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Common exoplanet 21 EP

HD 219139 b

RA 348.3604° · Dec 11.0650° · 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

  • 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.

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.
  • 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 September — 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 million years at Voyager 1's speed (17 km/s).

Properties

density gcc
0.496
diameter km
178586.8
discovery facility
Okayama Astrophysical Observatory
discovery method
Radial Velocity
discovery year
2021
dist ly
342.2518
eccentricity
0.11
eq temp k
804.83
host star teff
4831
insolation
70.5297
mag
5.8486
mass earth
247.9062
name
HD 219139 b
orbital period days
275.5
radius earth
14
semi major au
0.94
spect
G5 III
sys num planets
1
sys num stars
1

About HD 219139 b

HD 219139 b is a common exoplanet. It lies about 342.3 light-years from Earth, shines at apparent magnitude 5.85, has spectral type G5 III and has an equilibrium temperature near 805 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 5.85, it can be glimpsed with the unaided eye under dark skies.

Like any astronomical target, HD 219139 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 219139 b is a common exoplanet

HD 219139 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.