The galaxies in the early universe were much smaller than our Milky Way and churned out stars at a rapid pace. They grew larger through mergers with other dwarf galaxies to eventually build the magnificent spiral and elliptical galaxies we see around us today. But astronomers using the Hubble Space Telescope have looked at two small galaxies that were left off the star party list. For many billions of years Pisces A and Pisces B lived in a vast intergalactic wilderness that was devoid of gas, which fuels star formation. They got left out in the cold.
Heating of Jupiter’s upper atmosphere above the Great Red Spot
Nature 536, 7615 (2016). doi:10.1038/nature18940
Authors: J. O’Donoghue, L. Moore, T. S. Stallard & H. Melin
The temperatures of giant-planet upper atmospheres at mid- to low latitudes are measured to be hundreds of degrees warmer than simulations based on solar heating alone can explain. Modelling studies that focus on additional sources of heating have been unable to resolve this major discrepancy. Equatorward transport of energy from the hot auroral regions was expected to heat the low latitudes, but models have demonstrated that auroral energy is trapped at high latitudes, a consequence of the strong Coriolis forces on rapidly rotating planets. Wave heating, driven from below, represents another potential source of upper-atmospheric heating, though initial calculations have proven inconclusive for Jupiter, largely owing to a lack of observational constraints on wave parameters. Here we report that the upper atmosphere above Jupiter’s Great Red Spot—the largest storm in the Solar System—is hundreds of degrees hotter than anywhere else on the planet. This hotspot, by process of elimination, must be heated from below, and this detection is therefore strong evidence for coupling between Jupiter’s lower and upper atmospheres, probably the result of upwardly propagating acoustic or gravity waves.
Astronomy: Gentle birth of a comet
Nature 536, 7615 (2016). doi:10.1038/536128a
The comet 67P/Churyumov–Gerasimenko (pictured), which has been orbited by the Rosetta spacecraft since 2014, might date back to the primordial Solar System billions of years ago.A team led by Björn Davidsson at NASA's Jet Propulsion Laboratory in Pasadena, California, used instruments on the European