Sea of Constellations Visible For Northern Hemisphere Skywatchers

Sea of Constellations Visible For Northern Hemisphere Skywatchers
This sky map depicts the many sea-oriented constellations visible during autumn in the northern hemisphere in 2010. (Image credit: Starry Night [Full Story)

The traditionalconstellations of autumn in the Northern Hemisphere have returned to theevening sky and bring with them a rich body of lore and mythology ? thoughtheir stars are rather faint.

Several of theseconstellations are dwelling in the celestial "sea" ? that is, they are of a watery nature. 

These constellations includeCapricornus, the sea goat; Aquarius, the watercarrier; Pisces, the fishes; Piscis Austrinus, the southern fish; Cetus,the sea monster; and Eridanus, the river. They areappearing this week in the southern part of the evening sky at around 8 p.m.local time in northern latitudes.

Thissky map shows the constellations of the southern sky in the NorthernHemisphere this week.

The first threeconstellations mentioned here form part of the zodiac;w all members of this group have been associatedwith the rainy season of ancient Mideast lands.

 There is also amythological connection between these star pictures and an ancient great floodin the Tigris-Euphrates basin, which has sometimes been linked to the Deluge inGenesis. Here's a tour of these water-themed constellations in the night sky:

Grotesque sea goat

Probably because the ancients knew very little aboutmarine life, it is not surprising that they populated the deep with everymanner of monster, including what we now call mermaids.  Capricornus, the sea goat, now leaning down in thesouthwest sky, is one of those odd land-sea animal hybrids the ancients werewont to create. 

It traces back to the Mesopotamian period. According tofolklore, there were some sea nymphs and goddesses playing in a field one daywhen the mischievous god, Pan, saw them and joined in the fun.  In orderto amuse them, he transformed himself into a goat and leaped into theriver.  Instantly, the part of his body that was submerged in the waterwas turned into a fish while the part out of the water remained a goat. 

Zeus, who just happened to be passing by, saw Pan?s featand was so amused that he decreed the perpetuation of this grotesque figure inour night sky. Although Capricornus is a goat, in thesky it looks more like a roughly triangular figure which may suggest aninverted cocked hat, perhaps a bird flying toward you, or even a boat. 

Once, I pointed it out to a friend of mine who remarkedthat (in keeping with the watery aspect) it looked "like the south end ofa bikini."

Watery tale

The rich mythology of Aquarius, the water carrier, whichhovers above and to the left of Capricornus, is veryancient, tracing back to the earliest civilizations in the Tigris and Euphratesvalleys. 

In fact, on some of their cylinder seals they picturedthese rivers as pouring out from Aquarius? water jar. The ancient Egyptians hadan equally picturesque image of this constellation that they associated withthe Nile?sannual flooding, which, far from being disastrous, added a new layer eachyear to the valley?s fertile soil. 

The Egyptians believed the flooding was caused byAquarius dipping his water jar into the river to refill it. Quite a number ofAquarius' stars have proper names. The names Sadalmelik,Sadalsuud[s1] , Sadachbia, and Albali allindicate in Arabic that these are "lucky" stars astrologically."Skat" means the lower foot in Arabic,while "ancha" comes from Medieval Latin andrefers to the upper thigh or hip.

One fish, two fish

Were it not one of the 12zodiacal signs, Pisces the fishes would not be deemed important at all.  

Astronomers measure starbrightness in terms of magnitude ? the smaller the number (close to or lessthan one), the brighter the object. None of the stars in Pisces shine brighterthan fourth magnitude ? though brilliant Jupiter currently resides here ? butthe constellation does display a striking, though not bright, pattern now highin the southern sky.

It also has some historicalaffinities, including one related to Christmas. 

To the early Israelites,Pisces was a sacred part of the sky. Planetary gatherings or other occurrencesof astrological significance were regarded as harbingers of important events ifthey happened there. 

For example, a favorite explanationof the Star of Bethlehem is a planetary grouping involving Mars, Jupiterand Saturn that took place in Pisces in 6 B.C.

The main legend to accountfor the Fishes is that Cupid and Venus ? the god and goddess of love ? escapethe monster Typhon by jumping into a river andassuming a piscine form.

Long-necked bird and a southern fish

In addition to the six groupings I mentioned earlier, wemight also include the constellation of Grus, theCrane, among the watery constellations, for this wading bird often inhabitsswampy and marshy terrain.

It currently lies low near the southwest horizon. Withits two second-magnitude stars marking the bottom of a distinctive invertedY-shaped pattern, and with third-magnitude Gamma at the top, Grus is actually a prominent fall constellation for viewersin the tropics and the Southern Hemisphere. 

Directly above Grus is Piscis Austrinus, the southernfish, which has the only first- magnitude star ? Fomalhaut? in this whole collection of watery constellations.

Aside from Jupiter ? which this year happens to beglowing brilliantly nearby in Pisces ? Fomalhautusually appears as a solitary star in a very dull and unexciting region of thesky. 

Indeed, Fomalhaut is the only"true" first magnitude star of autumn. It's a white star, only abouttwice as large as the sun and about 14 times as bright. It appears prominent tous because it is only 25 light-years away.


East of Aquarius and south of Pisces is Cetus, a sea monster who in mythology was sent by the godNeptune to devour the princess Andromeda. 

This constellation is oftencalled the Whale, but in the allegorical pictures found in many of the oldstar atlases it usually appears very un-whale-like (almost like Godzilla with afish tail!). 

However, today we identify the scientific name for thewhale order is Cetacea, and the study of whales isknown as Cetacean Zoology; hence the name Cetusidentifies this constellation as a whale.

Lazy celestial river

Lastly, now coming into view low in the southeast is alarge, albeit faint and shapeless constellation known as the Celestial River, Eridanus.

It starts near the brilliant bluish-white star Rigel in Orion then flows southwestward just like a riverwould: a winding stream of dim stars whose meanderings wind all the way down tobelow the southern horizon. Unfortunately, stargazers in much of the UnitedStates never get to see the very end of the river, for it ends in a blaze ofsplendor. 

The bluish star Achernar glowsat the end of the river, ninth-brightest star in the sky, yet so far south thatonly those who live near and along the Gulf Coast (Florida, New Orleans, southTexas), get a glimpse of it, poking a short distance above the horizon.

 Also in Eridanus isEpsilon Eridani, the third-nearest star visible tothe unaided eye.

Located at a distance of just 10.8 light years fromEarth, Epsilon has about one-third of the luminosity of our sun and is about 90percent as large. Thus, here is a star that is reasonably comparable to our ownsun.

Joe Rao serves as aninstructor and guest lecturer at New York's Hayden Planetarium. He writes aboutastronomy for The New York Times and other publications, and he is also anon-camera meteorologist for News 12 Westchester, New York.

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Joe Rao
Skywatching Columnist

Joe Rao is's skywatching columnist, as well as a veteran meteorologist and eclipse chaser who also serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for Natural History magazine, the Farmers' Almanac and other publications. Joe is an 8-time Emmy-nominated meteorologist who served the Putnam Valley region of New York for over 21 years. You can find him on Twitter and YouTube tracking lunar and solar eclipses, meteor showers and more. To find out Joe's latest project, visit him on Twitter.