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Rare exoplanet 47 EP

HD 221585 b

RA 353.2294° · Dec 63.1556° · exoplanet

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Score breakdown

· 4 badges
47 pts · Rare
Rare 50 pts → Epic
  • In the habitable zone +30
  • Orbits a Sun-like star +8
  • Confirmed exoplanet +5
  • Gas giant +4
Total score 47

3 more points to reach Epic.

Badges

  • Confirmed exoplanet · +5
  • In the habitable zone · +30
  • Gas giant · +4
  • Orbits a Sun-like star · +8

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.

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. 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 7.5 it is just past naked-eye reach — ordinary binoculars will pull it in.
  • Never sets. So far north that from Britain, Canada or northern Europe it never dips below the horizon — it is up every clear night of the year.
  • Best time of year. It stands highest in the middle of the night around September — that's when to go looking.

Could we get there?

  • Verdict. Hopelessly far for any craft humanity can build today.

Properties

density gcc
1.14
diameter km
172208.7
discovery facility
Haute-Provence Observatory
discovery method
Radial Velocity
discovery year
2016
dist ly
182.1695
eccentricity
0.123
eq temp k
242.77
habitable zone
yes
host star teff
5620
insolation
0.4965
mag
7.457
mass earth
511.7063
name
HD 221585 b
orbital period days
1173
radius earth
13.5
semi major au
2.306
spect
G8 IV
sys num planets
1
sys num stars
1

About HD 221585 b

HD 221585 b is a rare exoplanet. It lies about 182.2 light-years from Earth, shines at apparent magnitude 7.46, has spectral type G8 IV and has an equilibrium temperature near 243 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 7.46, it is an easy target for binoculars.

Like any astronomical target, HD 221585 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 221585 b is a rare exoplanet

HD 221585 b scores 47 points on Spacedle's rarity scale, which places it in the rare tier. Another 3 points would lift it into a rarer tier.

That score comes from 4 science badges — Confirmed exoplanet, In the habitable zone, Gas giant and Orbits a Sun-like star — 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.