Epsilon Eridani (Ran)
Epsilon Eridani (Ran) is a star in the constellation Eridanus, magnitude 3.7.
A young, restless Sun-like star next door, with a giant planet, dust belts and Norse sea gods for names.
Young stars are restless, and Epsilon Eridani is no exception. About a billion years old, it is smaller and cooler than the Sun — an orange K-type star — but its magnetic activity is higher and its stellar wind about 30 times as strong. It spins once every 11.2 days at its equator.
It has a family. A giant planet, Epsilon Eridani b, circles it — first announced in 2000 and long debated, but now accepted by most astronomers. Farther out lie a belt of warm dust and a cold ring like our Kuiper belt, with a gap between them that hints at more unseen planets. As one of our nearest Sun-like neighbours it has been a target in the search for alien radio signals since Frank Drake’s Project Ozma in 1960, and a favourite of science fiction.
In 2015 the star and planet were named Ran and AEgir, after the Norse sea goddess Rán and her husband Ægir, god of the ocean. The names were proposed by eighth-grade pupils at Mountainside Middle School in Colbert, Washington.
Epsilon Eridani (Ran) is 10.5 light-years away: the light we see from it set off in 2016, 5 years before the James Webb Space Telescope was launched.
Did you know?
- Our Sun, seen from there. Seen from Epsilon Eridani, the Sun would be a 2.4-magnitude star in the constellation Serpens.
- Ptolemy’s leading star. Ptolemy listed it in his Almagest as the star that leads a group of four in the River — the first of them to cross the sky each night.
- A family resemblance. Epsilon Eridani may belong to the Ursa Major moving group, stars that share a path through the galaxy — and perhaps a birth in the same cluster.
An orange-tinted 4th-magnitude star in the northern part of Eridanus, about two and a half degrees west of Delta Eridani. Binoculars bring out its warm colour — the light of one of the nearest Sun-like stars.
When and where to see it
It is best placed in the evening sky around December, when it crosses the meridian at about 10 pm local time (around midnight in November). It can be seen from everywhere south of 81°N and never sets south of 81°S.
At its highest it stands 31° up from 50°N, 46° up from 35°N, 81° up from the equator, 64° up from 35°S.
Facts
- Type
- Star
- Constellation
- Eridanus
- Designations
- Ran, ε Eri, 18 Eri, HR 1084, HD 22049, HIP 16537
- Magnitude
- 3.7
- Position
- RA 3h 32.9m, Dec −9° 27′ (J2000)
- Spectral type
- K2V
- Colour
- orange (B−V 0.88)
- Distance
- 10.5 light-years
- Discovered
- Known since antiquity
Open AstroPilot to see when Epsilon Eridani (Ran) is highest tonight from your location, how easy it is with your telescope or binoculars, and an eyepiece view.