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Uncommon exoplanet 31 EP

TOI-421 c

RA 81.8533° · Dec -14.2767° · exoplanet

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Score breakdown

· 5 badges
31 pts · Uncommon
Uncommon 34 pts → Rare
  • Two suns in its sky +12
  • Multi-planet system +6
  • Confirmed exoplanet +5
  • Neptune-like +4
  • Found by TESS +4
Total score 31

3 more points to reach Rare.

Badges

  • Confirmed exoplanet · +5
  • Neptune-like · +4
  • Multi-planet system · +6
  • Found by TESS · +4
  • Two suns in its sky · +12

Trivia

Hard to believe

  • It would float. It is less dense than water. Drop it in a big enough ocean and the whole world would bob on the surface.

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.
  • Crowded system. One of at least 2 planets orbiting its star.

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 9.9 you'll want a small backyard telescope.
  • Southern sky. It rides the southern half of the sky — an easier target the further south you are.
  • Best time of year. It stands highest in the middle of the night around December — that's when to go looking.

Properties

density gcc
0.59
diameter km
64929.058
discovery facility
Transiting Exoplanet Survey Satellite (TESS)
discovery method
Transit
discovery year
2020
dist ly
243.9546
eccentricity
0.19
eq temp k
635
host star teff
5291
inclination
88.353
insolation
34.32
mag
9.931
mass earth
14.1
multi star system
yes
name
TOI-421 c
orbital period days
16.0675
radius earth
5.09
semi major au
0.117
spect
G9 V
sys num planets
2
sys num stars
2

About TOI-421 c

TOI-421 c is an uncommon exoplanet. It lies about 244 light-years from Earth, shines at apparent magnitude 9.93, has spectral type G9 V and has an equilibrium temperature near 635 K.

It orbits closer to its star than Mercury does to the Sun, completing a lap in less time than Mercury takes.

How to see it

At apparent magnitude 9.93, a small backyard telescope will bring it into view.

Like any astronomical target, TOI-421 c 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 TOI-421 c is an uncommon exoplanet

TOI-421 c scores 31 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 5 science badges — Confirmed exoplanet, Neptune-like, Multi-planet system, Found by TESS and Two suns in its sky — 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.