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Epic exoplanet 56 EP

HR 858 b

RA 42.9850° · Dec -30.8141° · exoplanet

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Score breakdown

· 7 badges
56 pts · Epic
Epic 78 pts → Anomaly
  • Lava world +14
  • Two suns in its sky +12
  • Tidally locked +10
  • Multi-planet system +6
  • Confirmed exoplanet +5
  • Sub-Neptune +5
  • Found by TESS +4
Total score 56

22 more points to reach Anomaly.

Badges

  • Confirmed exoplanet · +5
  • Sub-Neptune · +5
  • Lava world · +14
  • Tidally locked · +10
  • Multi-planet system · +6
  • Found by TESS · +4
  • 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.

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. Too light to be solid rock and too heavy to be all gas: most likely a deep global ocean or a thick steamy envelope over a rocky core.
  • Crowded system. One of at least 3 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 6.4 it is just past naked-eye reach — ordinary binoculars will pull it in.
  • 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
2.44
diameter km
25563.4248
discovery facility
Transiting Exoplanet Survey Satellite (TESS)
discovery method
Transit
discovery year
2019
dist ly
104.2525
eccentricity
0
eq temp k
1552
host star teff
6354
inclination
85.98
insolation
989.7
mag
6.38
mass earth
3.55
multi star system
yes
name
HR 858 b
orbital period days
3.5853
radius earth
2.004
semi major au
0.0489
spect
F6 V
sys num planets
3
sys num stars
2
tidally locked
yes
tidally locked inferred
yes

About HR 858 b

HR 858 b is an epic exoplanet. It lies about 104.3 light-years from Earth, shines at apparent magnitude 6.38, has spectral type F6 V and has an equilibrium temperature near 1,552 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 6.38, it is an easy target for binoculars.

Like any astronomical target, HR 858 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 HR 858 b is an epic exoplanet

HR 858 b scores 56 points on Spacedle's rarity scale, which places it in the epic tier. Another 22 points would lift it into a rarer tier.

That score comes from 7 science badges — Confirmed exoplanet, Sub-Neptune, Lava world, Tidally locked, 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.