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Epic exoplanet 57 EP

HD 20781 b

RA 50.0140° · Dec -28.7841° · exoplanet

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Score breakdown

· 5 badges
57 pts · Epic
Epic 78 pts → Anomaly
  • Earth-sized +16
  • Richly packed system +14
  • Two suns in its sky +12
  • Tidally locked +10
  • Confirmed exoplanet +5
Total score 57

21 more points to reach Anomaly.

Badges

  • Confirmed exoplanet · +5
  • Earth-sized · +16
  • Tidally locked · +10
  • Richly packed system · +14
  • Two suns in its sky · +12

Trivia

What makes it special

  • Earth-sized. Genuinely comparable to Earth in size. Worlds in this narrow band are the ones every next-generation telescope is being pointed at.

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. Denser than Earth — a solid world of rock and iron, with no meaningful atmosphere to speak of by mass.
  • Crowded system. One of at least 5 planets orbiting its star.

Sense of scale

  • In perspective. Far away by human standards, yet still a local address inside the Milky Way's spiral arms.

Find it in the sky

  • How to spot it. At magnitude 8.5 it is just past naked-eye reach — ordinary binoculars will pull it in.
  • Southern sky. It rides the southern half of the sky — an easier target the further south you are.
  • Best time of year. It stands highest in the middle of the night around November — that's when to go looking.

Properties

density gcc
5.99
diameter km
15435.002
discovery facility
La Silla Observatory
discovery method
Radial Velocity
discovery year
2019
dist ly
117.3232
eccentricity
0.1
eq temp k
1006.1
host star teff
5256
insolation
175.0994
mag
8.48
mass earth
1.93
multi star system
yes
name
HD 20781 b
orbital period days
5.3135
radius earth
1.21
semi major au
0.0529
spect
K0 V
sys num planets
5
sys num stars
2
tidally locked
yes
tidally locked inferred
yes

About HD 20781 b

HD 20781 b is an epic exoplanet. It lies about 117.3 light-years from Earth, shines at apparent magnitude 8.48, has spectral type K0 V and has an equilibrium temperature near 1,006 K.

Genuinely comparable to Earth in size. Worlds in this narrow band are the ones every next-generation telescope is being pointed at.

How to see it

At apparent magnitude 8.48, it is an easy target for binoculars.

Like any astronomical target, HD 20781 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 HD 20781 b is an epic exoplanet

HD 20781 b scores 57 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 5 science badges — Confirmed exoplanet, Earth-sized, Tidally locked, Richly packed system and Two suns in its sky — 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.