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Rare exoplanet 37 EP

KELT-17 b

RA 125.6174° · Dec 13.7353° · 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.

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 9.2 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 January — that's when to go looking.

Properties

density gcc
0.46
diameter km
218050.9748
discovery facility
KELT
discovery method
Transit
discovery year
2016
dist ly
738.7433
eq temp k
2087
host star teff
7454
inclination
84.87
insolation
3331.8707
mag
9.234
mass earth
416.3573
name
KELT-17 b
orbital period days
3.0802
radius earth
17.0937
semi major au
0.0488
spect
A
sys num planets
1
sys num stars
1
tidally locked
yes
tidally locked inferred
yes

About KELT-17 b

KELT-17 b is a rare exoplanet. It lies about 738.7 light-years from Earth, shines at apparent magnitude 9.23, has spectral type A and has an equilibrium temperature near 2,087 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 9.23, a small backyard telescope will bring it into view.

Like any astronomical target, KELT-17 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 KELT-17 b is a rare exoplanet

KELT-17 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.