Exomoons and Planet Scatter

18 Mar 2018

Jovan sent in the link www.skyandtelescope.com/astronomy-news/exoplanets/the-fate-of-exomoons-w... ... and once again we are back into mainstream worlds in collision. The title is 'The Fate of Exomoons when Planets Scatter' - planets interacting with each other on rogue orbits are thought to be a common phenomenon of our early solar system and therefore by extrapolation, other star systems as well. After all there are a lot of exoplanets out there. What happens to the moons when planets interact with each other? Would they generate a population of free floating ecomoons. Yu Cian Hong of Cornell University (and his team) have found 80 to 90 per cent of exomoons are destabilised during scattering and do not survive in their original position or orbit. This leads to collisions with each other, collisions with planets and it also means moons can be captured by other planets (even in our solar system). Moons can even be ejected entirely from the solar system (or the various star systems out there in the universe), and come to that moons and planets can also be ejected. Lastly, some moons could even become new planets. As such there may well be a large population of exomoons free floating out in the universe at large - otherwise undetected at the moment.

Remaining on the theme of mainstream worlds in collision we have a similar story at https://phys.org/print440412457.html ... colossal impacts. Apparently, new research advocates a giant impact on Mars, 4 billion years ago. This is promoted in order to explain the iron elements on that planet (and on the Earth). Planets, we are assured, form as small dust grains stick together and agglomerate with other dust particles, leading to bigger and bigger bodies (such as planetesimals). These, in turn, collide with each other and are either gobbled up by the Sun or go on to form even bigger bodies, the planets. So, as impossible it may be for worlds to collide in the modern solar system (according to the Velikovsky debunkers) we have multiple collisions in the early solar system - from dust grains to lumps of rock to planetesimals and planets, collisions that take place over and over again. William sent in the link but the piece goes on to say planets continue to accrete even after forming - by capturing the leftover fragments. This is where the colossal collision comes in - a late accretion event. When accretion takes place iron, it is thought, migrates downwards into the innards of planets like the Earth, creating an iron core.