Aries constellation is located in the northern hemisphere. Its name means “the ram” in Latin. The symbol for the constellation is ♈ and it represents a ram’s horns. The constellation is usually associated with the story of the Golden Fleece in Greek mythology. Like other zodiac constellations, Aries was first catalogued by the Greek astronomer Ptolemy in the 2nd century.
Aries contains several notable deep sky objects, among them the unbarred spiral galaxy NGC 772 and the dwarf irregular galaxy NGC 1156.
FACTS, LOCATION & MAP
Aries is the 39th largest constellation in the sky, occupying 441 square degrees. It lies in the first quadrant of the northern hemisphere (NQ1) and can be seen at latitudes between +90° and -60°. The neighboring constellations are Cetus, Perseus, Pisces, Taurus, and Triangulum.
The constellation has five stars with known planets and contains no Messier objects. The brightest star in Aries is Hamal, Alpha Arietis. There are several well-known meteor showers connected to this constellation: the May Arietids, Autumn Arietids, Delta Arietids, Epsilon Arietids, Daytime-Arietids, and Aries-Triangulids.
Babylonians identified Aries as the agrarian worker, the last stop on the ecliptic. The name of the constellation later changed to Ram, but why Babylonians changed it is uncertain. In the 7th century BC, Neo-Babylonians did a revision of the Babylonian zodiac that placed Alpha Arietis, Hamal, very close to the vernal equinox, which is how Aries came to be so prominent among the zodiac signs in astrology.
In those times, Aries contained the equinox, the point at which the Sun crosses the celestial equator from north to south. Because of precession (slow wobble of Earth’s axis), the vernal equinox is no longer in Aries, but in Pisces. In 130 BC, however, it was located just south of Gamma Arietis (Mesarthim) and was taken to be the starting point of the zodiac.
In Greek myth, Aries is identified with the golden ram that rescued Phrixus and took him to Colchis, where he sacrificed the ram to the gods. The ram’s skin that he placed in a temple was the Golden Fleece, which later appears in the story of Jason and the Argonauts.
Phrixus was the son of a Boeotian king. He had a twin sister, Helle. The children had a stepmother, Ino, who hated them and wanted to get rid of them. She came up with a plan to put the land of the brink of famine by making sure the wheat crops failed. When a man was sent to consult the Oracle at Delphi, Ino bribed him to lie and say the Oracle asked for the king’s children to be sacrificed if they did not want the people to starve.
Phrixus and Helle were about to die when a winged ram with golden wool came to their rescue. The ram was sent by their real mother, the cloud nymph Nephele. It took both children and flew east to Colchis. Only Phrixus survived the journey. Helle fell off the ram and drowned in the Dardanelles. The strait was later renamed to Hellespont, or sea of Helle, in her memory.
Phrixus was welcomed by King Aeëtes of Colchis, to whom he presented the Golden Fleece. In return, the king gave Phrixus his daughter Chalciope’s hand.
MAJOR STARS IN ARIES
Hamal – α Arietis (Alpha Arietis)
Hamal is the brightest star in the constellation Aries and the 48th brightest star in the night sky. It is a K-type orange giant about twice as massive as the Sun, with an apparent magnitude varying between 1.98 and 2.04.
The star is 66 light years distant. Between 2000 and 100 BC, Hamal was located at the vernal equinox, the point that marks the beginning of spring.
The name Hamal means lamb and derives from the Arabic phrase rās al-ħamal, meaning “head of the ram.”
Sheratan – β Arietis (Beta Arietis)
Sheratan, Beta Arietis, is a white main sequence star and a spectroscopic binary, 59.6 light years distant. The companion is suspected to be a G class star. Sheratan has a visual magnitude of 2.64. The name comes from the Arabic phrase aš-šarāţān, which means “the two signs,” and refers to the vernal equinox, which the star marked together with Gamma Arietis a few thousand years ago.
Mesarthim – γ Arietis (Gamma Arietis)
Mesarthim, Gamma Arietis, is a triple star system. The origin of the name Mesarthim has been lost. The star has also at times been referred to as the First Star in Aries because at one point it was the nearest visible star to the point of the vernal equinox.
Gamma Arietis includes a binary star system composed of two white A-type main sequence stars with apparent magnitudes of 4.75 and 4.83, lying 7.7 arc seconds apart, and a third component, a magnitude 9.6 K-type star that lies 221 arc seconds away. The system is approximately 160 light years distant. The brightest component is classified as an Alpha-2 Canum Venaticorum type variable star, a chemically peculiar main sequence star with strong magnetic fields and strong strontium, chromium, or silicon spectral lines. The star’s brightness varies by 0.04 magnitudes with a period of 2.61 days.
Botein – δ Arietis (Delta Arietis)
Delta Arietis, also known as Botein, is an orange K-type giant star approximately 168 light years from Earth. It has an apparent magnitude of 4.35 and a diameter 13 times longer than that of the Sun. The star’s name is derived from the Arabic word butain, which means “belly.”
Bharani – 41 Arietis (c Arietis)
41 Arietis, sometimes also known as c Arietis, has the traditional name Bharani. The star was named after the second lunar mansion (division of the sky) in Hindu astrology. Bharani belongs to the spectral class B8Vn and is 160 light years distant. Its apparent magnitude is 3.61.
ε Arietis – Epsilon Arietis
Epsilon Arietis is a binary star, approximately 293 light years distant. It is composed of two white A-type main sequence dwarfs separated by 1.5 arc seconds. The components have apparent magnitudes of 5.2 and 5.5. The combined magnitude of the double star is 4.63.
DEEP SKY OBJECTS IN ARIES
NGC 772, or Arp 78, is an unbarred spiral galaxy in Aries. It is located about 130 light years from Earth and has an apparent magnitude of 11.3. The galaxy lies southeast of Beta Arietis.
Two supernovae were discovered in the galaxy, SN 2003 hl and SN 2993 iq. NGC 772 has a satellite galaxy, NGC 770. NGC 770 is an elliptical galaxy with an apparent magnitude of 14.2.
NGC 1156 is a dwarf irregular galaxy with an apparent magnitude of 12.3. The galaxy is classified as a Magellanic type irregular galaxy.
The galaxy’s core is larger than average and there are regions of contra-rotating gas inside it, believed to be the result of an interaction with another galaxy.
NGC 1156 lies northwest of Delta Arietis.
Other notable deep sky objects:
NGC 972 is a spiral galaxy located in the northern corner of the Aries constellation. It has an apparent magnitude of 12.1.
NGC 697 is another spiral galaxy in Aries, located northwest of Beta Arietis. It has a magnitude of 12.7.