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Entering orbit…
Habitability
0/ 100
Uninhabitable
HD 219134 d rendered in TerraForge from its measured mass, orbit and star

HD 219134 d

Also written HD 219134d

Rocky Terrestrial21 light years awayFound 2015
Mass
16.20 × Earth
Radius
1.61 × Earth
Gravity
6.25 g
Surface (est.)
410 K
Year
46.9 days
From Earth
21.3 ly
Mass
16.20 × Earth
Radius
1.61 × Earth
Gravity
6.25 g
Surface (est.)
410 K
Year
46.9 days
From Earth
21.3 ly

HD 219134 system

Type
K-type (Orange)
Spectral type
K3 V
Temperature
4,699 K
Radius
0.778 ☉
Mass
0.81 ☉
Planets
7
Luminosity
0.265 ☉

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.

HD 219134 b0.039 AU4.7 M⊕
HD 219134 c0.065 AU4.4 M⊕
HD 219134 f0.15 AU7.3 M⊕
HD 219134 d0.24 AUYou are here16 M⊕
HD 219134 g0.38 AU11 M⊕
HD 219134 e2.56 AU71 M⊕
HD 219134 h3.11 AU108 M⊕
Habitable zone

Star and planets drawn to scale: the star is 53 times as wide as HD 219134 d, so only its edge is in view. Orbits spaced as in the star system view.

Estimated: this planet doesn't transit its star, so its size is inferred, not measured

HD 219134 d is a planet whose mass depends on whom you ask. It orbits HD 219134, an orange dwarf star about 21 light-years away, every 46.7 days, and was found in 2015 by two teams independently, both measuring the slight back-and-forth motion its gravity gives the star.

Surface. Rocky surface with impact craters, possible volcanic features

Rocky Terrestrial
Magnetic FieldExtreme Activity
HD 219134 d is dominated by silicate (36.6%) and iron (24.4%) 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: 36.6% + Iron: 24.4% + Magnesium: 12.2%✓ Mass: 16.2x Earth (terrestrial range)

Reading HD 219134 d’s atmosphere

Dominant elements: Si, Fe, Mg, Ni, S, AlThis is what a telescope would measure while HD 219134 d 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.HD 219134 d sits about 21 light-years away, found by the radial velocity 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
0
Contributing Factors
temperature13
Extremely hot - hostile to known life forms
atmosphere10

Minimal or none

No atmosphere - exposed to radiation and temperature extremes
water0
No water - the recipe has no hydrogen and oxygen to form it
magnetic Field100
Magnetic field provides radiation protection
geology40
Extreme volcanic activity may be hazardous
Organic Chemistry20
Limited organic chemistry potential
rotation100
Optimal rotation period - balanced day/night cycle, moderate weather, and good heat distribution

Physical Properties

Mass
16.20x Earth (9.67e+25 kg)
Radius
2.53x Earth (16,121 km)
This planet: 2.53× Earth radiusEarth: 1× (baseline)
Surface Gravity
2.53x Earth (24.8 m/s²)
Surface Temperature
410 K (137 °C / 278 °F)
Rotation Period
24.0 hours/day
This planet: 24 h/dayEarth: 24 h/day

Elemental Composition

How TerraForge built this world

HD 219134 d, from the NASA Exoplanet Archive (found 2015). Measured: 16.2 Earth masses, 0.237 AU, a 4699 K K-type star. Composition inferred from a measured bulk density of 3.88x Earth's, far too high for silicates alone — an iron-rich world, with an assumed 24-hour day — rotation cannot be measured for exoplanets.

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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