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Rare exoplanet 37 EP

XO-3 b

RA 65.4696° · Dec 57.8172° · exoplanet

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Score breakdown

· 5 badges
37 pts · Rare
Rare 50 pts → Epic
  • Lava world +14
  • Tidally locked +10
  • Confirmed exoplanet +5
  • Gas giant +4
  • Blasted by starlight +4
Total score 37

13 more points to reach Epic.

Badges

  • Confirmed exoplanet · +5
  • Gas giant · +4
  • Lava world · +14
  • Tidally locked · +10
  • Blasted by starlight · +4

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. Denser than Earth — a solid world of rock and iron, with no meaningful atmosphere to speak of by mass.

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 9.9 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 November — that's when to go looking.

Could we get there?

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

Properties

density gcc
7.16
diameter km
188738.8794
discovery facility
XO
discovery method
Transit
discovery year
2007
dist ly
694.8851
eccentricity
0.2791
eq temp k
1890
host star teff
6970
inclination
83.66
insolation
1161.72
mag
9.854
mass earth
4217.583
name
XO-3 b
orbital period days
3.1915
radius earth
14.7959
semi major au
0.0481
spect
F5V
sys num planets
1
sys num stars
1
tidally locked
yes
tidally locked inferred
yes

About XO-3 b

XO-3 b is a rare exoplanet. It lies about 694.9 light-years from Earth, shines at apparent magnitude 9.85, has spectral type F5V and has an equilibrium temperature near 1,890 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 9.85, a small backyard telescope will bring it into view.

Like any astronomical target, XO-3 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 XO-3 b is a rare exoplanet

XO-3 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, Lava world, Tidally locked and Blasted by starlight — 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.