Compare Worlds
Put any objects side by side, with sizes drawn to true relative scale.
Phobos
Earth
Disc areas drawn to true relative diameter. Objects with no defined radius (spacecraft, nebulae) are omitted from the picture.
| Property | Phobos | Earth |
|---|---|---|
| Type | Moon | Planet |
| Radius | 11 km | 6,371 km |
| Surface gravity | 0.01 m/s² | 9.81 m/s² |
| Day (rotation) | 7.7 h | 23.9 h |
| Year (orbit) | 0.3 days | 365.2 days |
| Distance | About 225 million km from Earth on average (riding with… | You are here — 149.6 million km from the Sun |
| In one line | Mars's doomed potato moon is spiraling slowly toward destruction. | The only place in the universe where life is confirmed to exist. We call it home. |
“—” means the property doesn’t apply or isn’t defined for that object. Full sourced figures live on each object’s own page.