Offworld — Interactive exoplanet atlas

The atlas’s choices

This atlas owns its representational choices. Here are the main scientific decisions and how they were made.

The distances between stars are real — computed from each system’s coordinates, converted to galactic coordinates with Earth at the origin. Sagittarius A* sits at its true distance (~26,000 light-years). The size of objects, however, is not to scale: otherwise stars would be invisible points separated by void. The concentric rings (500 to 5,000 parsecs) give the real scale of distances.

Showing everything to true scale is impossible: a star is hundreds of times the size of a tight orbit. So we use two decoupled scales — star size is symbolic, set by its spectral type (a blue giant is larger than a red dwarf), and orbital distances follow a logarithmic scale that keeps the innermost planet visible next to the star. The habitable zone is always in frame.

When a planet’s distance to its star has not been measured — more than a third of the catalog — it is given a fictional position, and its orbit is drawn dotted: the planet exists, but its distance is invented. The frost line and the habitable zone are computed from the star — so they are real. An element beyond the frame is drawn with wide dashes prefixed by an arrow: it is a direction, not a distance.

About 12% of systems have no measured stellar temperature. Rather than inventing a type for them, we show them as a neutral gray sun and name them “Unknown star”. It’s a principle we apply throughout the atlas: show uncertainty rather than hide it.

No photo of an exoplanet exists: every surface is an artist’s impression, drawn from the planet’s scientific type — ocean world, gas giant, lava world… This type is inferred first from the measured radius, otherwise from the mass. When neither settles it, the planet stays gray (“unknown type”): the name reflects what the measurement suggests, the image shows only what it can assert. The thresholds draw on the scientific literature (Fulton 2017, Rogers 2015, Kopparapu 2013).

The temperatures shown are equilibrium temperatures, and the source catalog computes them without albedo — as if the planet reflected none of its star’s light. In this dataset an Earth analog therefore reads ~279 K, not the ~255 K you’d get with Earth’s real reflectivity (and not its 288 K surface temperature either, warmed by the atmosphere). It’s not an error: every threshold in the classification sits on this same scale, so the planets stay comparable to one another. Read the numbers as a relative ladder — hotter, colder — rather than a literal “what it feels like on the ground”.

Color key

Sol

Exoplanetary system

Planet in the habitable zone

Sagittarius A*