Sky watch: Trace the faint river trail of Eridanus

You can stand outside every night of the year and you won't see a sky more brilliant than that of winter. Most remarkable is that during the early evening hours right now, you can find three-quarters of the 50 most brilliant stars in the entire sky. Too bad so much of the country is in a deep freeze and that most people don't venture out to explore the amazing nighttime sights.

Those who love the sky, however, are a different lot. When stargazers peer skyward at dusk on cold February evenings, they find it hard to ignore Orion, the hunter, standing stoically over the southern horizon. Even those who just "accidentally" glance upward as they race from their cars to their nice warm homes almost instantly notice the four bright stars that outline a rectangle and three more that trace a straight line in its center.

While Orion unquestionably represents our winter's most attention-grabbing star grouping, it's not the only constellation in that area of the sky. In fact, one of the longest of all constellations begins near the foot of the great hunter. Its name is Eridanus, the river.

Finding this string of relatively faint stars isn't difficult. First, locate the southwestern-most star of Orion (Rigel). Next, look just above and to its right for the fainter star that marks the "head" of the river. If you've got a dark night with no moonlight and a fairly low southern horizon, you should be able to trace much of the river as it meanders west and south.

Because Eridanus lies so far south, stargazers in the Earth's Northern Hemisphere can see only a portion of it. If you live in middle or high latitudes, you might see one-third or half of it. Those living in more southerly locations will see nearly all. Only those near or south of the equator can see the entire constellation, as it meanders almost all the way to the south celestial pole.

In Greek mythology, Eridanus is the river in which young Phaethon crashed after his failed attempt to fly the chariot of the sun, but no one knows exactly which river Eridanus was supposed to represent. Some claim it's the Tigris or the Euphrates; others suggest it might be the river Po or possibly even the mighty Nile.