How does the interstellar medium collapse into stars in the presence of strong magnetic fields? New SOFIA far-infrared polarimetric observations reveal that gravity drags weakened magnetic fields, allowing the streaming of the magnetized gas along filaments that ultimately feed the star-forming region.

See Pillai et al.

The interstellar medium is composed of vast flows of gas and dust at densities that vary across many orders of magnitude. Here, Henshaw et al. measure velocities across hugely different distances, finding that velocity and density fluctuations are ubiquitous and connected across spatial scales and galactic environments.

See Henshaw et al.

The MAVEN spacecraft has mapped the whole system of electric currents surrounding Mars, which does not have an intrinsic magnetic field. There are unexpected features and striking differences in comparison to the current systems of magnetized planets like the Earth.

See Ramstad et al.

The presence of cold gas in the centre of some galaxy clusters raises questions about its origin. Through a radiation-hydrodynamic simulation of active galactic nucleus feedback in such a cluster, Qiu et al. show that initially hot outflows can cool radiatively, forming extended filaments that resemble those observed.

See Qiu et al.

The Dawn spacecraft observed Occator crater and its faculae at unprecedented resolution before ending its mission in October 2018. The data reveal an active world with a salty internal ocean interspersed with rock particles.

See Nathues et al.

3D magnetohydrodynamic simulations show that the heliosphere is not elongated and comet-like, but rather has a smaller crescent-like shape. The model agrees with observations obtained by Cassini, New Horizons, and the two Voyager spacecraft.

See Opher et al..

A small blob of material (one of those shown in red in this image) is a pristine remnant of the progenitor of the Cassiopeia A supernova, since it currently sits outside of the supernova shock wave. According to spectral analysis, this clump originated near the helium core of what was likely to be a blue supergiant.

See Koo et al.

A CubeSat hosting the PolarLight payload has made it possible to conduct polarimetry in the soft X-ray band from space, more than 40 years after this opportunity was last available to astronomers. Hua Feng and colleagues observed the Crab, fortunately catching the pulsar during a glitch.

See Feng et al.

This issue celebrates the legacy of the Spitzer Space Telescope mission, one of NASA’s Great Observatories, which came to a conclusion earlier this year. Spitzer’s infrared view of the Universe brought many great discoveries across the breadth of astronomy and planetary science, summarised here in a variety of Reviews and other articles.

See Spitzer Insight Collection https://www.nature.com/collections/cabbfadjgg/

This is the gravitational waveform from a general relativistic simulation of a binary black hole system. Binary black holes are now routinely detected by ground gravitational wave detectors. Space missions such as LISA will be able to monitor the evolution of these binaries years before they merge, allowing multi-frequency gravitational wave astronomy.

See Jani et al.

Blazars are some of the most energetic cosmic accelerators. This artistic rendering of their multiwavelength emission was created by secondary school students from Padova, Italy. The blazar jet was drawn with coloured pencils on black cardboard. The background stars were made with a reversed-colour photograph of nails driven into a plywood board.

See Biteau et al.

Fully coupled atmosphere-ocean-ice model simulations show that for tidally locked terrestrial planets around low-mass stars a transition from an eyeball-like climate with open ocean to a globally ice-covered snowball climate is possible. This process is driven by sea-ice flows.

See Yang et al.