixed signs hold its middle (Taurus, Leo, Scorpio, Aquarius), and mutable signs carry it into the next (Gemini, Virgo, Sagittarius, Pisces).

The 12 houses: areas of life

Astrology divides life into 12 areas, called houses.

1. Self and first impressions
2. Money, belongings and what you value
3. Communication, learning, siblings and short trips
4. Home and family
5. Fun, creativity and romance
6. Daily work and routines
7. Partners and one-on-one relationships
8. Shared resources and deep change
9. Study, travel and the big picture
10. Career and public image
11. Friends, groups and hopes
12. Rest and your inner world

How Nadapge builds your weekly horoscope

Nadapge uses solar houses. Your sun sign is treated as the 1st house, the next sign as the 2nd house, and so on around the circle.

1. Every 30 minutes from Monday 00:00 to Sunday 24:00 (Korea time), we work out which sign the Moon is in. The Moon changes sign every two to three days. We use a simplified version of the lunar longitude formula from astronomer Jean Meeus. Its error is well under one degree, which is plenty to tell which sign the Moon is in.
2. The house where the Moon spends the most time becomes the week’s main focus.
3. The house of the sign the Sun is currently in becomes the week’s background theme.

Everything is calculated, not random, so the same sign and the same week always give the same result.

Please keep in mind: there is no scientific evidence

In a double-blind study published in Nature, astrologers were asked to match people’s birth charts to their personality test profiles. They did no better than chance (Carlson, 1985). Data on more than 2,000 “time twins,” people born in London in 1958 within minutes of each other and followed for decades, showed no sign that they ended up more alike in personality or life outcomes than anyone else (Dean & Kelly, 2003).

So why do horoscopes often feel so accurate? A big part of it is the Barnum effect (also called the Forer effect): we tend to accept vague statements that fit almost anyone as if they were written just for us. In 1949, psychologist Bertram Forer gave his students what he said were personal profiles. Every student got the exact same text, and on average they rated it as a very good description of themselves (Forer, 1949).

Enjoy astrology as a piece of culture and a fun conversation starter, not a guide for important decisions. If you’d like to understand yourself better, give Nadapge’s evidence-based tests a try too.