← Back to dex
Rare exoplanet 34 EP

K2-204 b

RA 17.3825° · Dec -0.5178° · exoplanet

Loading sky survey…
🌌 View in 3D star map
Tonight’s visibility

Computing the sky for your location…

Score breakdown

· 5 badges
34 pts · Rare
Rare 50 pts → Epic
  • Tidally locked +10
  • Orbits a Sun-like star +8
  • Distant (over 1,000 light-years) +6
  • Confirmed exoplanet +5
  • Sub-Neptune +5
Total score 34

16 more points to reach Epic.

Badges

  • Confirmed exoplanet · +5
  • Distant (over 1,000 light-years) · +6
  • Sub-Neptune · +5
  • Tidally locked · +10
  • 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. Too light to be solid rock and too heavy to be all gas: most likely a deep global ocean or a thick steamy envelope over a rocky core.

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 13 it is far too faint for the eye: this one belongs to cameras and long exposures.
  • Seen from everywhere. It sits almost on the celestial equator, so it can be seen from essentially anywhere on Earth.
  • Best time of year. It stands highest in the middle of the night around October — that's when to go looking.

Could we get there?

  • Verdict. Impossible with our current technology — and the next millennium of it.

Getting there

  • Aboard Voyager 1. ≈ 33.1 million years at Voyager 1's speed (17 km/s).

Properties

density gcc
1.76
diameter km
40464.4719
discovery facility
K2
discovery method
Transit
discovery year
2018
dist ly
1882.6866
eccentricity
0.28
eq temp k
1148
host star teff
5783
inclination
88.76
insolation
290.0978
mag
12.985
mass earth
10.2
name
K2-204 b
orbital period days
7.0559
radius earth
3.1721
semi major au
0.0738
sys num planets
1
sys num stars
1
tidally locked
yes
tidally locked inferred
yes

About K2-204 b

K2-204 b is a rare exoplanet. It lies about 1,882.7 light-years from Earth, shines at apparent magnitude 12.98, has an equilibrium temperature near 1,148 K and spans roughly 3.17 Earth radii.

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 12.98, it takes a larger telescope or a long-exposure image to capture.

Like any astronomical target, K2-204 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 K2-204 b is a rare exoplanet

K2-204 b scores 34 points on Spacedle's rarity scale, which places it in the rare tier. Another 16 points would lift it into a rarer tier.

That score comes from 5 science badges — Confirmed exoplanet, Distant (over 1,000 light-years), Sub-Neptune, Tidally locked 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.