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A sense of scale.

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Earth12,742 km
GJ 504 b≈131,500 km · estimated
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Planet profile

GJ 504 b

A pink world, far from home.

10.3×Earth’s diameter
estimated
≈57light-years
from Earth
≈291°Ceffective temperature
model estimate
About the rotation

In this animation, GJ 504 b turns 2.4× as fast as Earth, inspired by Jupiter’s roughly 10-hour rotation. Both speeds are accelerated for viewing. This is an artistic assumption; GJ 504 b’s actual rotation period has not been confirmed in the sources used here.

NASA · Jupiter and Earth rotation ↗
A world of magenta

NASA described its expected appearance as dark cherry-blossom pink, glowing with heat left from formation. The detailed bands here are artwork.

NASA · the pink appearance ↗
Seen with infrared eyes

Discovered in 2013 using the Subaru Telescope in Hawaiʻi. Astronomers isolated its infrared light from the glare of its Sun-like host star.

NASA · discovery ↗
Clouds with a different recipe

A 2026 JWST study finds evidence for salt clouds. Its atmospheric model favors potassium-chloride clouds, with zinc sulfide included in the adopted model.

Baburaj et al. 2026 · clouds ↗
Warm, even far from its star

The 2026 study estimates an effective temperature of 564 ± 4 K — about 291°C. This describes its emitted heat, not a solid surface temperature.

Baburaj et al. 2026 · temperature ↗
A very wide companion

Its discovery projected separation was about 43.5 AU: over 43 times the Earth–Sun distance. This is a sky-projected separation, not a precisely measured orbital radius.

NASA · separation ↗
The name hides a debate

“Pink planet” is the familiar nickname. Its mass and classification remain model-dependent; newer research favors a much heavier companion in the brown-dwarf mass range.

Baburaj et al. 2026 · mass and age ↗
View settings
Explore the original models ↗

Sizes stay fixed; only the shared camera moves. Spacing and rotation speed are illustrative. The ruler marks Earth diameters. Pink cloud bands are an artistic interpretation, not a resolved photograph.

Sources & credits
The numbers, uncertainty & sources

We adopt the 2026 JWST/NIRSpec atmospheric-model radius of 0.92 ± 0.02 Jupiter radii from Baburaj et al., sections 5.5 and 6.1. It is an inference from a model, not a directly measured disk. The quoted uncertainty does not capture every difference between models.

Using 1 Jupiter radius = 71,492 km and Earth’s mean radius = 6,371 km: GJ 504 b’s diameter is approximately 131,500 ± 2,900 km; the diameter ratio is 10.32 ± 0.22. For idealized spheres, the volume ratio is the cube of the diameter ratio: approximately 1,100 Earth volumes. This is volume equivalence, not a count of tightly packed Earth-sized spheres.

The NASA Exoplanet Archive currently lists the earlier Mâlin et al. (2025) radius of 1.08 (+0.04/−0.03) Jupiter radii, or about 12.1 Earth radii. We use the newer spectroscopic estimate consistently throughout this comparison. Radius, mass and age remain uncertain; the 2026 study estimates a mass of 25.2 (+8.4/−6.0) Jupiter masses.

Distance journey: approximately 57 light-years, or 539 trillion km. Star scenery and travel speed are cinematic. NASA · light-years

The ending comparison uses a round trip of 2 AU: twice the average Earth–Sun distance. NASA/JPL · astronomical unit