About Kepler-391 b
Kepler-391 b is an epic exoplanet. It lies about 2,835.1 light-years from Earth, has an equilibrium temperature near 930 K, spans roughly 2.5 Earth radii and weighs about 1,100 Earth masses.
Packed denser than solid iron.
Epic exoplanet 47 EP
Kepler-391 b
RA 290.6219° · Dec 51.0573° · exoplanet
Score breakdown
· 6 badgesEpic 68 pts → Anomaly
- Denser than iron +18
- Distant (>1000 ly) +10
- Multi-planet system +6
- Confirmed exoplanet +5
- Sub-Neptune +5
- Found by Kepler +3
Total score 47
21 more points to reach Anomaly.
Badges
- Confirmed exoplanet · +5
- Sub-Neptune · +5
- Denser than iron · +18
- Multi-planet system · +6
- Found by Kepler · +3
- Distant (>1000 ly) · +10
Trivia
What makes it special
- Heavyweight. Packed denser than solid iron.
Could we get there?
- Verdict. Impossible with our current technology — and the next millennium of it.
Getting there
- Aboard Voyager 1. ≈ 49.8 million years at Voyager 1's speed (17 km/s).
- Fastest probe ever. ≈ 4.4 million years even at the Parker Solar Probe's 192 km/s.
- At 10% light speed. ≈ 28.4 thousand years in a starship at a tenth of light speed.
- Distance. 2835 light-years from Earth.
Look-back time
- Look-back time. Its light left before the last ice age ended.
Saying hello
- Say hello. A radio message and its reply would take 5670 years round-trip.
Standing on it
- A year here. A full year lasts just 7.4 Earth days.
By the numbers
- Size. About 2.5× the width of Earth.
- Volume. About 15.6 Earths could fit inside it.
- Mass. Roughly 1100× Earth's mass — about 3.5 Jupiters.
- Your weight. You'd weigh about 176.0× your Earth weight standing here.
- Density. Denser than solid iron.
- Temperature. Around 657°C — hotter than a self-cleaning oven.
How we found it
- Discovery. Found by Kepler using the transit method.
Cosmic context
- Crowded system. One of at least 2 planets orbiting its star.
Properties
- density gcc
- 380
- discovery facility
- Kepler
- discovery method
- Transit
- dist ly
- 2835.0654
- eccentricity
- 0.46
- eq temp k
- 930
- insolation
- 690
- mass earth
- 1100
- name
- Kepler-391 b
- orbital period days
- 7.4175
- radius earth
- 2.5
- sys num planets
- 2
How to see it
Like any astronomical target, Kepler-391 b is best seen from a dark site away from city lights, and when it is above the horizon depends on your latitude and the time of year. The visibility panel above works out tonight's viewing window for your saved location.
Why Kepler-391 b is an epic exoplanet
Kepler-391 b scores 47 points on Spacedle's rarity scale, which places it in the epic tier. Another 21 points would lift it into a rarer tier.
That score comes from 6 science badges — Confirmed exoplanet, Sub-Neptune, Denser than iron, Multi-planet system, Found by Kepler and Distant (>1000 ly) — each earned for a real, measurable property of the object. Rarity on Spacedle is never random: the more remarkable an object's astrophysics, the more badges it collects, the higher it scores, and the rarer it ranks.