> That shape? Asteroids don't come in that shape. They just don't. We've got literally thousands of data points which say that doesn't happen. We don't actuall

> That shape? Asteroids don't come in that shape. They just don't. We've got literally thousands of data points which say that doesn't happen. We don't actually know its shape, we just have a light curve. Depending on its axis of rotation it could be between 10:1 and a far less remarkable 5:1. As to why the first one detected has a extreme shape, that's likely to be observational bias. Our ability to detect these objects is marginal. An elongated object has a higher ratio of surface area to volume, so is brighter for a given size. If Oumuamua was more circular we might not have picked it up. > And the whole changing-trajectories business? The possible trajectory change is evidence of a very low level of outgassing, which can't be directly detected. Oumuamua is an interesting object, it's great that we've finally detected an interstellar object. It's not quite what we were expecting and we're not sure if it's an asteroid or a dead comet nucleus. We were expecting volatile comets to be more common but one idea is that it lost its volatiles when its parent star became a red giant, and was ejected at that point. When the LSST goes online hopefully we'll pick up a lot more and get a better idea of what the interstellar population looks like. But frankly, it probably isn't very remarkable, its spectrum is very similar to a D-type asteroid.