Why do rocky planets in a given star system usually look relatively similar? A new theory developed by Konstantin Batygin, professor of planetary science at Caltech, along with Alessandro Morbidelli of the Observatoire de la Côte d'Azur in France, may explain. "With the increase in exoplanet observations over the past decade, it has become clear that the standard theory of planet formation needs to be revised, starting with the basics. We need a theory that can explain both the formation of terrestrial planets in our solar system and the formation of self-similar systems of super-Earths, many of which have…

When you think of the rocks that make up our home planet (but also all the other rocky planets in the solar system), you probably immediately think of the fact that olivine and orthopyroxene are the predominant minerals in the Earth's mantle. If not, you are probably not a geologist. I confess, I didn't know that either. But is this actually normal? Are all rocky planets in the universe composed primarily of these minerals? That's an important question, because other rock types absorb more water than Earth's rocks, for example, which would affect the development of oceans. Others melt…

In my upcoming novel "Andromeda: The Encounter," an Earth-sized planet is wandering lonely through space. Planets far from any star - how common are they? Apparently, this is not an uncommon phenomenon. Star systems can become dynamically unstable and eject single planets. This could have happened to our solar system in early times. That it is a normal sight is also shown by a research work of British scientists. They have discovered evidence of a mysterious population of such free-floating planets. The findings were published in the Monthly Notices of the Royal Astronomical Society. The study, led by Iain…