> ...arguably the first _powered_ flights were done by the sky cranes of Opportunity and Perseverance
Not the Apollo 11 lunar module? In contrast to the sky cranes it actually lifted off again.
Not the Apollo 11 lunar module? In contrast to the sky cranes it actually lifted off again.
Figuring out something that works well in Mars' thin (but still there) atmosphere, especially a helicopter, is really impressive. The celestial body classification is just a cherry on top.
Edit: Phantom 4 is 1.3 kg and blades are 45g
Also, Isaac Asimov considered the system a dual-planet system as the Moon's path around the sun is at no point convex nor retrograde.
1% is an arbitrary threshold and solar orbit is dependent on external circumstances rather than the Earth-Moon system itself.
> Earth-Moon centre of mass is inside Earth, so, it's
> obvious that the Moon is orbiting the Earth, not both
> orbiting something else.
I'd tend to say that separating them further would tend more towards planet-moon. Yet doing so moves the system's center of mass outside the larger body, so would actually push the system into the dual-planet definition by that criterion.
The barycentre of the Sun and Jupiter isn't inside of the Sun.. so does that mean Jupiter doesn't orbit the Sun?