Putting the planets where they are tonight…

Every planet, moon, dwarf planet and spacecraft here is drawn where it really is right now, worked out from NASA JPL orbit data. Run time forwards or backwards with the bar at the bottom.

The Sun and planets

  • Sun
  • Mercury
  • Venus
  • Earth
  • Mars
  • Jupiter
  • Saturn
  • Uranus
  • Neptune

Dwarf planets

  • Ceres
  • Pluto
  • Haumea
  • Makemake
  • Eris

Moons

  • Moon
  • Phobos
  • Deimos
  • Io
  • Europa
  • Ganymede
  • Callisto
  • Mimas
  • Enceladus
  • Tethys
  • Dione
  • Rhea
  • Titan
  • Iapetus
  • Miranda
  • Ariel
  • Umbriel
  • Titania
  • Oberon
  • Triton
  • Charon

Belts

  • Asteroid Belt
  • Kuiper Belt

Spacecraft

  • Voyager 1
  • Voyager 2
  • New Horizons
  • Pioneer 10
  • Pioneer 11

Fall inside

  • Inside the Sun
  • Inside Mercury
  • Inside Venus
  • Inside Earth
  • Inside Mars
  • Inside Jupiter
  • Inside Saturn
  • Inside Uranus
  • Inside Neptune
  • Inside the Moon
  • Inside Europa
  • Inside Titan
Right now · live
A moon of Saturn ↑

Iapetus

Half coal-dark, half snow-white, with a mountain ridge round its waist.

When Giovanni Cassini found Iapetus in 1671, he noticed he could only see it on one side of Saturn.

The reason: one half of Iapetus is as dark as coal, the other as bright as snow. Scientists think dust from farther out darkens the leading side, and the ice there then warms and drifts away to the bright side.

A ridge of mountains runs around its equator, up to 20 km high in places, making it look like a walnut.

Its orbit is tilted, so from Iapetus you'd see Saturn's rings from above, not edge-on.

If you stood here

Depending on where you stood, the ground would be black or white. Saturn would look about four times wider than the full Moon from Earth.

The numbers

Width
1,469 km
Goes round Saturn
every 79 days
One day
The same: it always shows Saturn one face
Temperature
−143 °C on the dark side · −183 °C on the bright
70 kg on Earth weighs
2 kg here
Quick answers+

How big is Iapetus?

Iapetus is 1,469 km wide, about 12% of Earth's width.

How long does Iapetus take to go round Saturn?

Iapetus goes once round Saturn every 79 days. It spins once in the same time, so it always shows Saturn the same face.

How hot or cold is Iapetus?

−143 °C on the dark side, and −183 °C on the bright.

What is the gravity like on Iapetus?

Gravity is 0.223 m/s², 2% of Earth's. Someone who weighs 70 kg on Earth would weigh 2 kg there.