Aries the Ram: First Sign of the Zodiac

Aries is a compact zodiac constellation that holds historical significance far exceeding its visual impact. For over two thousand years, it was the constellation containing the vernal equinox, the point where the Sun crosses the celestial equator in spring, making it the traditional first sign of the zodiac. Though its stars are modest, Aries is easy to find and connects to one of the great adventure stories of Greek mythology. Spot it with StarGlobe.

How to Find Aries

Aries sits between the brighter constellations Taurus to the east and Pisces to the west. Its three main stars, Hamal, Sheratan, and Mesarthim, form a compact curved line that is easy to identify once you know where to look.

One reliable method is to find the Great Square of Pegasus and look to the east. The first group of moderately bright stars beyond the eastern edge of the Square is Aries. Alternatively, start from the Pleiades in Taurus and look about 20 degrees to the west.

Hamal, at magnitude 2.0, is the brightest star and stands out in this relatively barren area of sky. The three main stars are arranged in a gentle arc about 5 degrees across.

The Stars of Aries

Hamal (Alpha Arietis) is an orange giant about 66 light-years from Earth. With a magnitude of 2.0, it is the 48th brightest star in the sky. In 2011, a planet was confirmed orbiting Hamal, a gas giant with at least 1.8 times Jupiter's mass in a 381-day orbit. Hamal's warm orange color is visible to the naked eye and contrasts nicely with its bluer companions.

Sheratan (Beta Arietis) is a white main-sequence star at magnitude 2.64, about 60 light-years away. It is a spectroscopic binary, meaning its companion star can only be detected through the regular Doppler shifting of its spectral lines as the two orbit each other every 107 days.

Mesarthim (Gamma Arietis) is a beautiful double star for small telescopes. It consists of two nearly equal white stars separated by about 7.5 arcseconds, making them easy to split at moderate magnification. Mesarthim was one of the first double stars discovered telescopically, noted by Robert Hooke in 1664.

Deep Sky Objects

Aries is not rich in bright deep sky objects, but it contains several galaxies accessible with larger amateur telescopes. NGC 772 is a spiral galaxy with a prominent arm extension caused by gravitational interaction with a smaller companion galaxy. NGC 1156 is a dwarf irregular galaxy at about 25 million light-years.

The constellation also lies near several galaxy groups that extend into neighboring Triangulum and Pisces, providing hunting grounds for dedicated galaxy observers with larger aperture telescopes and dark skies.

The First Point of Aries

Around 2,000 years ago, the vernal equinox (the point where the Sun crosses the celestial equator northward in March) lay within Aries. This is why Aries became the first sign of the zodiac in both Western astrology and ancient astronomical systems. The point is still called the "First Point of Aries" in astronomical terminology, even though precession has since moved it into Pisces, where it currently resides. It will eventually enter Aquarius.

This historical significance made Aries one of the most important constellations in the ancient world, despite its modest appearance. The vernal equinox was used to define the start of the year in many cultures, and Aries's position at this critical point gave it a prominence that endures in cultural memory.

Mythology and Cultural Heritage

In Greek mythology, Aries represents the golden-fleeced ram that rescued Phrixus and Helle from their wicked stepmother. The ram carried them through the air to Colchis on the shores of the Black Sea. Helle fell into the sea at a strait that was thereafter named the Hellespont (modern Dardanelles), but Phrixus arrived safely and sacrificed the ram in gratitude, hanging its golden fleece in a sacred grove.

The Golden Fleece later became the object of Jason's quest with the Argonauts, one of the most famous adventure stories in Greek mythology. In Chinese astronomy, several of Aries's stars formed part of the "Bond" constellation associated with official documents. In Hindu astronomy, Aries corresponds to Mesha, the first of twelve zodiac signs.

Best Time to Observe

Aries is best observed during November and December evenings, when it transits the meridian high in the sky. The constellation is visible from September through February. Its position north of the celestial equator makes it accessible from both hemispheres, though it is better placed for northern observers.

Neighboring Constellations

Taurus lies to the east, with the Pleiades cluster providing a bright landmark. Pisces sprawls to the west and south, while Perseus and Triangulum sit to the north. Cetus borders Aries to the south. Find these autumn constellations with StarGlobe.

Quick Facts

Aries covers 441 square degrees, ranking 39th in size. It has no Messier objects. Hamal shines at magnitude 2.0, and only three stars are brighter than magnitude 4.5. The constellation's right ascension ranges from about 1h 46m to 3h 29m, and its declination spans from about +10 to +31 degrees.