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Epic exoplanet 57 EP

TOI-858 B b

RA 60.1998° · Dec -54.5929° · exoplanet

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Score breakdown

· 7 badges
57 pts · Epic
Epic 78 pts → Anomaly
  • Lava world +14
  • Two suns in its sky +12
  • Tidally locked +10
  • Orbits a Sun-like star +8
  • Confirmed exoplanet +5
  • Gas giant +4
  • Found by TESS +4
Total score 57

21 more points to reach Anomaly.

Badges

  • Confirmed exoplanet · +5
  • Gas giant · +4
  • Lava world · +14
  • Tidally locked · +10
  • Found by TESS · +4
  • Orbits a Sun-like star · +8
  • Two suns in its sky · +12

Trivia

What makes it special

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

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.

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 11.2 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 November — that's when to go looking.

Properties

density gcc
0.69
diameter km
179444.9195
discovery facility
Transiting Exoplanet Survey Satellite (TESS)
discovery method
Transit
discovery year
2023
dist ly
816.9849
eccentricity
0.15
eq temp k
1529
host star teff
5842
inclination
86.8
insolation
908.9
mag
11.183
mass earth
349.6112
multi star system
yes
name
TOI-858 B b
orbital period days
3.2797
radius earth
14.0673
semi major au
0.0444
spect
G0
sys num planets
1
sys num stars
2
tidally locked
yes
tidally locked inferred
yes

About TOI-858 B b

TOI-858 B b is an epic exoplanet. It lies about 817 light-years from Earth, shines at apparent magnitude 11.18, has spectral type G0 and has an equilibrium temperature near 1,529 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 11.18, a small backyard telescope will bring it into view.

Like any astronomical target, TOI-858 B 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 TOI-858 B b is an epic exoplanet

TOI-858 B b scores 57 points on Spacedle's rarity scale, which places it in the epic tier. Another 21 points would lift it into a rarer tier.

That score comes from 7 science badges — Confirmed exoplanet, Gas giant, Lava world, Tidally locked, Found by TESS, Orbits a Sun-like star 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.