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Uncommon exoplanet 23 EP

HD 105618 b

RA 182.4021° · Dec 11.2116° · exoplanet

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Score breakdown

· 4 badges
23 pts · Uncommon
Uncommon 34 pts → Rare
  • Orbits a Sun-like star +8
  • Multi-planet system +6
  • Confirmed exoplanet +5
  • Neptune-like +4
Total score 23

11 more points to reach Rare.

Badges

  • Confirmed exoplanet · +5
  • Neptune-like · +4
  • Multi-planet system · +6
  • Orbits a Sun-like star · +8

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 8.6 it is just past naked-eye reach — ordinary binoculars will pull it in.
  • 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 March — that's when to go looking.

Properties

density gcc
0.868
diameter km
69393.728
discovery facility
Multiple Observatories
discovery method
Radial Velocity
discovery year
2022
dist ly
228.5822
eccentricity
0.455
eq temp k
1023.19
host star teff
5671
insolation
182.6347
mag
8.63
mass earth
25.4263
name
HD 105618 b
orbital period days
10.0224
radius earth
5.44
semi major au
0.091
sys num planets
2
sys num stars
1

About HD 105618 b

HD 105618 b is an uncommon exoplanet. It lies about 228.6 light-years from Earth, shines at apparent magnitude 8.63, has an equilibrium temperature near 1,023 K and spans roughly 5.44 Earth radii.

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 8.63, it is an easy target for binoculars.

Like any astronomical target, HD 105618 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 HD 105618 b is an uncommon exoplanet

HD 105618 b scores 23 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 11 points would lift it into a rarer tier.

That score comes from 4 science badges — Confirmed exoplanet, Neptune-like, Multi-planet system and Orbits a Sun-like star — 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.