Uncommon exoplanet 30 EP

K2-138 d

RA 348.9490° · Dec -10.8497° · exoplanet

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Score breakdown

· 4 badges

30 pts · Uncommon

Uncommon 33 pts → Rare

Richly packed system +14
Multi-planet system +6
Confirmed exoplanet +5
Sub-Neptune +5

Total score 30

3 more points to reach Rare.

Badges

Confirmed exoplanet · +5
Sub-Neptune · +5
Multi-planet system · +6
Richly packed system · +14

Trivia

What makes it special

Packed system. Crammed into a system of five or more planets.

Could we get there?

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

Getting there

Aboard Voyager 1. ≈ 11.6 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. ≈ 6607 years in a starship at a tenth of light speed.
Distance. 661 light-years from Earth.

Look-back time

Look-back time. The light you'd see left around the year 1365.

Saying hello

Say hello. A radio message and its reply would take 1321 years round-trip.

Standing on it

A year here. A full year lasts just 5.4 Earth days.

By the numbers

Size. About 2.4× the width of Earth.
Volume. About 13.7 Earths could fit inside it.
Mass. About 7.9× the mass of Earth.
Your weight. You'd weigh about 1.4× your Earth weight standing here.
Temperature. Around 615°C — hotter than a self-cleaning oven.

How we found it

Discovery. Found by K2 using the transit method.

Cosmic context

Crowded system. One of at least 6 planets orbiting its star.

Properties

density gcc: 3.1
discovery facility: K2
discovery method: Transit
dist ly: 660.7431
eccentricity: 0.043
eq temp k: 888
insolation: 160
mass earth: 7.92
name: K2-138 d
orbital period days: 5.4048
radius earth: 2.39
sys num planets: 6

About K2-138 d

K2-138 d is an uncommon exoplanet. It lies about 660.7 light-years from Earth, has an equilibrium temperature near 888 K, spans roughly 2.39 Earth radii and weighs about 7.92 Earth masses.

Crammed into a system of five or more planets.

How to see it

Like any astronomical target, K2-138 d 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 K2-138 d is an uncommon exoplanet

K2-138 d scores 30 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 3 points would lift it into a rarer tier.

That score comes from 4 science badges — Confirmed exoplanet, Sub-Neptune, Multi-planet system and Richly packed system — 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.