Didymos compared to Earth

Rocky near-Earth asteroid orbited by its moon Dimorphos; target of NASA’s DART mission.

Can you see it?

No small telescope will show you this one; it is here to be understood, not spotted.

Didymos is roughly 1/46 as wide as Mount Etna.

Didymos orbits on average about one and two thirds times as far from the Sun as Earth does.

Didymos takes about 2.1 Earth years to go once round the Sun.

Didymos turns round once in about 2.3 hours; Earth takes about 24 hours. And Didymos spins backwards.

Why it stands out: It has a moon of its own, as about one near-Earth asteroid in six of its size does — little Dimorphos circles it every 11.37 hours (11.92 hours before DART struck it).
A near-Earth asteroid: Its orbit comes close to Earth’s own, which is why it was reachable enough to be chosen for the first test of whether we could nudge one off course.

The numbers

Mean diameter	761 m
Distance from the Sun	1.643 AU on average, from 1.013 to 2.272 AU · sunlight takes 13 minutes 40 seconds at its average distance
Once round its orbit	2.105 Earth years
Sunrise to sunrise	2.259 hours — and it turns the other way, so the Sun there rises in the west