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Common exoplanet 21 EP

K2-400 b

RA 154.5110° · Dec 3.6969° · exoplanet

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Score breakdown

· 2 badges
21 pts · Common
Common 22 pts → Uncommon
  • Earth-sized +16
  • Confirmed exoplanet +5
Total score 21

1 more point to reach Uncommon.

Badges

  • Confirmed exoplanet · +5
  • Earth-sized · +16

Trivia

What makes it special

  • Earth-sized. Genuinely comparable to Earth in size. Worlds in this narrow band are the ones every next-generation telescope is being pointed at.

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. 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 15.1 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 February — that's when to go looking.

Could we get there?

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

Properties

density gcc
5.83
diameter km
14835.4606
discovery facility
K2
discovery method
Transit
discovery year
2022
dist ly
203.4574
host star teff
3578
mag
15.108
mass earth
1.67
name
K2-400 b
orbital period days
3.8651
radius earth
1.163
spect
M3
sys num planets
1
sys num stars
1

Nearby objects

About K2-400 b

K2-400 b is a common exoplanet. It lies about 203.5 light-years from Earth, shines at apparent magnitude 15.11, has spectral type M3 and spans roughly 1.16 Earth radii.

Genuinely comparable to Earth in size. Worlds in this narrow band are the ones every next-generation telescope is being pointed at.

How to see it

At apparent magnitude 15.11, it takes a larger telescope or a long-exposure image to capture.

Like any astronomical target, K2-400 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 K2-400 b is a common exoplanet

K2-400 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 2 science badges — Confirmed exoplanet and Earth-sized — 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.