Eridanus

When and where to look for Eridanus

Eridanus crosses the meridian — its highest point in the sky — at local midnight around November, which makes the months from October to December the easiest time to find it in the evening. It spans declinations -57.2° to -3.3°, so visible from everywhere south of about 33°N.

The quickest way to find it is to open the live AR sky map and point your phone at the sky — if Eridanus is above your horizon right now, its figure is drawn in the position it genuinely occupies above you.

Brightest stars in Eridanus

Magnitude runs backwards: lower numbers are brighter, and anything below about 6.5 is beyond the naked eye under a dark sky.

What Eridanus is made of

The catalogue lists 195 stars within Eridanus, of which 195 are magnitude 6.5 or brighter — the limit of what an unaided eye picks up under a genuinely dark sky. The rest need binoculars or a telescope.

Spectral make-up

Spectral class is a temperature ordering, running from O at around 30,000 K down to M below 3,500 K. A constellation is a direction, not a group, so this is simply what happens to lie along that line of sight.

The closest catalogued star in this direction is Ran at 10.5 light years. The most distant is 55 Eri at roughly 2,132 light years — stars that appear side by side here are nothing of the sort.