The constellations of the zodiac

What is the Ecliptic?

As Earth orbits the Sun, the apparent position of the Sun against the background of stars changes continuously.

The path that the Sun travels across the celestial sphere is called the ecliptic. The constellations located along this path are called the zodiac constellations.

Interestingly, the constellation that the Sun is passing through during a given month cannot be observed at night during that month because it lies in the same direction as the Sun.

Why Are There Actually 13 Constellations?

Ancient peoples divided the ecliptic into 12 equal parts for the purposes of calendrics and astrology.

However, modern astronomy defines constellations as regions of space with specific boundaries. According to this definition, the ecliptic passes through an additional constellation:

Ophiuchus (Serpent Bearer)

located between Scorpius and Sagittarius.

Therefore, the ecliptic actually cuts through 13 constellations.

The 13 Zodiac Constellations

• Aries (The Ram)
• Taurus (The Bull)
• Gemini (The Twins)
• Cancer (The Crab)
• Leo (The Lion)
• Virgo (The Virgin)
• Libra (The Scales)
• Scorpius (The Scorpion)
• Ophiuchus (The Serpent Bearer)
• Sagittarius (The Archer)
• Capricornus (The Sea-Goat)
• Aquarius (The Water-Bearer)
• Pisces (The Fish)

Notable Constellations

Taurus (The Bull)

One of the most beautiful constellations in the night sky.

Contains:

• The star Aldebaran.
• The Hyades star cluster.
• The Pleiades star cluster (Seven Sisters).

Leo (The Lion)

Easily recognizable by its sickle-like shape.

Its brightest star is Regulus.

Scorpius (The Scorpion)

Prominent for its curved shape resembling a scorpion's tail.

The red star Antares is its most easily identifiable bright point.

Sagittarius (The Archer)

Located in the direction of the Galactic Center, it is the richest region of the sky in nebulae and star clusters.

Two Commonly Confused Names

Scorpius is not "Thần Nông"

The Latin name of this constellation means Scorpion. The designation "Thần Nông" does not originate from Western astronomical tradition.

Sagittarius is not "Nhân Mã"

Sagittarius means The Archer.

The constellation that actually represents a centaur is Centaurus, which does not lie on the ecliptic.

Zodiac Constellations and Zodiac Signs Are Not the Same

This is the most common point of confusion.

• Zodiac constellations are real regions in the sky defined by astronomy.
• Zodiac signs are a system of 12 equal divisions used in astrology.

These two systems share the same names, but they are not the same thing.

🌌 The zodiac constellations help us determine the apparent path of the Sun across the sky. From the perspective of modern astronomy, the ecliptic passes through 13 constellations, with Ophiuchus being the most frequently overlooked.

Further reading

• Why astrology is not a science
• Solar and lunar eclipses: two asymmetrical obscuration phenomena
• Auroras: light emitted by Earth's own atmosphere