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Uncommon exoplanet 30 EP

HD 3651 b

RA 9.8387° · Dec 21.2489° · exoplanet

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Score breakdown

· 4 badges
30 pts · Uncommon
Uncommon 34 pts → Rare
  • Its star is visible to the naked eye +12
  • Eccentric orbit +9
  • Confirmed exoplanet +5
  • Gas giant +4
Total score 30

4 more points to reach Rare.

Badges

  • Confirmed exoplanet · +5
  • Gas giant · +4
  • Eccentric orbit · +9
  • Its star is visible to the naked eye · +12

Trivia

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

  • 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. 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 5.9 you can see it with your own eyes from a dark site.
  • 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 September — that's when to go looking.

Could we get there?

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

Properties

density gcc
0.386
diameter km
128837.62
discovery facility
Multiple Observatories
discovery method
Radial Velocity
discovery year
2003
dist ly
36.3129
eccentricity
0.645
eq temp k
432.84
host star teff
5221
insolation
6.1123
mag
5.8844
mass earth
72.4652
name
HD 3651 b
orbital period days
62.25
radius earth
10.1
semi major au
0.295
spect
K0 V
sys num planets
1
sys num stars
1

About HD 3651 b

HD 3651 b is an uncommon exoplanet. It lies about 36.3 light-years from Earth, shines at apparent magnitude 5.88, has spectral type K0 V and has an equilibrium temperature near 433 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 5.88, it can be glimpsed with the unaided eye under dark skies.

Like any astronomical target, HD 3651 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 HD 3651 b is an uncommon exoplanet

HD 3651 b scores 30 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 4 points would lift it into a rarer tier.

That score comes from 4 science badges — Confirmed exoplanet, Gas giant, Eccentric orbit and Its star is visible to the naked eye — 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.