Orbital Calculator

Planet

all fields stay in sync

Rules

UWP

Optional: sets the world size from its UWP

World size

Radius (km)

Rotation (hours)

= standard days

Mass (10²⁴ kg)

Gravity (G)

Density (g/cm³)

Parent body

Parent mass

Orbital distance

The star (or planet, for a moon) this world orbits. It sets the Hill sphere: how far out the world's gravity can hold a satellite against its parent's pull.

The formula

h = ∛( G · M · T² ⁄ 4π² ) − R

h: Altitude of the satellite above the surface
G: Gravitational constant, 6.674 × 10⁻¹¹
M: Mass of the planet
T: Rotation period of the planet
R: Radius of the planet

Earth's geosynchronous orbit sits at 35,786 km altitude, a semi-major axis of 42,164 km.

Synchronous altitude

planet and orbit to scale

Semi-major axis km from the planet's center

Orbital speed km/s

Escape velocity km/s from the surface

Δv to sync orbit km/s

Coverage ° lat poleward limit from one satellite

Equatorial ring satellites to see the whole equator

Light lag to orbit ms surface to satellite, one way

Hill sphere km

Sol system reference

Use loads a body into the calculator

Body	Mass 10²⁴ kg	Volume 10¹² km³	Radius km	Rotation hours	Sync altitude km	Semi-major axis km	Speed km/s	Stability	Action