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Uncommon exoplanet 29 EP

HD 40307 c

RA 88.5172° · Dec -60.0237° · exoplanet

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Score breakdown

· 3 badges
29 pts · Uncommon
Uncommon 34 pts → Rare
  • Richly packed system +14
  • Tidally locked +10
  • Confirmed exoplanet +5
Total score 29

5 more points to reach Rare.

Badges

  • Confirmed exoplanet · +5
  • Tidally locked · +10
  • Richly packed system · +14

Trivia

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.
  • Crowded system. One of at least 5 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 7.2 it is just past naked-eye reach — ordinary binoculars will pull it in.
  • Southern sky only. So far south it never rises for most of the northern hemisphere. To see it you'd have to travel to Chile, South Africa or Australia.
  • Best time of year. It stands highest in the middle of the night around December — that's when to go looking.

Could we get there?

  • Verdict. Hopelessly far for any craft humanity can build today.

Getting there

  • Aboard Voyager 1. ≈ 741.4 thousand years at Voyager 1's speed (17 km/s).

Properties

discovery facility
La Silla Observatory
discovery method
Radial Velocity
discovery year
2009
dist ly
42.1925
eccentricity
0.06
eq temp k
696
host star teff
4956
inclination
0.2109
insolation
35.9672
mag
7.17
mass earth
1868.5132
name
HD 40307 c
orbital period days
9.6184
semi major au
0.0799
spect
K2.5 V
sys num planets
5
sys num stars
1
tidally locked
yes
tidally locked inferred
yes

About HD 40307 c

HD 40307 c is an uncommon exoplanet. It lies about 42.2 light-years from Earth, shines at apparent magnitude 7.17, has spectral type K2.5 V and has an equilibrium temperature near 696 K.

It orbits closer to its star than Mercury does to the Sun, completing a lap in less time than Mercury takes.

How to see it

At apparent magnitude 7.17, it is an easy target for binoculars.

Like any astronomical target, HD 40307 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 HD 40307 c is an uncommon exoplanet

HD 40307 c scores 29 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 5 points would lift it into a rarer tier.

That score comes from 3 science badges — Confirmed exoplanet, Tidally locked and Richly packed system — 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.