Roughly half of all planetary systems have planets much closer to their stars than Mercury is to our Sun. Can a system’s magnetic field during the stage of planet formation explain why half of all systems (including our own) do not have these planets when the other half do?
In July of this year (2015), NASA’s New Horizons mission will fly past Pluto and its moons. It will map the surface of the Plutonian system in unprecedented detail, revealing craters and other surface features for the first time. In preparation for the deluge of newly discovered craters, mountains, crevasses and other surface features, Mamajek et al. discuss a naming system for Pluto and its moons.
A new model explains Mercury’s major density with magnetism.
Mercury’s high density has been a longstanding puzzle in planetary science. Its density means that it must have a significantly higher iron abundance than Venus, Earth, Mars, or the asteroids, probably in the form of a large iron core. NASA’s MESSENGER mission has challenged many of the hypothesized ways to create an iron-rich Mercury; a new hypothesis is required.
Today, Mercury rotates only three times in two Mercury years. How did the planet get to this state? Was Mercury tidally locked in the past?