Star Swap

Swap the central star and watch real Kepler's-law physics change every planet's orbital speed instantly. Planets that fall inside the Roche limit get torn apart.

Central Object

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Sun-like Star

Mass: 1 M☉

Radius: 696000 km

Density: 1408 kg/m³

Luminosity: 1.00 L☉

Habitable zone: 0.95–1.37 AU

Planet Fates

Mercury408KSafe

Venus301KSafe

EarthHZ255KSafe

Mars207KSafe

Jupiter112KSafe

Saturn82KSafe

Uranus58KSafe

Neptune47KSafe

A normal main-sequence star fusing hydrogen into helium in its core. Planets orbit stably at their real-world distances since density and gravity are balanced as expected.