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Rare exoplanet 49 EP

HAT-P-30 b

RA 123.9498° · Dec 5.8369° · exoplanet

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Score breakdown

· 6 badges
49 pts · Rare
Rare 50 pts → Epic
  • Lava world +14
  • Two suns in its sky +12
  • Tidally locked +10
  • Confirmed exoplanet +5
  • Gas giant +4
  • Blasted by starlight +4
Total score 49

1 more point to reach Epic.

Badges

  • Confirmed exoplanet · +5
  • Gas giant · +4
  • Lava world · +14
  • Tidally locked · +10
  • Blasted by starlight · +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 10.4 you'll want a small backyard telescope.
  • Seen from everywhere. It sits almost on the celestial equator, so it can be seen from essentially anywhere on Earth.
  • Best time of year. It stands highest in the middle of the night around January — that's when to go looking.

Properties

density gcc
0.309
diameter km
205897.314
discovery facility
HATNet
discovery method
Transit
discovery year
2011
dist ly
697.9249
eccentricity
0.04
eq temp k
1630
host star teff
6304
inclination
83.6
insolation
1467.9573
mag
10.352
mass earth
263.7989
multi star system
yes
name
HAT-P-30 b
orbital period days
2.8106
radius earth
16.141
semi major au
0.0419
spect
F7
sys num planets
1
sys num stars
2
tidally locked
yes
tidally locked inferred
yes

About HAT-P-30 b

HAT-P-30 b is a rare exoplanet. It lies about 697.9 light-years from Earth, shines at apparent magnitude 10.35, has spectral type F7 and has an equilibrium temperature near 1,630 K.

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

How to see it

At apparent magnitude 10.35, a small backyard telescope will bring it into view.

Like any astronomical target, HAT-P-30 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-30 b is a rare exoplanet

HAT-P-30 b scores 49 points on Spacedle's rarity scale, which places it in the rare tier. Another 1 point would lift it into a rarer tier.

That score comes from 6 science badges — Confirmed exoplanet, Gas giant, Lava world, Tidally locked, Blasted by starlight 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.