Massive stars, those over ten times heavier than our Sun, are the conduits of most elements of the periodic table and drive the morphological and chemical makeup of their host galaxies. Yet the origin of the most luminous and hottest stars among them, called 'blue supergiants', has been debated for many decades. Blue supergiants are strange stars. First, they are observed in large numbers, despite conventional stellar physics expecting them to live only briefly. Second, they are typically found alone, despite most massive stars being born with companions. Third, the majority of them harbour

The development of the latest generation of Imaging Atmospheric Cherenkov Telescopes (IACTs) over recent decades has led to the discovery of new extreme astrophysical phenomena in the very-high-energy (VHE, E > 100 GeV) gamma-ray regime. Time-domain and multi-messenger astronomy are inevitably connected to the physics of transient VHE emitters, which show unexpected (and mostly unpredictable) flaring or exploding episodes at different timescales. These transients often share the physical processes responsible for the production of the gamma-ray emission, through cosmic-ray acceleration

The magnetic field in the solar chromosphere plays a key role in the heating of the outer solar atmosphere and in the build-up and sudden release of energy in solar flares. However, uncovering the magnetic field vector in the solar chromosphere is a difficult task because the magnetic field leaves its fingerprints in the very faint polarization of the light, which is far from easy to measure and interpret. We analyse the spectropolarimetric observations obtained with the Chromospheric Layer Spectropolarimeter on board a sounding rocket. This suborbital space experiment observed the near