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Epic exoplanet 71 EP

51 Peg b

RA 344.3675° · Dec 20.7691° · exoplanet

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Score breakdown

· 7 badges
71 pts · Epic
Epic 78 pts → Anomaly
  • Found before the year 2000 +18
  • Lava world +14
  • Its star is visible to the naked eye +12
  • Tidally locked +10
  • Orbits a Sun-like star +8
  • Confirmed exoplanet +5
  • Gas giant +4
Total score 71

7 more points to reach Anomaly.

Badges

  • Confirmed exoplanet · +5
  • Gas giant · +4
  • Lava world · +14
  • Tidally locked · +10
  • Its star is visible to the naked eye · +12
  • Orbits a Sun-like star · +8
  • Found before the year 2000 · +18

Trivia

What makes it special

  • Lava world. Its surface is almost certainly an ocean of molten rock, kept liquid by the star it hugs.

Hard to believe

  • It would float. It is less dense than water. Drop it in a big enough ocean and the whole world would bob on the surface.

What it actually is

  • Hugging its star. It orbits closer to its star than Mercury does to the Sun, completing a lap in less time than Mercury takes.
  • What it is made of. Lighter than Neptune — a puffed-up ball of hydrogen and helium with no surface anywhere on it to stand on.

Sense of scale

  • In perspective. Inside our stellar backyard: every radio broadcast humanity has ever made has already swept past it.

Find it in the sky

  • How to spot it. At magnitude 5.5 you can see it with your own eyes from a dark site.
  • Northern sky. It rides the northern half of the sky — an easier target the further north you are.
  • Best time of year. It stands highest in the middle of the night around September — that's when to go looking.

Properties

density gcc
0.38
diameter km
179862.42
discovery facility
Haute-Provence Observatory
discovery method
Radial Velocity
discovery year
1995
dist ly
50.4283
eccentricity
0.0063
eq temp k
1328.93
host star teff
5761
inclination
49.8
insolation
506.1775
mag
5.4531
mass earth
193.8753
name
51 Peg b
orbital period days
4.2308
radius earth
14.1
semi major au
0.052
spect
G5V
sys num planets
1
sys num stars
1
tidally locked
yes
tidally locked inferred
yes

About 51 Peg b

51 Peg b is an epic exoplanet. It lies about 50.4 light-years from Earth, shines at apparent magnitude 5.45, has spectral type G5V and has an equilibrium temperature near 1,329 K.

Its surface is almost certainly an ocean of molten rock, kept liquid by the star it hugs.

How to see it

At apparent magnitude 5.45, it can be glimpsed with the unaided eye under dark skies.

Like any astronomical target, 51 Peg 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 51 Peg b is an epic exoplanet

51 Peg b scores 71 points on Spacedle's rarity scale, which places it in the epic tier. Another 7 points would lift it into a rarer tier.

That score comes from 7 science badges — Confirmed exoplanet, Gas giant, Lava world, Tidally locked, Its star is visible to the naked eye, Orbits a Sun-like star and Found before the year 2000 — 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.