Physical Size

A scroll-driven journey through the scale of the universe, from subatomic structures to the largest known cosmic systems.

MarsTerrestrial planet·6,779 km

VenusTerrestrial planet·12,104 km

EarthTerrestrial planet·12,742 km

NeptuneIce giant planet·49,528 km

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Planets

Venus

Venus is the second planet from the Sun and the closest planetary match to Earth in size, but its surface conditions are radically different. A dense carbon-dioxide atmosphere drives a runaway greenhouse effect that makes Venus hotter than Mercury, even though it orbits farther from the Sun.

Scale fact12,104 kmdiameter

Object class: Terrestrial planet
Mass: ~0.815 Earth masses
Host: Sun
Estimated age: ~4.5 billion years
Composition: Silicate rock, iron core, dense carbon-dioxide atmosphere
Temperature: ~737 K mean surface

Planets

Earth

Earth is the rocky planet on which we live and the most familiar anchor for planetary scale. It remains the only world known to host life, with long-lived surface oceans that have shaped both its geology and its atmosphere.

Scale fact12,742 kmdiameter

Object class: Terrestrial planet
Composition: Silicate rock and iron core
Temperature: ~288 K mean surface
Estimated age: ~4.54 billion years
Host: Sun

Planets

Neptune

Neptune is the outermost giant planet in the Solar System. It is the windiest world known, with methane-cloud systems racing through its atmosphere at speeds above 2,000 kilometers per hour.

Scale fact49,528 kmdiameter

Object class: Ice giant planet
Mass: ~17 Earth masses
Host: Sun
Estimated age: ~4.5 billion years
Composition: Hydrogen, helium, water-ammonia-methane ices
Temperature: ~59 K cloud tops