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Common exoplanet 15 EP

HD 156668 c

RA 259.4183° · Dec 29.2282° · exoplanet

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Score breakdown

· 3 badges
15 pts · Common
Common 22 pts → Uncommon
  • Multi-planet system +6
  • Confirmed exoplanet +5
  • Gas giant +4
Total score 15

7 more points to reach Uncommon.

Badges

  • Confirmed exoplanet · +5
  • Gas giant · +4
  • Multi-planet system · +6

Trivia

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.
  • 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
0.737
diameter km
78705.754
discovery facility
Multiple Observatories
discovery method
Radial Velocity
discovery year
2021
dist ly
79.3613
eccentricity
0.089
eq temp k
166.08
host star teff
4903.69
insolation
0.1169
mag
8.43
mass earth
31.4968
name
HD 156668 c
orbital period days
811.3
radius earth
6.17
semi major au
1.57
spect
K2
sys num planets
2
sys num stars
1

Nearby objects

About HD 156668 c

HD 156668 c is a common 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 166 K.

Lighter than Neptune — a puffed-up ball of hydrogen and helium with no surface anywhere on it to stand on.

How to see it

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

Like any astronomical target, HD 156668 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 156668 c is a common exoplanet

HD 156668 c scores 15 points on Spacedle's rarity scale, which places it in the common tier. Another 7 points would lift it into a rarer tier.

That score comes from 3 science badges — Confirmed exoplanet, Gas giant 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.