Orbitarius

Planet Size Comparison Tool

Most space images use creative framing — the Moon is huge over the horizon, Earth and Mars sit next to each other on the same page. The Orbitarius Comparison tool throws that out. Pick any combination of planets, moons, dwarf planets, asteroids, stars, or black holes and they line up side by side at true relative scale, in 3D, in your browser. The result is usually surprising.

What you can line up

The catalog mirrors the Solar System view but is open-ended — anything you would compare, you can compare here.

  • All eight major planets and the Sun, with real diameters in kilometers.
  • Earth's Moon plus the Galilean moons, Saturn's larger moons, Triton, Titania, Oberon, Umbriel, and Charon.
  • Dwarf planets Pluto, Ceres, Eris, Haumea, and Makemake.
  • Asteroids Vesta, Pallas, and 16 Psyche, rendered from real 3D models.
  • A main-sequence star catalog from M-dwarfs through hypergiants — R136a1, UY Scuti, Stephenson 2-18, VY Canis Majoris.
  • Black holes with adjustable Schwarzschild radius, from stellar-mass up to supermassive.

Why it matters

Numbers like 'Jupiter is 11 times Earth's diameter' have a hard time hitting home. Seeing Jupiter actually sitting next to Earth at 3D scale does the job in one second. The same goes for the gap between the largest moons and the smallest planets, or for the surreal jump from our Sun to a hypergiant like UY Scuti.

Controls

Add a body and the camera reframes to fit. Navigate forward and back between objects, pause the slow rotation, hide names for a cleaner shot, or set transparency on a body to see what is hidden behind it. Re-arrange the line however you want, then take a screenshot or use the built-in recording to share the view.

Frequently asked questions

Is the scale really one-to-one?
Yes. Diameters are real kilometers and the on-screen scale is consistent across every object in the line. The smallest body in the line determines how zoomed-in the view is.
Can I compare a custom black hole?
Yes — choose the black hole option from the catalog and set the Schwarzschild radius. It will scale relative to the rest of the line correctly.
What about stars way bigger than the Sun?
The catalog includes hypergiants like Stephenson 2-18 and UY Scuti. Add the Sun to the line first and you will see exactly why these stars are unsettling.