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Epic exoplanet 65 EP

HD 202772 A b

RA 319.6996° · Dec -26.6164° · exoplanet

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Score breakdown

· 8 badges
65 pts · Epic
Epic 78 pts → Anomaly
  • Lava world +14
  • Puffy low-density world +12
  • Two suns in its sky +12
  • Tidally locked +10
  • Confirmed exoplanet +5
  • Gas giant +4
  • Blasted by starlight +4
  • Found by TESS +4
Total score 65

13 more points to reach Anomaly.

Badges

  • Confirmed exoplanet · +5
  • Gas giant · +4
  • Lava world · +14
  • Tidally locked · +10
  • Puffy low-density world · +12
  • Blasted by starlight · +4
  • 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.

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 8.3 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 August — that's when to go looking.

Properties

density gcc
0.293
diameter km
232634.9674
discovery facility
Transiting Exoplanet Survey Satellite (TESS)
discovery method
Transit
discovery year
2019
dist ly
526.7354
eccentricity
0.03
eq temp k
2181
host star teff
6442
inclination
84.9
insolation
3770
mag
8.324
mass earth
323.5493
multi star system
yes
name
HD 202772 A b
orbital period days
3.3089
radius earth
18.237
semi major au
0.0521
sys num planets
1
sys num stars
2
tidally locked
yes
tidally locked inferred
yes

About HD 202772 A b

HD 202772 A b is an epic exoplanet. It lies about 526.7 light-years from Earth, shines at apparent magnitude 8.32, has an equilibrium temperature near 2,181 K and spans roughly 18.24 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 8.32, it is an easy target for binoculars.

Like any astronomical target, HD 202772 A 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 202772 A b is an epic exoplanet

HD 202772 A b scores 65 points on Spacedle's rarity scale, which places it in the epic tier. Another 13 points would lift it into a rarer tier.

That score comes from 8 science badges — Confirmed exoplanet, Gas giant, Lava world, Tidally locked, Puffy low-density world, Blasted by starlight, 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.