Rosetta flyby of Asteroid Lutetia Options

[Paolo]

time to start a thread on one of the most interesting UMSF events of 2010...
Published thu on arXiv Ultraviolet and visible photometry of asteroid (21) Lutetia using the Hubble Space Telescope

[Explorer1]

I think a good rule of thumb would be: it's an atmosphere if the body it surrounds is more or less spherical. That's a good a reference point as any right? Lutetia is excluded, but Ceres and maybe Vesta wouldn't be.


I doubt Hyperion or Proteus will break that rule anytime soon...

[nprev]

I think a good rule of thumb would be: it's an atmosphere if the body it surrounds is more or less spherical.

Somebody please correct me if I'm wrong, but wouldn't a gravitationally-bound gaseous envelope (yep, intentionally avoiding the "A" word, here) be spherically distributed around a body's center of mass regardless of its gross shape? In fact, wouldn't it follow the contours of its Hill sphere?

There might be pronounced local variations if there were very significant asymmetries in a body's internal mass distribution, but they'd have to be really big mascons, almost certainly much, much larger than any you'd expect to find on an asteroid.