Jimmy Westlake: A river of stars
February 6, 2012
Steamboat Springs — The very familiar star pattern of Orion the Hunter is found overhead at 8 p.m. in early February. The bright stars Betelgeuse and Rigel at his shoulder and foot, respectively, join the three stars in a row marking Orion's Belt to form one of the most widely recognized star patterns in the entire sky.
But it's a little star just above Rigel to which I would like to draw your attention. Despite its proximity to Rigel, this little star does not belong to the constellation Orion, but falls in the neighboring constellation of Eridanus the River. The star is named Cursa, which means the "foot stool," because Orion seems to be stepping on it with his big foot, Rigel.
Cursa is the first bright star in a long, meandering stream of stars that represents the Po River in Italy. The river was immortalized in the stars to console Helios, the mythological sun god of the Greeks, after his son Phaethon drove his fiery chariot too close to the Earth and caught it on fire. Zeus, the king of the Greek gods, had to shoot down the lad and his runaway chariot with a lightening bolt to spare the Earth. Phaethon's body fell like a meteor into the Po River, where his sisters wept tears that turned into drops of amber.
Eridanus is the sixth largest constellation in our sky. To locate the celestial river, start with the star Cursa near Orion's foot and connect the dots toward the right, or west, tracing out an enormous backward letter 'S.' These meandering curves in the river are as large as Orion but composed of fainter stars. Eridanus then flows straight down below the southern horizon and out of our view.
Folks living below the latitude of 32 degrees north get to see the bright star Achernar that marks the pool at the end of the river. That's roughly the latitude of Savannah, Ga., Midland, Texas, and San Diego. The entire state of Colorado is too far north to get a glimpse of Achernar, the sky's 10th brightest star.
The unassuming little star Epsilon Eridani is an interesting star for a couple of reasons. It is the closest solar analog, or twin of the sun, to our solar system and as such has been used in science fiction stories as a home for extraterrestrial beings. It is known to possess at least two planets of its own. However, planets orbiting Epsilon Eridani probably would not host intelligent life forms, in spite of what science fiction authors might have us believe. The star system is relatively young — only half a billion years old — compared to 4.6 billion years old for Earth.
Jimmy Westlake teaches astronomy and physics at Colorado Mountain College's Alpine Campus. Check out Jimmy's astrophotography website at http://www.jwestlake.com.