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Trash exoplanet 9 EP

K2-405 b

RA 164.3760° · Dec 12.5356° · exoplanet

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Score breakdown

· 2 badges
9 pts · Trash
Trash 15 pts → Common
  • Confirmed exoplanet +5
  • Neptune-like +4
Total score 9

6 more points to reach Common.

Badges

  • Confirmed exoplanet · +5
  • Neptune-like · +4

Trivia

Could we get there?

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

Getting there

  • Aboard Voyager 1. ≈ 11.3 million years at Voyager 1's speed (17 km/s).
  • Fastest probe ever. ≈ 1 million years even at the Parker Solar Probe's 192 km/s.
  • At 10% light speed. ≈ 6433 years in a starship at a tenth of light speed.
  • Distance. 643 light-years from Earth.

Look-back time

  • Look-back time. The light you'd see left around the year 1383.

Saying hello

  • Say hello. A radio message and its reply would take 1287 years round-trip.

Standing on it

  • A year here. A full year lasts just 3.4 Earth days.

By the numbers

  • Size. About 4.6× the width of Earth.
  • Volume. About 95.4 Earths could fit inside it.
  • Mass. About 18.9× the mass of Earth.
  • Your weight. You'd weigh about 0.9× your Earth weight standing here.
  • Temperature. Around 696°C — hotter than a self-cleaning oven.

How we found it

  • Discovery. Found by K2 using the transit method.

Properties

density gcc
1.09
discovery facility
K2
discovery method
Transit
dist ly
643.2905
eq temp k
969
insolation
146.577
mass earth
18.9
name
K2-405 b
orbital period days
3.4355
radius earth
4.569
sys num planets
1

About K2-405 b

K2-405 b is a trash exoplanet. It lies about 643.3 light-years from Earth, has an equilibrium temperature near 969 K, spans roughly 4.57 Earth radii and weighs about 18.9 Earth masses.

About 4.6× the width of Earth.

How to see it

Like any astronomical target, K2-405 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 K2-405 b is a trash exoplanet

K2-405 b scores 9 points on Spacedle's rarity scale, which places it in the trash tier. Another 6 points would lift it into a rarer tier.

That score comes from 2 science badges — Confirmed exoplanet and Neptune-like — 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.

spacedle A daily roll through the real universe. © 2026 spacedle. Buy me a coffee

Sky imagery and survey data courtesy of Aladin Lite & CDS, Strasbourg. Object data from the NASA Exoplanet Archive, JPL Small-Body Database, and the ATNF Pulsar Catalogue.