We recently reported the discovery of an unpublished manuscript by Albert Einstein in which he attempted a 'steady-state' model of the universe, i.e., a cosmic model in which the expanding universe remains essentially unchanged due to a continuous formation of matter from empty space. The manuscript was apparently written in early 1931, many years before the steady-state models of Fred Hoyle, Hermann Bondi and Thomas Gold. We compare Einstein's steady-state cosmology with that of Hoyle, Bondi and Gold and consider the reasons Einstein abandoned his model. The relevance of steady-state models for today's cosmology is briefly reviewed.
Two of the most reliable changes in the sky are the daily rising of the sun in the east and setting of the sun in the west. But if you lived on a couple of Pluto's moons you wouldn't know when the day would begin, or even what direction the sun would rise. That's because, unlike Earth's moon, at least two of Pluto's small moons, Hydra and Nix, are tumbling chaotically through space. Why? Because they orbit inside a dynamically shifting gravitational field caused by the system's two central bodies, Pluto and Charon, that are whirling around each other. The moons are also football shaped, and this contributes to the chaotic rotation.
Resonant interactions and chaotic rotation of Pluto’s small moons
Nature 522, 7554 (2015). doi:10.1038/nature14469
Authors: M. R. Showalter & D. P. Hamilton
Four small moons—Styx, Nix, Kerberos and Hydra—follow near-circular, near-equatorial orbits around the central ‘binary planet’ comprising Pluto and its large moon, Charon. New observational details of the system have emerged following the discoveries of Kerberos and Styx. Here we report that Styx, Nix and Hydra
Astronomy: Pluto leads the way in planet formation
Nature 522, 7554 (2015). doi:10.1038/522040a
Authors: Scott J. Kenyon
Images from the Hubble Space Telescope cast new light on the orbits, shapes and sizes of Pluto's small satellites. The analysis comes just before a planned reconnaissance by the first spacecraft to visit them. See Article p.45
Hawaii prunes Mauna Kea telescope hub
Nature 522, 7554 (2015). http://www.nature.com/doifinder/10.1038/522015a
Author: Alexandra Witze
Cultural fight over sacred mountain accelerates observatory closures.
Nature 522, 7554 (2015). doi:10.1038/522006b
The coming months promise to shed new light on the Solar System’s underworld.