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Rare exoplanet 36 EP

HD 191939 c

RA 302.0256° · Dec 66.8503° · exoplanet

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Score breakdown

· 5 badges
36 pts · Rare
Rare 50 pts → Epic
  • Richly packed system +14
  • Orbits a Sun-like star +8
  • Confirmed exoplanet +5
  • Sub-Neptune +5
  • Found by TESS +4
Total score 36

14 more points to reach Epic.

Badges

  • Confirmed exoplanet · +5
  • Sub-Neptune · +5
  • Richly packed system · +14
  • Found by TESS · +4
  • Orbits a Sun-like star · +8

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. 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 6 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 9 it is just past naked-eye reach — ordinary binoculars will pull it in.
  • Never sets. So far north that from Britain, Canada or northern Europe it never dips below the horizon — it is up every clear night of the year.
  • 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
1.35
diameter km
40756.059
discovery facility
Transiting Exoplanet Survey Satellite (TESS)
discovery method
Transit
discovery year
2020
dist ly
174.8486
eccentricity
0.034
eq temp k
600
host star teff
5348
inclination
89.1
insolation
21
mag
8.97
mass earth
8
name
HD 191939 c
orbital period days
28.5797
radius earth
3.195
semi major au
0.1752
spect
G9 V
sys num planets
6
sys num stars
1

About HD 191939 c

HD 191939 c is a rare exoplanet. It lies about 174.8 light-years from Earth, shines at apparent magnitude 8.97, has spectral type G9 V and has an equilibrium temperature near 600 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 8.97, it is an easy target for binoculars.

Like any astronomical target, HD 191939 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 191939 c is a rare exoplanet

HD 191939 c scores 36 points on Spacedle's rarity scale, which places it in the rare tier. Another 14 points would lift it into a rarer tier.

That score comes from 5 science badges — Confirmed exoplanet, Sub-Neptune, Richly packed system, Found by TESS 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.