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Rare exoplanet 41 EP

GJ 317 c

RA 130.2445° · Dec -23.4528° · exoplanet

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Score breakdown

· 6 badges
41 pts · Rare
Rare 50 pts → Epic
  • Long-period world +10
  • Frozen world +8
  • Orbits a red dwarf +8
  • Multi-planet system +6
  • Confirmed exoplanet +5
  • Gas giant +4
Total score 41

9 more points to reach Epic.

Badges

  • Confirmed exoplanet · +5
  • Gas giant · +4
  • Frozen world · +8
  • Long-period world · +10
  • Multi-planet system · +6
  • Orbits a red dwarf · +8

Trivia

What makes it special

  • Frozen world. A deep-frozen world, too far from its star's warmth for anything to stay liquid.

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

  • 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.
  • Crowded system. One of at least 2 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 12.4 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 January — that's when to go looking.

Properties

density gcc
0.993
diameter km
173484.32
discovery facility
W. M. Keck Observatory
discovery method
Radial Velocity
discovery year
2016
dist ly
49.5653
eccentricity
0.217
eq temp k
47.67
host star teff
3496
insolation
0.0008
mag
12.4
mass earth
454.4946
name
GJ 317 c
orbital period days
6500
radius earth
13.6
semi major au
5.04
spect
M3.5 V
sys num planets
2
sys num stars
1

About GJ 317 c

GJ 317 c is a rare exoplanet. It lies about 49.6 light-years from Earth, shines at apparent magnitude 12.4, has spectral type M3.5 V and has an equilibrium temperature near 48 K.

A deep-frozen world, too far from its star's warmth for anything to stay liquid.

How to see it

At apparent magnitude 12.4, it takes a larger telescope or a long-exposure image to capture.

Like any astronomical target, GJ 317 c 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 GJ 317 c is a rare exoplanet

GJ 317 c scores 41 points on Spacedle's rarity scale, which places it in the rare tier. Another 9 points would lift it into a rarer tier.

That score comes from 6 science badges — Confirmed exoplanet, Gas giant, Frozen world, Long-period world, 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.