Eridanus constellation
Eridanus is one of the 88 constellations, and it represents the river. It is highest in the sky at midnight around November 16, and its whole figure rises above the horizon from 33°N to 90°S.
Eridanus at a glance
- Represents
- the river
- Highest at midnight
- November 16
- Highest at 9 pm
- December 31
- Seen whole from
- 33°N to 90°S
- Brightest star
- Achernar
- Stars in the figure
- 28 stars
- Origin
- Ptolemy's list, 2nd century
When to see Eridanus
Eridanus is highest in the sky at midnight around November 16 and at 9 pm around December 31. Each month it is highest about two hours earlier than the month before.
The times are local solar time. Clocks on summer time or daylight saving time read about one hour later.
| Date | Highest at |
|---|---|
| January 15 | 8:00 PM |
| February 15 | 6:00 PM |
| March 15 | 4:10 PM |
| April 15 | 2:10 PM |
| May 15 | 12:10 PM |
| June 15 | 10:10 AM |
| July 15 | 8:10 AM |
| August 15 | 6:10 AM |
| September 15 | 4:10 AM |
| October 15 | 2:10 AM |
| November 15 | 12:10 AM |
| December 15 | 10:00 PM |
Where to look for Eridanus
From the northern hemisphere
From 40°N, only part of Eridanus rises. Its centre is highest around midnight on November 16, 23° above the southern horizon.
From the southern hemisphere
From 35°S, Eridanus rises in the east and sets in the west. It is highest around midnight on November 16, almost overhead.
Brightest stars in Eridanus
| Star | Magnitude |
|---|---|
| Achernar | 0.45 |
Eridanus in myth and history
Eridanus is one of the 48 constellations that the astronomer Ptolemy listed in the 2nd century.
Constellations next to Eridanus
Find Eridanus in your sky
Questions about Eridanus
Eridanus is highest in the sky at midnight around November 16 and at 9 pm around December 31. The weeks around those dates are the best time to look.
The whole figure of Eridanus rises above the horizon from 33°N to 90°S, and at least part of it rises from 87°N to 90°S.
Achernar is the brightest star in Eridanus, at magnitude 0.45.
Eridanus represents the river. Eridanus is one of the 48 constellations that the astronomer Ptolemy listed in the 2nd century.