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Rare exoplanet 41 EP

HD 187123 c

RA 296.7429° · Dec 34.4190° · exoplanet

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Score breakdown

· 6 badges
41 pts · Rare
Rare 50 pts → Epic
  • Long-period world +10
  • Frozen world +8
  • Orbits a Sun-like star +8
  • Multi-planet system +6
  • Confirmed exoplanet +5
  • Gas giant +4
Total score 41

9 more points to reach Epic.

Badges

  • Confirmed exoplanet · +5
  • Gas giant · +4
  • Frozen world · +8
  • Long-period world · +10
  • Multi-planet system · +6
  • 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.

What it actually is

  • What it is made of. Too light to be solid rock and too heavy to be all gas: most likely a deep global ocean or a thick steamy envelope over a rocky core.
  • Crowded system. One of at least 2 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 7.8 it is just past naked-eye reach — ordinary binoculars will pull it in.
  • 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 July — that's when to go looking.

Could we get there?

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

Properties

density gcc
2.18
diameter km
168381.84
discovery facility
W. M. Keck Observatory
discovery method
Radial Velocity
discovery year
2008
dist ly
149.8843
eccentricity
0.252
eq temp k
135.42
host star teff
5790
inclination
137.2
insolation
0.056
mag
7.83
mass earth
912.1675
name
HD 187123 c
orbital period days
3810
radius earth
13.2
semi major au
4.89
spect
G3 V
sys num planets
2
sys num stars
1

About HD 187123 c

HD 187123 c is a rare exoplanet. It lies about 149.9 light-years from Earth, shines at apparent magnitude 7.83, has spectral type G3 V and has an equilibrium temperature near 135 K.

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

How to see it

At apparent magnitude 7.83, it is an easy target for binoculars.

Like any astronomical target, HD 187123 c 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 187123 c is a rare exoplanet

HD 187123 c scores 41 points on Spacedle's rarity scale, which places it in the rare tier. Another 9 points would lift it into a rarer tier.

That score comes from 6 science badges — Confirmed exoplanet, Gas giant, Frozen world, Long-period world, Multi-planet system 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.