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Rare exoplanet 39 EP

HD 218566 b

RA 347.2974° · Dec -2.2612° · exoplanet

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Score breakdown

· 3 badges
39 pts · Rare
Rare 50 pts → Epic
  • In the habitable zone +30
  • Confirmed exoplanet +5
  • Gas giant +4
Total score 39

11 more points to reach Epic.

Badges

  • Confirmed exoplanet · +5
  • In the habitable zone · +30
  • Gas giant · +4

Trivia

What makes it special

  • Goldilocks zone. Sits where it's neither too hot nor too cold — liquid water could exist on a surface here.

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

  • 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.
  • What the zone means. The habitable zone is only about temperature: it is the band where liquid water could survive on a surface. It is a promising address, not evidence of anything living.

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 8.6 it is just past naked-eye reach — ordinary binoculars will pull it in.
  • Seen from everywhere. It sits almost on the celestial equator, so it can be seen from essentially anywhere on Earth.
  • Best time of year. It stands highest in the middle of the night around September — that's when to go looking.

Properties

density gcc
0.431
diameter km
118887.784
discovery facility
W. M. Keck Observatory
discovery method
Radial Velocity
discovery year
2010
dist ly
94.0223
eccentricity
0.3
eq temp k
253.15
habitable zone
yes
host star teff
4730
insolation
0.7414
mag
8.6
mass earth
63.566
name
HD 218566 b
orbital period days
225.7
radius earth
9.32
semi major au
0.69
spect
K3V
sys num planets
1
sys num stars
1

Nearby objects

About HD 218566 b

HD 218566 b is a rare exoplanet. It lies about 94 light-years from Earth, shines at apparent magnitude 8.6, has spectral type K3V and has an equilibrium temperature near 253 K.

Sits where it's neither too hot nor too cold — liquid water could exist on a surface here.

How to see it

At apparent magnitude 8.6, it is an easy target for binoculars.

Like any astronomical target, HD 218566 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 218566 b is a rare exoplanet

HD 218566 b scores 39 points on Spacedle's rarity scale, which places it in the rare tier. Another 11 points would lift it into a rarer tier.

That score comes from 3 science badges — Confirmed exoplanet, In the habitable zone and Gas giant — 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.