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Uncommon exoplanet 29 EP

HD 156668 b

RA 259.4183° · Dec 29.2282° · exoplanet

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Score breakdown

· 4 badges
29 pts · Uncommon
Uncommon 34 pts → Rare
  • Tidally locked +10
  • Super-Earth +8
  • Multi-planet system +6
  • Confirmed exoplanet +5
Total score 29

5 more points to reach Rare.

Badges

  • Confirmed exoplanet · +5
  • Super-Earth · +8
  • Tidally locked · +10
  • Multi-planet system · +6

Trivia

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. Its density says rock, though lighter than Earth's mix: probably less iron, or a thick shell of water and ice over the top.
  • Crowded system. One of at least 2 planets orbiting its star.

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 8.4 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 June — that's when to go looking.

Could we get there?

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

Properties

density gcc
3.49
diameter km
23854.094
discovery facility
W. M. Keck Observatory
discovery method
Radial Velocity
discovery year
2010
dist ly
79.3613
eccentricity
0
eq temp k
887.48
host star teff
4850
insolation
679.2975
mag
8.43
mass earth
4.15
name
HD 156668 b
orbital period days
4.6455
radius earth
1.87
semi major au
0.05
spect
K2
sys num planets
2
sys num stars
1
tidally locked
yes
tidally locked inferred
yes

About HD 156668 b

HD 156668 b is an uncommon exoplanet. It lies about 79.4 light-years from Earth, shines at apparent magnitude 8.43, has spectral type K2 and has an equilibrium temperature near 887 K.

It orbits closer to its star than Mercury does to the Sun, completing a lap in less time than Mercury takes.

How to see it

At apparent magnitude 8.43, it is an easy target for binoculars.

Like any astronomical target, HD 156668 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 156668 b is an uncommon exoplanet

HD 156668 b scores 29 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 5 points would lift it into a rarer tier.

That score comes from 4 science badges — Confirmed exoplanet, Super-Earth, Tidally locked and Multi-planet system — 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.