Solar System Explorer

Holds 99.86% of all the mass in the solar system.

One Mercury day lasts about 176 Earth days — longer than its year.

Hotter than Mercury thanks to a runaway greenhouse effect.

Only known world with liquid water on its surface.

Olympus Mons is the tallest volcano in the solar system at ~22 km.

More massive than every other planet combined, twice over.

Less dense than water — it would float in a big enough bathtub.

Rotates on its side — likely knocked over by a giant impact.

Winds reach 2,100 km/h — the fastest anywhere in the solar system.

Largest object in the asteroid belt and the only dwarf planet inside it.

Reclassified from planet to dwarf planet in 2006.

Spins once every 3.9 hours — so fast it is stretched into an egg shape.

Named after the creator god of Rapa Nui (Easter Island).

Slightly more massive than Pluto — its discovery triggered Pluto's demotion.

Drifting away from Earth by about 3.8 cm every year.

The most volcanically active body known — 400+ active volcanoes.

Likely hides a salty ocean with more water than all of Earth's.

Largest moon in the solar system — bigger than Mercury.

The only moon with a substantial atmosphere.

Shoots water-ice geysers 500 km into space from its south pole.

Orbits backwards — almost certainly a captured Kuiper Belt object.