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Rare exoplanet 47 EP

HD 221420 b

RA 353.3319° · Dec -77.3853° · exoplanet

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Score breakdown

· 6 badges
47 pts · Rare
Rare 50 pts → Epic
  • Its star is visible to the naked eye +12
  • Long-period world +10
  • Frozen world +8
  • 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
  • Gas giant · +4
  • Frozen world · +8
  • Long-period world · +10
  • Its star is visible to the naked eye · +12
  • Orbits a Sun-like star · +8

Trivia

What makes it special

  • Frozen world. A deep-frozen world, too far from its star's warmth for anything to stay liquid.

Hard to believe

  • Denser than iron. It is packed tighter than solid iron — whatever it is made of, it is not ordinary rock.

What it actually is

  • What it is made of. Denser than Earth — a solid world of rock and iron, with no meaningful atmosphere to speak of by mass.

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 5.8 you can see it with your own eyes from a dark site.
  • Southern sky only. So far south it never rises for most of the northern hemisphere. To see it you'd have to travel to Chile, South Africa or Australia.
  • 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
23.1
diameter km
153074.4
discovery facility
Anglo-Australian Telescope
discovery method
Radial Velocity
discovery year
2019
dist ly
101.5699
eccentricity
0.14
eq temp k
123.49
host star teff
5847
inclination
164
insolation
0.0389
mag
5.82
mass earth
7278.2705
name
HD 221420 b
orbital period days
10090
radius earth
12
semi major au
10.15
spect
G2 IV-V
sys num planets
1
sys num stars
1

About HD 221420 b

HD 221420 b is a rare exoplanet. It lies about 101.6 light-years from Earth, shines at apparent magnitude 5.82, has spectral type G2 IV-V and has an equilibrium temperature near 123 K.

A deep-frozen world, too far from its star's warmth for anything to stay liquid.

How to see it

At apparent magnitude 5.82, it can be glimpsed with the unaided eye under dark skies.

Like any astronomical target, HD 221420 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 221420 b is a rare exoplanet

HD 221420 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 6 science badges — Confirmed exoplanet, Gas giant, Frozen world, Long-period world, Its star is visible to the naked eye 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.