00:47 The mystery of the missing dark matterDark matter makes up most of the matter in the Universe, and is thought to be needed for galaxies to form. But four years ago, astronomers made a perplexing, and controversial discovery: two galaxies seemingly devoid of dark matter. This week the team suggests that a cosmic collision may explain how these, and a string of other dark-matter-free galaxies, could have formed. Research article: van Dokkum et al. News and Views: Giant collision created galaxies devoid of dark matter 08:39 Research HighlightsHow fossil fuel burning has caused levels of helium to rise, and a high-efficiency, hybrid solar-energy system. Research Highlight: Helium levels in the atmosphere are ballooning Research Highlight: Flower power: ‘Sunflower’ system churns out useful energy 10:49 Researchers experiences of the war in UkraineWe hear the stories of scientists whose lives have been affected by Russia’s invasion of Ukraine, including researchers who have become refugees, soldiers and activists in the face of a horrifying conflict. Nature Feature: How three Ukrainian scientists are surviving Russia’s brutal war 20:46 Imaging the black hole at the centre of the Milky WayLast week, a team of researchers released an image of Sagittarius A*, the supermassive blackhole at the centre of our galaxy. We hear how they took the image and what it is revealing about these enormous objects. Nature News: Black hole at the centre of our Galaxy imaged for the first time Subscribe to Nature Briefing, an unmissable daily round-up of science news, opinion and analysis free in your inbox every weekday. See acast.com/privacy for privacy and opt-out information.