Epic exoplanet 51 EP

HD 181720 b

RA 290.7212° · Dec -32.9208° · exoplanet

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Score breakdown

· 4 badges

51 pts · Epic

Epic 68 pts → Anomaly

In the habitable zone +30
Puffy low-density world +12
Confirmed exoplanet +5
Gas giant +4

Total score 51

17 more points to reach Anomaly.

Badges

Confirmed exoplanet · +5
In the habitable zone · +30
Gas giant · +4
Puffy low-density world · +12

Trivia

What makes it special

Goldilocks zone. Sits where it's neither too hot nor too cold — liquid water could exist.
Cotton-candy planet. So low-density it would float on water.

Could we get there?

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

Getting there

Aboard Voyager 1. ≈ 3.5 million years at Voyager 1's speed (17 km/s).
Fastest probe ever. ≈ 306.6 thousand years even at the Parker Solar Probe's 192 km/s.
At 10% light speed. ≈ 1964 years in a starship at a tenth of light speed.
Distance. 196 light-years from Earth.

Look-back time

Look-back time. The light you'd see left around the year 1830.

Saying hello

Say hello. A radio message and its reply would take 393 years round-trip.

Standing on it

A year here. A full year lasts about 2.6 Earth years.

By the numbers

Size. About 14× the width of Earth.
Volume. About 2744 Earths could fit inside it.
Mass. Roughly 127× Earth's mass — about 0.4 Jupiters.
Your weight. You'd weigh about 0.6× your Earth weight standing here.
Density. Less dense than water — drop it in a big enough ocean and it would float.
Temperature. A frigid -24°C — colder than dry ice.

How we found it

Discovery. Found by La Silla Observatory using the radial velocity method.

Properties

density gcc: 0.255
discovery facility: La Silla Observatory
discovery method: Radial Velocity
dist ly: 196.3609
eccentricity: 0.26
eq temp k: 249.06
habitable zone: yes
insolation: 0.5671
mass earth: 127.132
name: HD 181720 b
orbital period days: 956
radius earth: 14
sys num planets: 1

About HD 181720 b

HD 181720 b is an epic exoplanet. It lies about 196.4 light-years from Earth, has an equilibrium temperature near 249 K, spans roughly 14 Earth radii and weighs about 127.13 Earth masses.

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

How to see it

Like any astronomical target, HD 181720 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 181720 b is an epic exoplanet

HD 181720 b scores 51 points on Spacedle's rarity scale, which places it in the epic tier. Another 17 points would lift it into a rarer tier.

That score comes from 4 science badges — Confirmed exoplanet, In the habitable zone, Gas giant and Puffy low-density world — 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.