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Uncommon exoplanet 28 EP

HIP 9618 b

RA 30.9050° · Dec 21.2813° · exoplanet

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Score breakdown

· 5 badges
28 pts · Uncommon
Uncommon 34 pts → Rare
  • Orbits a Sun-like star +8
  • Multi-planet system +6
  • Confirmed exoplanet +5
  • Sub-Neptune +5
  • Found by TESS +4
Total score 28

6 more points to reach Rare.

Badges

  • Confirmed exoplanet · +5
  • Sub-Neptune · +5
  • Multi-planet system · +6
  • Found by TESS · +4
  • 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 9.2 you'll want a small backyard telescope.
  • 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 October — that's when to go looking.

Properties

density gcc
0.81
diameter km
48835.5972
discovery facility
Transiting Exoplanet Survey Satellite (TESS)
discovery method
Transit
discovery year
2023
dist ly
220.3112
eccentricity
0
eq temp k
640.88
host star teff
5649
insolation
40.3
mag
9.2
mass earth
8.3
name
HIP 9618 b
orbital period days
20.7729
radius earth
3.8284
semi major au
0.145
sys num planets
2
sys num stars
1

About HIP 9618 b

HIP 9618 b is an uncommon exoplanet. It lies about 220.3 light-years from Earth, shines at apparent magnitude 9.2, has an equilibrium temperature near 641 K and spans roughly 3.83 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 9.2, a small backyard telescope will bring it into view.

Like any astronomical target, HIP 9618 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 HIP 9618 b is an uncommon exoplanet

HIP 9618 b scores 28 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 6 points would lift it into a rarer tier.

That score comes from 5 science badges — Confirmed exoplanet, Sub-Neptune, Multi-planet system, Found by TESS 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.