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Entering orbit…
Habitability
10/ 100
Uninhabitable
TOI-2018 c rendered in TerraForge from its measured mass, orbit and star

TOI-2018 c

Also written TOI-2018c, TOI 2018c, TOI 2018 c

Rocky Terrestrial91 light years awayFound 2023
Mass
3.59 × Earth
Radius
1.54 × Earth
Gravity
1.51 g
Surface (est.)
580 K
Year
11.2 days
From Earth
91.3 ly
Mass
3.59 × Earth
Radius
1.54 × Earth
Gravity
1.51 g
Surface (est.)
580 K
Year
11.2 days
From Earth
91.3 ly

TOI-2018 system

Type
K-type (Orange)
Spectral type
K8V
Temperature
4,174 K
Radius
0.62 ☉
Mass
0.57 ☉
Planets
2
Luminosity
0.105 ☉

Published by the Extrasolar Planets Encyclopaedia. This world’s temperature and habitability score are computed from its star’s published radius and temperature.

TOI-2018 c0.081 AUYou are here3.6 M⊕
Habitable zone

Star and planets drawn to scale: the star is 44 times as wide as TOI-2018 c, so only its edge is in view. Orbits spaced as in the star system view.

exoplanet.euListed by the Extrasolar Planets Encyclopaedia; not yet in NASA's confirmed catalogue.View on exoplanet.eu

Rocky Terrestrial, likely · its density could also fit a sub-Neptune

TOI-2018 c, from the Extrasolar Planets Encyclopaedia (found 2023). Measured: 3.59 Earth masses, 0.0814 AU, a 4174 K K-type star. Composition inferred from a measured bulk density of 0.98x Earth's at this size, suggesting roughly 16% water/ice by mass, with a day locked to its 11.2-day year, as anything orbiting this close would be.

Surface. Rocky surface with impact craters, possible volcanic features

Rocky Terrestrial
Life unlikely — too hot for liquid waterHigh Activity
TOI-2018 c is dominated by silicate (21.4%) and iron (11.0%) content, forming a rocky terrestrial body.
Rocky terrestrial planets are primarily composed of silicate rocks and metals. They're the most common type of small planet in the universe.
Classification Criteria:
✓ Silicon: 21.4% + Iron: 11.0% + Magnesium: 3.0%✓ Mass: 3.6x Earth (terrestrial range)

Reading TOI-2018 c’s atmosphere

Dominant elements: O, Si, H, Fe, N, CThis is what a telescope would measure while TOI-2018 c crosses in front of its star: starlight passes through the atmosphere and spreads into a rainbow band. Each dark line marks a wavelength the atmosphere absorbed.Every element absorbs its own signature wavelengths — hydrogen always darkens the same two spots, calcium another pair, and so on. Astronomers match the lines in a real spectrum against a library of these signatures to say what an atmosphere is made of, light-years away, without ever visiting. A deeper line generally means more of that element is present.TOI-2018 c sits about 91 light-years away, found by the transit method. Most catalogued distances trace back to parallax: as Earth orbits the Sun, a nearby star appears to shift very slightly against the distant background stars, and the size of that shift gives its distance directly.
Further reading
ExoplanetsSara Seager (editor)The field's standard reference: how planets are found, how they form, and what their atmospheres are made of.The Planet FactoryElizabeth TaskerHow planets are made, and why so few of them come out like Earth.The Little Book of ExoplanetsJoshua WinnHow these worlds are found, and what a measurement can honestly tell us.Exoplanets: Diamond Worlds, Super Earths, Pulsar PlanetsMichael Summers & James TrefilThe strange end of the catalogue — carbon worlds, molten rock, planets orbiting dead stars.
As an Amazon Associate I earn from qualifying purchases — if you buy through these links, TerraForge may receive a small commission at no extra cost to you.
Habitability ScoreUninhabitable
10
Contributing Factors
temperature6
Extremely hot - hostile to known life forms
atmosphere42

Thin CO₂ and nitrogen atmosphere

Nitrogen atmosphere provides protection but not breathable (partially stripped by slow rotation)
water23
Abundant water - boiling away, little would be retained
magnetic Field30
No magnetic field - vulnerable to solar radiation
geology90
Active geology recycles nutrients and drives carbon cycle
Organic Chemistry80
Core organic elements (CHNO) present
rotation30
Very slow rotation - days and nights each last several Earth days, bringing extreme temperature swings

Physical Properties

Mass
3.59x Earth (2.14e+25 kg)
Radius
1.53x Earth (9,755 km)
This planet: 1.53× Earth radiusEarth: 1× (baseline)
Surface Gravity
1.53x Earth (15.0 m/s²)
Surface Temperature
580 K (307 °C / 584 °F)
Rotation Period
268.8 hours/day (slower than Earth)
This planet: 269 h/dayEarth: 24 h/day

Elemental Composition

A dark ringed planet hanging over the horizon of a rocky moon, its rings lit by a distant sun

New: Stand on Your Moons 🌒

A planet's surface view isn't the only ground any more. Press the surface button on a planet with moons and it asks where to stand: the planet itself, or any moon still in orbit, each tagged with what it became — ocean, ice, carbon, volcanic. Every moon gets its own ground and sky from its own physics: airless rock under a black sky, ice cracked by geysers over a hidden sea, sulfur plains shaking with eruptions, or orange haze you can't see the sun through. And hanging over the horizon, there's the planet you built.

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