Clouds of gas and dust in space—like Rho Ophiuchi, shown here—mostly radiate infrared light, which human eyes can't detect. IRAS, the first infrared telescope in Earth orbit, imaged the region in 1983 ...

Embraced by ancient civilisations and modern holistic practices alike, sweating has long been a cornerstone of healing. From Mesoamerican sweat lodges to traditional Scandinavian saunas, the concept ...