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Epic exoplanet 57 EP

KELT-21 b

RA 304.8000° · Dec 32.5810° · exoplanet

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Score breakdown

· 7 badges
57 pts · Epic
Epic 78 pts → Anomaly
  • Lava world +14
  • Orbits a hot blue-white star +14
  • Tidally locked +10
  • Distant (over 1,000 light-years) +6
  • Confirmed exoplanet +5
  • Gas giant +4
  • Blasted by starlight +4
Total score 57

21 more points to reach Anomaly.

Badges

  • Confirmed exoplanet · +5
  • Distant (over 1,000 light-years) · +6
  • Gas giant · +4
  • Lava world · +14
  • Tidally locked · +10
  • Blasted by starlight · +4
  • Orbits a hot blue-white star · +14

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. 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 10.5 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 July — that's when to go looking.

Could we get there?

  • Verdict. Impossible with our current technology — and the next millennium of it.

Properties

density gcc
1.24
diameter km
226773.0138
discovery facility
KELT-North
discovery method
Transit
discovery year
2018
dist ly
1535.7968
eccentricity
0
eq temp k
2051
host star teff
7598
inclination
86.46
insolation
2950
mag
10.484
mass earth
1242.7153
name
KELT-21 b
orbital period days
3.6128
radius earth
17.7775
semi major au
0.0522
spect
A8 V
sys num planets
1
sys num stars
1
tidally locked
yes
tidally locked inferred
yes

About KELT-21 b

KELT-21 b is an epic exoplanet. It lies about 1,535.8 light-years from Earth, shines at apparent magnitude 10.48, has spectral type A8 V and has an equilibrium temperature near 2,051 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 10.48, a small backyard telescope will bring it into view.

Like any astronomical target, KELT-21 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-21 b is an epic exoplanet

KELT-21 b scores 57 points on Spacedle's rarity scale, which places it in the epic tier. Another 21 points would lift it into a rarer tier.

That score comes from 7 science badges — Confirmed exoplanet, Distant (over 1,000 light-years), Gas giant, Lava world, Tidally locked, Blasted by starlight and Orbits a hot blue-white 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.