Eridanus is one of the most extensive constellations, however most of its stars are fairly faint and half the constellation extends below -30º, which means much of North America and Europe cannot see many of its stars. On the other hand, if you live in Central America or equivalent latitude you'll be able to enjoy the entire journey. It's quite an adventure to set out at the river's source, lambda Eridani, next to Rigel, and to follow its course through the twists and turns, as far as you can until (probably) it disappears over the horizon at some point. I encourage you to follow each stop along the way. You'll be amazed at how easily you can follow the river's progress, even with the naked eye. So get ready to set out on that adventure -- starting at beta Eridani (upper lefthand corner).
Beta Eridani is called "Cursa", meaning 'the footstool' because it is found at the foot of Orion. Beta Eridani is a blue-white star 89 light years away with a visual mag of 2.78, the brightest star of the constellation for many viewers since Achenar, alpha Eridani (a very bright 0.45) isn't visible north of Florida or Texas. As is the case with many a great river, it begins undramatically with the 4th-mag lambda Eridani. It flows north to beta then turns west to omega Eridani.
Epsilon Eridani is west of delta, in the same FOV. It's quite an interesting star. The star, only 10.5 light years away, is quite similar to our sun. If you move epsilon slightly to the left (east) of centre, you'll find that zeta Eridani has moved into view on the right edge. Now if you move this star to the left of your FOV, eta will appear on the far right. Three dimmer stars are in the middle of your FOV, above centre. These are rho 1, 2, and 3 and they are not part of the river.
Eta Eridani serves as the end of the first western branch of the river. From here the Eridanus makes a steep descent to the 'tee' stars. In fact we'll need some help from neighbouring Cetus. If you put eta Eridani at the top of your FOV, you'll see a bright star near the lower right edge. This is pi Ceti. Now put pi Ceti at the top of your glasses and you'll find tau-1 in the middle of your FOV a bit below centre. We are now at the lettered stars. "g Eridani" is the brightest of this group at 4.2, and "f" appears to be next brightest because of its combined visual mag of 4.3. In reality "f Eri" is a pleasant double star that goes by the name of DUNS 16 (4.8, 5.4. PA 212º and separation 8"). Now if you put y Eridani at the upper left corner of your glasses, the brightest star in your FOV, just southwest of centre, is "e Eridani". We are now quite far south, at -43º declination. If you've been able to voyage all the way down to these 'lettered' stars, you aren't that far from completing the voyage.
With xi Eridani at the upper left of your FOV you should see the two omicron Eridani stars just off centre. They resemble a faint version of Castor and Pollux (being of 4.0 and 4.5 visual mag). In reality, the omicron stars are not associated with each other -- omicron1 is 125 light years away while omicron2 is a very close 16.4 light years. Before passing through the 'narrows' here, you might pause briefly and study omicron2. The star, also known as 40 Eridani, is the primary of a triple system. Its 9th-mag companion, a white dwarf, may not be visible in binoculars, but it is easily seen in medium sized telescopes. If your scope is large enough, you'll also find an 11th-mag red dwarf gravitationally attracted to the white dwarf, making it one of the more compelling trios in the heavens. Now -- with the naked eye or binoculars -- look to the southwest of the twin omicrons and you'll find gamma, Zaurak, a rather reddish star which also has a faint companion. From Zaurak you climb once more, up to delta. I consider kappa a kind of 'cataract' -- that is, a waterfall that bounces off some outcrop (kappa) on its way farther down the cliff to phi. Kappa, phi, and chi are all in the same FOV. Once the river reaches phi I imagine it to form a vast lake, on the other side of which is chi, on the western edge. Now, just below chi -- about seven degrees -- is the brightest star of the constellation, the unmistakeable Achernar, and so to the mouth of the river and our voyage is over. If you wish some help to remember the many stops along the way, this memory aid may help.
Mu Eridani is the point the farthest north on the river. In binoculars you'll see a trio of stars making a 'roof'. From here proceed to xi. You've presumably been able to star-hop down from eta Eridani, using pi Ceti as a mid-point helper. Now place tau-1 just outside the top right corner of your glasses and you'll have both tau-2 and tau-3 in view. With tau-3 at the right edge you can see tau-4 northeast (a bright star, 15 Eri, is just below it). Put tau-4 just outside the upper right corner and you'll have tau-5, tau-6, and tau-7. You'll see that tau-6, tau-7, tau-8, and tau-9 make a tightly-formed half-crescent. Having proceeded from 'f' Eridani to 'e', now place this star at your lower left corner of your binocular FOV. You'll find the much brighter theta Eridani on the upper right corner. Theta Eridani now carries the name Acamar, a variation on Achernar (End of the River) since it was once the terminus. Theta is a pleasant binary of two bright stars (3.3, 4.4) with a positioin angle of 88º and separation of 8.2", visible in medium-sized telescopes. Now place theta on the upper left of your FOV. You'll see two stars to the west, one over the other. These are iota and 's Eridani'. From iota the river descends straight south to 's' then further south (about seven degrees) to kappa. I see it as a multiple falls, bouncing from 's' to kappa and continuing further down... We've nearly made it the full length of the river. There aren't many stars here to guide the way. With tau-9 at the extreme right edge, move the binoculars one FOV due east and one field due south. You should see two stars, one below the other and just to the east. These are upsilon-1 and upsilon-2. Move south slightly and you have all the upsilon stars. And so it's on to some oddly labelled stars: 'g', 'f', 'y', and 'e'. Place upsilon-4 on your left edge and you'll see two, perhaps three stars, at the extreme right edge. The upper star is "i", which is not part of the river group. Move the glasses south until "i" leaves the group; another has moved into the bottom of your FOV. This is "y".
From this star, xi Eridani, the river begins the first of its many descents, rushing toward the two omicrons. I think of the river as passing through the 'narrows' here, and plunging wildly even more southward, to Zaurak, gamma Eridani. Some cartographers omit this stop at xi, instead having the river immediately flow toward the omicrons after nu. Their reason perhaps is that xi Eridani is much fainter, a 5.2 visual magnitude star, thus shouldn't be included. It's true that xi Eridani is the faintest of all the stars I include along the way, but by using this star it's easier to starhop to the next stop along the way -- which is to the two stars omicron, to the southwest.
