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Rare exoplanet 41 EP

HD 149143 b

RA 248.2127° · Dec 2.0845° · exoplanet

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Score breakdown

· 5 badges
41 pts · Rare
Rare 50 pts → Epic
  • Lava world +14
  • Tidally locked +10
  • Orbits a Sun-like star +8
  • Confirmed exoplanet +5
  • Gas giant +4
Total score 41

9 more points to reach Epic.

Badges

  • Confirmed exoplanet · +5
  • 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.

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 7.9 it is just past naked-eye reach — ordinary binoculars will pull it in.
  • 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 May — that's when to go looking.

Properties

density gcc
0.923
diameter km
173484.32
discovery facility
Haute-Provence Observatory
discovery method
Radial Velocity
discovery year
2005
dist ly
239.0074
eccentricity
0.0167
eq temp k
1471.9
host star teff
5856
insolation
796.9815
mag
7.89
mass earth
422.7139
name
HD 149143 b
orbital period days
4.0718
radius earth
13.6
semi major au
0.053
spect
G0
sys num planets
1
sys num stars
1
tidally locked
yes
tidally locked inferred
yes

About HD 149143 b

HD 149143 b is a rare exoplanet. It lies about 239 light-years from Earth, shines at apparent magnitude 7.89, has spectral type G0 and has an equilibrium temperature near 1,472 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 7.89, it is an easy target for binoculars.

Like any astronomical target, HD 149143 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 149143 b is a rare exoplanet

HD 149143 b scores 41 points on Spacedle's rarity scale, which places it in the rare tier. Another 9 points would lift it into a rarer tier.

That score comes from 5 science badges — Confirmed exoplanet, 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.