330 miles... that seems so small, and it's so far away. It would be a truly haunting experience to stand on that surface and look at the faint pinprick of Sol.
I agree. Where do they draw the line at dwarf planet and asteroid and/or comet? The thing is so far away. Are they able to confirm it's not just a chunk of ice, and therefore comet in a nearly circular (for a comet) orbit?
I believe the threshold is whether it's large enough to have collapsed into a spheroid. Vesta is about the same size as they're estimating, and it's still too lumpy.