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Common exoplanet 21 EP

HD 139357 b

RA 233.8174° · Dec 53.9222° · exoplanet

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Score breakdown

· 3 badges
21 pts · Common
Common 22 pts → Uncommon
  • Its star is visible to the naked eye +12
  • Confirmed exoplanet +5
  • Gas giant +4
Total score 21

1 more point to reach Uncommon.

Badges

  • Confirmed exoplanet · +5
  • Gas giant · +4
  • Its star is visible to the naked eye · +12

Trivia

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 6 you can see it with your own eyes from a dark site.
  • 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 May — that's when to go looking.

Could we get there?

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

Getting there

  • Aboard Voyager 1. ≈ 6.4 million years at Voyager 1's speed (17 km/s).

Properties

density gcc
19.6
diameter km
154350.02
discovery facility
Thueringer Landessternwarte Tautenburg
discovery method
Radial Velocity
discovery year
2008
dist ly
365.5883
eccentricity
0.099
eq temp k
446.97
host star teff
4700
inclination
103.235
insolation
7.649
mag
5.9727
mass earth
6315.5683
name
HD 139357 b
orbital period days
1124.7914
radius earth
12.1
semi major au
2.949
spect
K4 III
sys num planets
1
sys num stars
1

About HD 139357 b

HD 139357 b is a common exoplanet. It lies about 365.6 light-years from Earth, shines at apparent magnitude 5.97, has spectral type K4 III and has an equilibrium temperature near 447 K.

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

How to see it

At apparent magnitude 5.97, it can be glimpsed with the unaided eye under dark skies.

Like any astronomical target, HD 139357 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 139357 b is a common exoplanet

HD 139357 b scores 21 points on Spacedle's rarity scale, which places it in the common tier. Another 1 point would lift it into a rarer tier.

That score comes from 3 science badges — Confirmed exoplanet, Gas giant and Its star is visible to the naked eye — 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.