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.
The existence of a conducting layer near the core/mantle boundary has profound implications for the operation of a dynamo in rocky exoplanets and for our ability to detect exoplanetary magnetic fields.
Detailed atmospheric models reveal that planets can be habitable much closer to their host star than previously thought, provided they have desert-like climates. This expanded definition of the habitable zone increases the number of planets that could support life by a factor of 2-3.
The number of known moons of Pluto has now reached five. What are they like, and how did they get there? Kenyon and Bromley use numerical simulations to answer these questions and determine what else New Horizons may find in 2015.
The asteroid Vesta has been scared by two giant impacts, dredging up material from deep below its surface. New simulations of the impacts allow us to trace where the material should end up and creates a conflict between theory and observation.
Some exoplanets seem to have walked directly out of the best science fiction movies. Taking these planets into example, the question of habitability seems like a joke. But what if we stopped looking at these extreme worlds and turned our eyes to their moons instead? Surely their moons are less extreme. And given that our own Jupiter hosts 67 moons, surely they’re more abundant. Can such extreme planets host habitable moons? The 36-page paper written by Heller and Barnes attempts to address this question.
I’ve got pretty bad eyesight. If I take off my glasses and look at the flowers on my window sill, they look like a fuzzy yellow blob. But with glasses, the petals and the patterns cast on them come into focus. This is how I felt when looking at the new observations of the debris disk around AU Mic. Putting on our ALMA glasses, the fuzzy debris disk around AU Mic is sharpening into something surprisingly consistent with our own Solar System.
Can we infer the presence of multiple planets by monitoring how a star’s brightness changes outside of planetary transit?
How long does planetary migration take? Crockett et al. look for the answer by searching for hot Jupiters around extremely young stars.
Astronomers recently announced the discovery of a short period Earth-mass planet in the Alpha Centauri system. Could Earth-mass planets exist in the habitable zones of binary stars?