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Entering orbit…
Habitability
8/ 100
Uninhabitable

TOI-1728 b

Gas GiantUninhabitable198 light years awayFound 2020

TOI-1728 b, from the NASA Exoplanet Archive (found 2020). Measured: 26.8 Earth masses, 0.0391 AU, a 3980 K K-type star. Composition inferred from a measured bulk density of 0.21x Earth's, which only hydrogen and helium can explain, with a day locked to its 3.5-day year, as anything orbiting this close would be.

Host star

TOI-1728

Type
K-type (Orange)
Spectral type
M0
Temperature
3,980 K
Radius
0.624 ☉
Mass
0.646 ☉
Known planets
1 (this one)
Luminosity
0.0880 ☉

Published by the NASA Exoplanet Archive. This world’s temperature and habitability score are computed from this star’s measured luminosity, not from a stand-in for its class.

Gas Giant

Magnetic FieldExtreme Activity
Why is this a Gas Giant?Your planet has 86.0% hydrogen and helium, combined with a mass of 26.8x Earth, which exceeds the gas giant threshold.
Gas giants form when massive cores capture enormous atmospheres of light gases. They typically form beyond the 'frost line' where volatiles can condense.
Classification Criteria:
✓ Hydrogen + Helium: 86.0% (>60% required)✓ Mass: 26.8x Earth (>10x required)
Further reading
Exoplanets: Diamond Worlds, Super Earths, Pulsar PlanetsMichael Summers & James TrefilThe strange end of the catalogue — carbon worlds, molten rock, planets orbiting dead stars.The Little Book of ExoplanetsJoshua WinnHow these worlds are found, and what a measurement can honestly tell us.Envisioning ExoplanetsMichael CarrollWhat these worlds might look like from the ground, painted from the same measurements this page renders.Imagined LifeJames Trefil & Michael SummersWhat could live on a world like this one: ice shells, supergravity, tidally locked twilight.
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Habitability ScoreUninhabitable
8
Contributing Factors
temperature5
Scorching - hot enough to melt lead, though rock stays solid; no chance for life
atmosphere30
Hydrogen-rich atmosphere typical of gas giants
water15
No solid surface — any water is locked in a supercritical mantle and hot ice, not oceans
magnetic Field100
Magnetic field provides radiation protection
geology40
Extreme volcanic activity may be hazardous
Organic Chemistry80
Core organic elements (CHNO) present
rotation65
Slow rotation - significant day/night temperature variations, but life can adapt

Physical Properties

Mass
26.80x Earth (1.60e+26 kg)
Radius
2.99x Earth (19,066 km)
This planet: 2.99× Earth radiusEarth: 1× (baseline)
Surface Gravity
2.99x Earth (29.4 m/s²)
Surface Temperature
768 K (494 °C / 922 °F)
Rotation Period
83.8 hours/day (slower than Earth)
This planet: 84 h/dayEarth: 24 h/day

Orbital Environment

Star Type
K-type (Orange)
Distance from Star
0.04 AU (5.85 million km)
Orbital Period
3 days
Time Dilation
Clocks run 8.4 seconds per year slower than deep space — about 11 minutes over a lifetime

Atmosphere

Hydrogen and helium dominated with trace methane and ammonia

Elemental Composition

H - Hydrogen
53.8%
He - Helium
32.3%
O - Oxygen
5.4%

Surface Characteristics

No solid surface - thick gaseous envelope with possible rocky core deep within
The TerraForge exoplanet catalog: 5,572 real exoplanets run through the simulation, with a search field and rendered worlds grouped by type

New: The Exoplanet Catalog 🔭

Every confirmed planet NASA has measured well enough to build — 5,572 of them — is now in here, and none of them arrived with a label. Their real mass, radius, orbit and star go through the same simulation that runs everything you make, and it decides what each one is: gas giant, lava world, ocean, ice. Sixteen come out Earth-like. Find TRAPPIST-1e, stand on its surface, and see what a red dwarf's light actually looks like from the ground.

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