Among the many ideas proposed to explain the formation of our Solar system, one of the leading theories is the “Grand Tack”. This scenario suggests that, early in their formation, Jupiter and Saturn undertook a sweeping voyage, migrating from the outer Solar System to within the orbit of Mars. The two huge planets then entered an orbital resonance with each other, before their cosmic dance took them back out to their current positions. The model neatly explains, amongst other things, the current locations of Mars, the Asteroid Belt and the outer planets—which are hard to recreate in models assuming a more static Solar System.
Planets seem to occur all over the place in the universe. However, it is still unknown how they form. The growth of objects larger than meter size is difficult because objects of this size quickly fall into the central star. This Astrobite gives a small overview of the meter-size barrier as found by Stuart J. Weidenschilling in 1977.
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.
For years we have observed the compelling fluvial features on the Martian surface. How did they get there? Was there a large ocean? Check out the very first measurements of how much water once flowed on Mars 4.5 billion years ago.
Mercury is the smallest planet in the Solar System, but some of its properties are a big challenge to explain. Today’s Astrobite presents a solution to one of these issues: The darkening of Mercury is induced by a high abundance of carbon delivered by meteorites.
Our Solar System is just plain odd compared to other star systems across our galaxy. Once again the finger of blame points towards the gas giant Jupiter as the simulations in this paper show.