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Rare exoplanet 47 EP

HD 100777 b

RA 173.9646° · Dec -4.7555° · exoplanet

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Score breakdown

· 4 badges
47 pts · Rare
Rare 50 pts → Epic
  • In the habitable zone +30
  • Orbits a Sun-like star +8
  • Confirmed exoplanet +5
  • Gas giant +4
Total score 47

3 more points to reach Epic.

Badges

  • Confirmed exoplanet · +5
  • In the habitable zone · +30
  • Gas giant · +4
  • Orbits a Sun-like star · +8

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 8.4 it is just past naked-eye reach — ordinary binoculars will pull it in.
  • Seen from everywhere. It sits almost on the celestial equator, so it can be seen from essentially anywhere on Earth.
  • Best time of year. It stands highest in the middle of the night around March — that's when to go looking.

Properties

density gcc
0.835
diameter km
174759.94
discovery facility
La Silla Observatory
discovery method
Radial Velocity
discovery year
2007
dist ly
161.5568
eccentricity
0.38
eq temp k
264.28
habitable zone
yes
host star teff
5533
inclination
90
insolation
0.9345
mag
8.42
mass earth
390.9289
name
HD 100777 b
orbital period days
383
radius earth
13.7
semi major au
1.06
spect
G8 V
sys num planets
1
sys num stars
1

Nearby objects

About HD 100777 b

HD 100777 b is a rare exoplanet. It lies about 161.6 light-years from Earth, shines at apparent magnitude 8.42, has spectral type G8 V and has an equilibrium temperature near 264 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 8.42, it is an easy target for binoculars.

Like any astronomical target, HD 100777 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 100777 b is a rare exoplanet

HD 100777 b scores 47 points on Spacedle's rarity scale, which places it in the rare tier. Another 3 points would lift it into a rarer tier.

That score comes from 4 science badges — Confirmed exoplanet, In the habitable zone, Gas giant and Orbits a Sun-like star — 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.