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Rare exoplanet 47 EP

HAT-P-31 b

RA 271.5377° · Dec 26.4266° · exoplanet

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Score breakdown

· 6 badges
47 pts · Rare
Rare 50 pts → Epic
  • Lava world +14
  • Tidally locked +10
  • Orbits a Sun-like star +8
  • Distant (over 1,000 light-years) +6
  • Confirmed exoplanet +5
  • Gas giant +4
Total score 47

3 more points to reach Epic.

Badges

  • Confirmed exoplanet · +5
  • Distant (over 1,000 light-years) · +6
  • Gas giant · +4
  • Lava world · +14
  • Tidally locked · +10
  • Orbits a Sun-like star · +8

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.

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 11.7 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 June — that's when to go looking.

Could we get there?

  • Verdict. Impossible with our current technology — and the next millennium of it.

Properties

density gcc
2.18
diameter km
155852.8279
discovery facility
HATNet
discovery method
Transit
discovery year
2011
dist ly
1122.1397
eccentricity
0.25
eq temp k
1450
host star teff
6065
inclination
87.1
insolation
746.9025
mag
11.667
mass earth
721.4741
name
HAT-P-31 b
orbital period days
5.0054
radius earth
12.2178
semi major au
0.061
sys num planets
1
sys num stars
1
tidally locked
yes
tidally locked inferred
yes

About HAT-P-31 b

HAT-P-31 b is a rare exoplanet. It lies about 1,122.1 light-years from Earth, shines at apparent magnitude 11.67, has an equilibrium temperature near 1,450 K and spans roughly 12.22 Earth radii.

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

How to see it

At apparent magnitude 11.67, a small backyard telescope will bring it into view.

Like any astronomical target, HAT-P-31 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 HAT-P-31 b is a rare exoplanet

HAT-P-31 b scores 47 points on Spacedle's rarity scale, which places it in the rare tier. Another 3 points would lift it into a rarer tier.

That score comes from 6 science badges — Confirmed exoplanet, Distant (over 1,000 light-years), Gas giant, Lava world, 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.