Saturn and its broad rings in a natural-colour mosaic photographed by the Cassini spacecraft.

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Preparing the 3D view

Preparing lighting and the first complete frame…

Model scale

Orbits use one AU scale. bodies enlarged for visibility.

Earth: mean radius 6,371.008 km · a = 1.000 AU · period 1.000 years. Model year 0.800; distance 0.995 AU.

How to read these results

All planets begin at perihelion in this model. Press T to show physical radii at the orbital scale, or choose Inner / all orbits to examine the inner system.

Solar system

Compare the sizes and orbital periods of planets, and explain why planets farther from the Sun take longer to orbit.

Drag to rotate. Hold Ctrl and scroll to zoom, or pinch on a touch screen.

Why it happens

Planets differ enormously in size, orbital distance and period. Kepler’s laws connect distance with orbital period and explain why a planet moves faster near the Sun than farther away.

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Cassini, 6 October 2004: a natural-colour mosaic of Saturn and its rings. The rings are a thin disc of orbiting particles.

Try a comparison

Show all eight, then switch to physical scale and compare planet radii with the distances between their orbits.

Reading the result

The orbital experiment uses fixed reference elements and chosen starting positions, so it does not show the planets’ locations today.

A common misunderstanding

A picture comparing planet sizes also shows their correct spacing.

Planet radii and orbital distances differ across such large ranges that many illustrations use separate scales for them. A size-comparison view may preserve relative radii while arranging planets close together. Check the stated scale before using a displayed gap as a physical distance.

Cases

Exam language

Orbital period

The time taken for a body to complete one orbit around another body. Planets farther from the Sun generally have longer periods: Mercury takes about 88 days and Neptune about 165 years. This differs from the body’s rotation period.

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Cassini's natural-colour mosaic of Saturn and its rings. Orbital period depends on orbital size and the central mass. This image shows one system; it does not preserve the scale of distances across the whole Solar System.

Terrestrial planet

A planet with a predominantly rocky composition and a solid surface, such as Mercury, Venus, Earth or Mars. The category describes composition rather than habitability. These planets differ greatly in atmosphere, temperature and geological activity.

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Apollo 17's Blue Marble, 7 December 1972. Earth's axial tilt changes the angle and duration of sunlight over the year.

Gas giant

A large planet made mainly of hydrogen and helium, such as Jupiter or Saturn. These planets have deep atmospheres above increasingly dense interiors and lack a solid surface like Earth’s. Their visible bands and storms occur within the atmosphere.

Ice giant

Uranus or Neptune: a giant planet with a hydrogen–helium atmosphere and an interior enriched in substances such as water, ammonia and methane. These are not simply layers of ordinary frozen ice.

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NASA/JPL Voyager 2 image assembled from green and orange filter observations in August 1989. Neptune is an ice giant; its displayed deep blue is enhanced relative to its natural appearance.

Astronomical unit

A defined length of 149,597,870,700 m, approximately Earth's mean distance from the Sun; abbreviated au or AU.

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SDO's time sequence of the 2012 Venus transit. Such alignments require the planet to be near an orbital node. Historical transit timing helped determine the Earth–Sun distance, now represented by the precisely defined astronomical unit.

Kepler’s third law

For bodies orbiting the same dominant mass, orbital period squared is proportional to the cube of the semi-major axis: T² ∝ a³.

True scale

A view in which stated lengths use the same scale factor. If a display still exaggerates a feature or compresses distances, it must identify that exception explicitly.

Planetary ring

A collection of particles orbiting a planet, ranging from fine dust to larger fragments. Saturn's rings consist mainly of water ice.

Process0.40ViewSelected planetModel duration2 yr