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Rare exoplanet 43 EP

SPECULOOS-3 b

RA 312.3633° · Dec 33.6124° · exoplanet

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Score breakdown

· 4 badges
43 pts · Rare
Rare 50 pts → Epic
  • Earth-sized +16
  • Ultra-short period +14
  • Orbits a red dwarf +8
  • Confirmed exoplanet +5
Total score 43

7 more points to reach Epic.

Badges

  • Confirmed exoplanet · +5
  • Earth-sized · +16
  • Ultra-short period · +14
  • Orbits a red dwarf · +8

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.

Hard to believe

  • A year in a day. Its entire year is over in 17.3 hours. Birthdays here would come round faster than meals.

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. Its density says rock, though lighter than Earth's mix: probably less iron, or a thick shell of water and ice over the top.

Find it in the sky

  • How to spot it. At magnitude 17.8 it is far too faint for the eye: this one belongs to cameras and long exposures.
  • Northern sky. It rides the northern half of the sky — an easier target the further north you are.
  • Best time of year. It stands highest in the middle of the night around August — that's when to go looking.

Standing on it

  • A year here. A full year lasts just 0.7 Earth days.

Properties

density gcc
5.27
diameter km
12462.8074
discovery facility
SPECULOOS Southern Observatory
discovery method
Transit
discovery year
2024
eq temp k
553
host star teff
2800
inclination
89.44
insolation
15.54
mag
17.8
mass earth
0.894
name
SPECULOOS-3 b
orbital period days
0.7191
radius earth
0.977
semi major au
0.0073
spect
M6.5+/-0.5
sys num planets
1
sys num stars
1
tidally locked
yes
tidally locked inferred
yes

About SPECULOOS-3 b

SPECULOOS-3 b is a rare exoplanet. It shines at apparent magnitude 17.8, has spectral type M6.5+/-0.5, has an equilibrium temperature near 553 K and spans roughly 0.98 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 17.8, it takes a larger telescope or a long-exposure image to capture.

Like any astronomical target, SPECULOOS-3 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 SPECULOOS-3 b is a rare exoplanet

SPECULOOS-3 b scores 43 points on Spacedle's rarity scale, which places it in the rare tier. Another 7 points would lift it into a rarer tier.

That score comes from 4 science badges — Confirmed exoplanet, Earth-sized, Ultra-short period and Orbits a red dwarf — 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.