Japanese scientists propose in the journal Nature Geoscience that a large asteroid struck the Moon in the remote past and created the geological feature known as Oceanus Procellarum (or in common speak, Ocean of Storms). This large basin has a flattened feature stretching 1800 miles and it is being suggested it came about as a result of a collision. Over time, subsequent asteroid and meteorite strikes have blurred he edges of the impact zone – see http://phys.org/print270928754.html
Meanwhile, the joy ride to the Vesta asteroid by the Dawn spacecraft has led to new ideas – or information led ideas. This story is at http://phys.org/print270922145.html … and once again it is cratering that has caused a stir. According to a paper published in the journal Nature (1.11.2012) the surface of Vesta has thrown up a mystery. Space weathering is caused by the impact of countless tiny meteorites, or dust from space striking orbiting bodies and the impact of the energetic particles that make up the solar wind. Normally, they produce a fine coating of metal nano-particles that builds up on soil grains over time, causing a dark colouration of the surface. Material buried beneath the surface, on the other hand, lacks the metallic coating, so when a large meteorite strikes and churns up the surface it causes brighter sub-surface material to be brought to the top and this can clearly be seen by instruments as quite different to the darker metallic stuff, pinpointing where the strike actually occurred. However, Vesta does not conform to this picture, derived from observation of the Moon and a few other asteroids. Surface soil does not contain the metallic nano-particles. The solar wind appears to be reacting in a different way to how it affects the Moon and other bodies in space. What is going on?