Star Constellation Facts: Capricornus, the Sea-Goat

Star Constellation Facts: Capricornus, the Sea-Goat
Alexander Jamieson’s Celestial Atlas (1822)

Capricornus, meaning “horned goat” in Latin, is the smallest of the zodiac constellations, as well as the second faintest after Cancer. Notice I called it the constellation Capricornus which is its proper astronomical name, and not Capricorn which is the name given to the astrological sign of the zodiac. This faint constellation’s brightest star, Deneb Algedi, is of magnitude 2.85, and is actually a multiple system whose primary component is a white giant star located 39 light-years distant.

Star Lore

Back in the year 149 CE there was an early Greek astronomer named Ptolemy who recorded 48 of the most common constellations of the time in his astronomical treatise called Almagest. Capricornus was amongst them, but its story can be traced all the way back to the Sumerians who settled the area (now called Iraq) between 5500 and 4000 BCE, and referred to the constellation as depicting a hybrid of a goat and a fish. Eventually the Greeks got a hold of the story, and tied it to the god of nature, Pan. Interestingly, in Greek mythology Cancer is known as the ‘Gate of Men’ where souls return to Earth to enter newborns, while Capricornus is known as the ‘Gate of the Gods’, where the souls of the dead return to heaven.

Represents: She-Goat

Although Capricornus is said to represent Amalthea, the she-goat that suckled Zeus as an infant, in some myths the constellation is also said to represent the half man half goat god called Pan. According to Greek legends, when Gaia, mother Earth, sent the monster Typhon to attack the Olympian gods, Pan suggested that they all transform themselves into animals in order to help them hide in plain sight of the Titans. Pan then took refuge in the Nile River, turning his lower half into a fish, and when he noticed that Typhon was attempting to destroy Zeus, he blew a shrill note on his pipes which made Typhon flee. Zeus later turned Pan into one of the signs of the zodiac in appreciation of his heroic deed.

Location: Southern Constellation

Capricornus: The Sea Goat

Capricornus is the 40th biggest constellation in the sky, and is visible for observers located between latitudes +60° and -90°. From northern latitudes Capricornus can be seen from July to November, and in the Southern hemisphere from winter to late spring, where its appears upside down relative to the Northern hemisphere.

Capricornus can be seen low on the southern horizon between Aquarius and Sagittarius and is located in an area of the sky known to the ancients as the Sea. This region is rich in constellations with water-related themes, such as Pisces, Piscis Austrinus, Aquarius, Eridanus, Cetus, Delphinus, and Hydra.

Shape: Triangular

Capricornus is one of the faintest constellations, which makes it even harder to discern the shape of a goat. From the Southern Hemisphere, it is possible to make out the shape of a rhinoceros horn, but from the far northern hemisphere, the constellation looks distinctly triangular, and appears more like a kite, or perhaps a Chinese fan.

Notable Stars: Deneb Algedi (2nd Magnitude)

Capricornus, the Sea-Goat– Deneb Algedi (Delta Capricorni), the constellation’s brightest star, is a multiple star system situated 39 light years distant with a visual magnitude of 2.85. It actually consists of four stars, with the most luminous component, Delta Capricorni A, being a white giant that is 8.5 times brighter than the Sun. Deneb Algedi derives from the Arabic phrase meaning “the tail of the goat”.

– Dahbi (Beta Capricorni), the second brightest star in Capricornus, is a star system found 328 light years from our solar system. Its primary components consist of Beta-1 Capricorni and Beta-2 Capricorni, with magnitudes of 3.05 and 6.09 respectively, which are 0.34 light years apart and orbit each other roughly every 700,000 years. However, Beta-1 Capricorni is actually a multiple stars consisting of at least three components, while Beta-2 Capricorni itself is also a double star. Dabih derives from the Arabic for “the butcher.”

– Algiedi (Alpha Capricorni), the constellation’s third brightest star, is a multiple star system located 690 light years from the Sun with a visual magnitude of 3.58. Its primary component, Alpha-1 Capricorni, is a binary system dominated by a yellow supergiant of magnitude of 4.30, while Alpha-2 Capricorni, is another binary system whose main star is yellow giant of magnitude 3.58. Algiedi derives from the Arabic for “the billy goat.”

Other stars of interest in Capricornus includes the blue-white giant Nashira (Gamma Capricorni); the white dwarf Dorsum (Theta Capricorni); yellow-white giant Psi Capricorni; the yellow giant Iota Capricorni; and the red giant Baten Algiedi (Omega Capricorni).

Notable Objects: Globular Cluster M30

Messier 30– Messier 30 (NGC 7099), the main noteworthy deep sky object in the constellation, is a globular cluster about 28,000 light years away, but approaching us at a speed of about 182 km/sec. This 12.93 billion year old cluster is about 90 light years in diameter, with its brightest components consisting of a dozen red giant stars. Messier 30 can be found just below and right of Deneb Algedi, although you’ll need a telescope or binoculars to study this Messier object because of its 7.5 magnitude. M30, however, is one of the easier globular clusters to spot, and can be found low in the SSE sky.

Other deep space objects of interest in this constellation include the elliptical galaxy NGC 7103, and the spiral galaxy NGC 6907.

Meteor Showers: 5

The Sea Goat Capricornus is home to 5 meteor showers, including;

– The Alpha Capricornids usually runs from July 15th to about September 11th, with the peak usually occurring around August 1st when 6 to 14 meteors per hour can be seen. This shower is known for having really bright meteors and occasional fireballs. Lasting almost a month you get plenty of time to take a peek.

– The Chi Capricornids run from Jan 29th to Feb 28th, and peak on Feb 13th. This meteor shower is associated with the asteroid Adonis, but it occurs during the daytime and so is only detectable by radio observations.

– The Sigma Capricornids is active from about June 18th to July 30th, with the peak expected to occur on June 27th. However, it is a very light shower that produces around 2 meteors per hour, and therefore is often missed, especially with the volume of other showers taking place in this part of the sky at this time of year.

– The Tau Capricornids is regarded as a minor shower that runs from June 16th to July 29th, with a peak on July 12th. However, meteors from this shower are best observed telescopically, which might make tracking individual meteors difficult.

– The Capricorniden-Sagittarids shower takes place on Feb 1st, but is a daytime shower, so unless you own a radar set you won’t be watching this one.

Planets: 9+ Known

All told, there are 5 stars in the constellation that host 9 planets between them, with one planet having a potentially habitable moon.

Astrology: Dec 22 to Jan 19

In astrology, the Sun enters Capricornus on 21st/22nd December, marking the beginning of the winter solstice and the shortest day in the northern hemisphere. These dates, however, hark back to the early Bronze Age, and due to precession over time the winter solstice is now actually marked by the Sun entering Sagittarius on this date. These days the Sun actually passes in front of the constellation Capricornus from around January 20th to February 16th, a full month later. Other astrological associations include the following:

Date of Birth: Dec 22 to Jan 19
Sign Ruler: Saturn
Element: Earth
Birth Stone: Agate, Garnet, Vesuvianite
Metal: Lead
Color: Brown, black, dark green
Characteristics: Intelligent, practical, reliable, generous, optimistic, persistent
Compatibility: Virgo, Taurus and Pisces

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