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Rare exoplanet 45 EP

LP 791-18 d

RA 165.6905° · Dec -16.4064° · exoplanet

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Score breakdown

· 5 badges
45 pts · Rare
Rare 50 pts → Epic
  • Earth-sized +16
  • Tidally locked +10
  • Orbits a red dwarf +8
  • Multi-planet system +6
  • Confirmed exoplanet +5
Total score 45

5 more points to reach Epic.

Badges

  • Confirmed exoplanet · +5
  • Earth-sized · +16
  • Tidally locked · +10
  • Multi-planet system · +6
  • Orbits a red dwarf · +8

Trivia

What makes it special

  • Earth-sized. Genuinely comparable to Earth in size. Worlds in this narrow band are the ones every next-generation telescope is being pointed at.

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. Its density says rock, though lighter than Earth's mix: probably less iron, or a thick shell of water and ice over the top.
  • Crowded system. One of at least 3 planets orbiting its star.

Sense of scale

  • In perspective. Inside our stellar backyard: every radio broadcast humanity has ever made has already swept past it.

Find it in the sky

  • How to spot it. At magnitude 16.9 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 March — that's when to go looking.

Properties

density gcc
4.56
diameter km
13164.3984
discovery facility
Spitzer Space Telescope
discovery method
Transit
discovery year
2023
dist ly
86.4075
eccentricity
0.0011
eq temp k
395.5
host star teff
2960
inclination
89.34
insolation
5.83
mag
16.91
mass earth
0.91
name
LP 791-18 d
orbital period days
2.7548
radius earth
1.032
semi major au
0.0199
spect
M(6.1 +/- 0.7) V
sys num planets
3
sys num stars
1
tidally locked
yes
tidally locked inferred
yes

About LP 791-18 d

LP 791-18 d is a rare exoplanet. It lies about 86.4 light-years from Earth, shines at apparent magnitude 16.91, has spectral type M(6.1 +/- 0.7) V and has an equilibrium temperature near 396 K.

Genuinely comparable to Earth in size. Worlds in this narrow band are the ones every next-generation telescope is being pointed at.

How to see it

At apparent magnitude 16.91, it takes a larger telescope or a long-exposure image to capture.

Like any astronomical target, LP 791-18 d 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 LP 791-18 d is a rare exoplanet

LP 791-18 d scores 45 points on Spacedle's rarity scale, which places it in the rare tier. Another 5 points would lift it into a rarer tier.

That score comes from 5 science badges — Confirmed exoplanet, Earth-sized, Tidally locked, Multi-planet system and Orbits a red dwarf — 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.