Deimos is so small you could almost jump right off it into space!
Tiny lumpy outer moon of Mars, likely a captured asteroid.
Moon: Orbits a planet rather than the star. Every kind of thing there is →
No. No telescope on Earth will show you this one; it is here to be understood, not seen. It is here because it is worth knowing about — and because leaving it out would make the sky look emptier than it is.
Deimos is even smaller than Phobos -- you could jog across it. In weight, about 1.5 trillion tonnes. Its day: tidally locked; same as its orbital period, 30.3 hours.
| Across | 12 km |
|---|---|
| Distance from the planet it orbits | 23 463 km |
| Once round its orbit | 30.3 hours |
| One spin | 30.3 hours |
Nobody flew a tape measure out there. Every number on this page was worked out from the ground:
Not this one. But the sky over your head is full of ones you can see, and the Planetarium knows which.