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Rare exoplanet 37 EP

HIP 91258 b

RA 279.2211° · Dec 61.7015° · exoplanet

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Score breakdown

· 5 badges
37 pts · Rare
Rare 50 pts → Epic
  • Hot Jupiter +10
  • Tidally locked +10
  • Orbits a Sun-like star +8
  • Confirmed exoplanet +5
  • Gas giant +4
Total score 37

13 more points to reach Epic.

Badges

  • Confirmed exoplanet · +5
  • Gas giant · +4
  • Hot Jupiter · +10
  • Tidally locked · +10
  • 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.

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 8.7 it is just past naked-eye reach — ordinary binoculars will pull it in.
  • Never sets. So far north that from Britain, Canada or northern Europe it never dips below the horizon — it is up every clear night of the year.
  • Best time of year. It stands highest in the middle of the night around June — that's when to go looking.

Could we get there?

  • Verdict. Hopelessly far for any craft humanity can build today.

Properties

density gcc
0.74
diameter km
174759.94
discovery facility
Haute-Provence Observatory
discovery method
Radial Velocity
discovery year
2013
dist ly
149.6554
eccentricity
0.02
eq temp k
1024.97
host star teff
5519
insolation
166.6086
mag
8.65
mass earth
346.4347
name
HIP 91258 b
orbital period days
5.0505
radius earth
13.7
semi major au
0.06
spect
G5 V
sys num planets
1
sys num stars
1
tidally locked
yes
tidally locked inferred
yes

About HIP 91258 b

HIP 91258 b is a rare exoplanet. It lies about 149.7 light-years from Earth, shines at apparent magnitude 8.65, has spectral type G5 V and has an equilibrium temperature near 1,025 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 8.65, it is an easy target for binoculars.

Like any astronomical target, HIP 91258 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 91258 b is a rare exoplanet

HIP 91258 b scores 37 points on Spacedle's rarity scale, which places it in the rare tier. Another 13 points would lift it into a rarer tier.

That score comes from 5 science badges — Confirmed exoplanet, Gas giant, Hot Jupiter, Tidally locked 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.