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Rare exoplanet 43 EP

CoRoT-21 b

RA 101.0526° · Dec -0.2992° · exoplanet

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Score breakdown

· 6 badges
43 pts · Rare
Rare 50 pts → Epic
  • Lava world +14
  • Tidally locked +10
  • Distant (over 1,000 light-years) +6
  • Confirmed exoplanet +5
  • Gas giant +4
  • Blasted by starlight +4
Total score 43

7 more points to reach Epic.

Badges

  • Confirmed exoplanet · +5
  • Distant (over 1,000 light-years) · +6
  • Gas giant · +4
  • Lava world · +14
  • Tidally locked · +10
  • Blasted by starlight · +4

Trivia

What makes it special

  • Lava world. Its surface is almost certainly an ocean of molten rock, kept liquid by the star it hugs.

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. Lighter than Neptune — a puffed-up ball of hydrogen and helium with no surface anywhere on it to stand on.

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 16.1 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 December — that's when to go looking.

Could we get there?

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

Properties

density gcc
1.36
diameter km
185879.5195
discovery facility
CoRoT
discovery method
Transit
discovery year
2012
dist ly
4562.3817
eccentricity
0
eq temp k
2044.44
host star teff
6200
inclination
86.8
insolation
2915.5997
mag
16.058
mass earth
718.2958
name
CoRoT-21 b
orbital period days
2.7247
radius earth
14.5717
semi major au
0.0417
spect
F8 IV
sys num planets
1
sys num stars
1
tidally locked
yes
tidally locked inferred
yes

About CoRoT-21 b

CoRoT-21 b is a rare exoplanet. It lies about 4,562.4 light-years from Earth, shines at apparent magnitude 16.06, has spectral type F8 IV and has an equilibrium temperature near 2,044 K.

Its surface is almost certainly an ocean of molten rock, kept liquid by the star it hugs.

How to see it

At apparent magnitude 16.06, it takes a larger telescope or a long-exposure image to capture.

Like any astronomical target, CoRoT-21 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 CoRoT-21 b is a rare exoplanet

CoRoT-21 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 6 science badges — Confirmed exoplanet, Distant (over 1,000 light-years), Gas giant, Lava world, Tidally locked and Blasted by starlight — 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.