Eridanus (Pronounciation:Iri-dan-us, Abbrev:Eri, Latin:Eridani) is a constellation, one of 88 constellations that the night sky is divided into. The sky is not divided up equally between the constellations. Eridanus takes up 1137.919 sq. degrees of the night sky which equates to 2.76% of the night sky. The constellation gets its name as it name means River Eridanus . The constellation is one of the original constellations that was devised by the Ancient Greco-Egyptian astronomer Ptolemy who lived between 90 A.D. and 168 A.D.
Eridanus is not a member of the Zodiac group of twelve constellations that appear when the Sun sets. Eridanus is a southern hemispheric constellation which means it can't be seen easily or at all from the northern hemisphere.
The brightest star in Eridanus is Achernar. There are 32 Extrasolar Planets (Exoplanets) in this constellation that are detailed on this site. There is a dedicated page for exoplanets in Eridanus. For a list of named stars, that is stars that don't start HD or HIP, please visit Eridanus Star List Page.
The number of stars that have been catalogued as part of the Hipparcos Star Catalogue from Eridanus is 2759. The number of stars that are of magnitude 6.0 or lower in the constellation is 128. The number of stars in the constellation that make up the outline is 35.
There are no deep space objects that were identified by Charles Messier in this constellation. There are 2 non-Messier deep space objects that are covered on this site and the list is below.
The nearest star to Earth is Ran which is roughly about 10.49 Light Years from the Earth. The nearest star to the Earth with an exoplanet is Sadira which is about 10.49 Light Years. The furthest star that can be located in the constellation is HIP 13391 which is located about 326163.3 Light Years away from the Sun. The furthest figure is derived from either the 1997 or 2007 Hipparcos star catalogue parallax figure and it has been known to produce distances that are wrong.
The dimmest star that can be seen in Eridanus with the naked eye is GZ Eridani. The dim star has an apparent magnitude of 6. The dimmest star that a person is able to see with their naked eye is 6.0 magnitude based on the table in the reference. Ref: University of Michigan
The caveat of these stars are that they are catalogued on this site. If you know of a star that is nearer or further then do let me know in the comments and I'll add it to the site. The stars mentioned are from the Hipparcos catalogue or have been added because of their special status.
Eridanus, the river was where Phaethon fell into when he was knocked out of his chariot basket. Phaethon had taken his father Helios' chariot and rode it across the skies both too high and too lower. As it was scaring the people below, Zeus threw fire bolts at the chariot to stop him. The chariot stopped but Phaethon fell out and into the river.
There are 14 Meteor Showers that occur during the year within this constellation based on information gathered from Adam Mickiewicz University (Poland). The ones listed as the ones I've been able to find a date range for. For others if you have the time, you can visit the AMU site, obtains the SL value then use IMO tables to calculate the date. A lot of the Meteor Showers are weak and you need to do a lot of stargazing to spot them.
| Name | Activity | Peak Activity | Closest Star |
| Eta Eridanids | 3 Aug- 14 Aug | 09-Aug | Azha |
| Name | Eridanus |
| Abbreviation | Eri |
| Is a Zodiac Sign | No |
| Brightest Star | Achernar |
| Area | 1137.919 sq. deg. |
| Percentage of Night Sky | 2.76% |
| Size Position | 6th |
| Hemisphere | Southern |
| Site Exoplanet Count | 32 |
| Meteor Shower Count | 14 |
| Nearest Star | Ran |
| Nearest Star with Exoplanet(s) | Sadira |
| Dimmest Star | GZ Eridani |
| Furthest Star | HIP 13391 |
| Bright Star Count | 128 |
| Hipparcos Star Count | 2759 |
| Main Star Count | 35 |
| Messier Deep Space Object Count | 0 |
| *Non-Messier Deep Space Object Count | 2 |
| Bordering / Neighbouring / Surrounding Constellations | Taurus |
| Cetus | |
| Fornax | |
| Phoenix | |
| Tucana | |
| Horologium | |
| Caelum | |
| Lepus | |
| Orion | |
*Note: The number of Non-Messier Deep Space Object Count relates to how many are covered on this site not how many there are.
The map was generated using Night Vision, an awesome free application by Brian Simpson.
| Name | Type | Distance | Declination | Right Ascension |
|---|---|---|---|---|
| NGC 1300 | Barred Spiral Galaxy | 61 | -19:24.41 | 13h 19m 41s |
The Eta Eridanids has a very low zenith hourly rate so don`t expect anything spectacular like you might see with the Geminids or Perseids. The latter of the two occurs at roughly the same time. They are quite swift at a speed of about 65km/s. Although possible of up to 6 per hour, its more likely that its only one. Ref: IMO
Although attributed to the Chacornac comet, it could also be attributed to Comet Pons-Gambart but the former is more likely to be the source. It is a relatively newly discovered meteor shower compared to other meteor shower. Pons-Gambart return has only be recorded in 1827, it is considered to be a lost comet. Chacornac is a long time period comet whereas Pons-Gambart is about 65 years. Ref: Harvard
| Associated Comet | C/1852 K1 (Chacornac)? |
| Max Activity Date | 09 Aug |
| Activity Period | 3 Aug- 14 Aug |
| Right Ascension | 43.7 |
| Declination | -11.9 |
| Solar Longitude | 137 |
| Alpha Radiant | 43.7 |
| Speed | 65 |
| Zenith Hourly Rate | 6 |