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Rare exoplanet 48 EP

HD 20868 b

RA 50.1794° · Dec -33.7297° · exoplanet

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Score breakdown

· 4 badges
48 pts · Rare
Rare 50 pts → Epic
  • In the habitable zone +30
  • Eccentric orbit +9
  • Confirmed exoplanet +5
  • Gas giant +4
Total score 48

2 more points to reach Epic.

Badges

  • Confirmed exoplanet · +5
  • In the habitable zone · +30
  • Gas giant · +4
  • Eccentric orbit · +9

Trivia

What makes it special

  • Goldilocks zone. Sits where it's neither too hot nor too cold — liquid water could exist on a surface here.

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.
  • What the zone means. The habitable zone is only about temperature: it is the band where liquid water could survive on a surface. It is a promising address, not evidence of anything living.

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 9.9 you'll want a small backyard telescope.
  • 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 November — that's when to go looking.

Properties

density gcc
0.849
diameter km
174759.94
discovery facility
La Silla Observatory
discovery method
Radial Velocity
discovery year
2008
dist ly
155.6491
eccentricity
0.75
eq temp k
207.11
habitable zone
yes
host star teff
4802
insolation
0.3278
mag
9.92
mass earth
397.2875
name
HD 20868 b
orbital period days
380.85
radius earth
13.7
semi major au
0.95
spect
K3/4 IV
sys num planets
1
sys num stars
1

About HD 20868 b

HD 20868 b is a rare exoplanet. It lies about 155.6 light-years from Earth, shines at apparent magnitude 9.92, has spectral type K3/4 IV and has an equilibrium temperature near 207 K.

Sits where it's neither too hot nor too cold — liquid water could exist on a surface here.

How to see it

At apparent magnitude 9.92, a small backyard telescope will bring it into view.

Like any astronomical target, HD 20868 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 20868 b is a rare exoplanet

HD 20868 b scores 48 points on Spacedle's rarity scale, which places it in the rare tier. Another 2 points would lift it into a rarer tier.

That score comes from 4 science badges — Confirmed exoplanet, In the habitable zone, Gas giant and Eccentric orbit — 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.