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Rare exoplanet 39 EP

NGTS-21 b

RA 311.2583° · Dec -35.4278° · exoplanet

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Score breakdown

· 5 badges
39 pts · Rare
Rare 50 pts → Epic
  • Lava world +14
  • Tidally locked +10
  • Distant (over 1,000 light-years) +6
  • Confirmed exoplanet +5
  • Gas giant +4
Total score 39

11 more points to reach Epic.

Badges

  • Confirmed exoplanet · +5
  • Distant (over 1,000 light-years) · +6
  • Gas giant · +4
  • Lava world · +14
  • Tidally locked · +10

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 15.5 it is far too faint for the eye: this one belongs to cameras and long exposures.
  • Southern sky. It rides the southern half of the sky — an easier target the further south you are.
  • Best time of year. It stands highest in the middle of the night around August — 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
1.25
diameter km
190168.7195
discovery facility
Next-Generation Transit Survey (NGTS)
discovery method
Transit
discovery year
2022
dist ly
1933.7496
eccentricity
0
eq temp k
1357
host star teff
4660
inclination
83.85
insolation
514.2853
mag
15.506
mass earth
750.075
name
NGTS-21 b
orbital period days
1.5434
radius earth
14.9079
semi major au
0.0236
spect
K3 V
sys num planets
1
sys num stars
1
tidally locked
yes
tidally locked inferred
yes

About NGTS-21 b

NGTS-21 b is a rare exoplanet. It lies about 1,933.7 light-years from Earth, shines at apparent magnitude 15.51, has spectral type K3 V and has an equilibrium temperature near 1,357 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 15.51, it takes a larger telescope or a long-exposure image to capture.

Like any astronomical target, NGTS-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 NGTS-21 b is a rare exoplanet

NGTS-21 b scores 39 points on Spacedle's rarity scale, which places it in the rare tier. Another 11 points would lift it into a rarer tier.

That score comes from 5 science badges — Confirmed exoplanet, Distant (over 1,000 light-years), Gas giant, Lava world and Tidally locked — 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.