S05E158 — “The Crater Makers” · Tuesday 4 August 2026. Four stories on cosmic impacts — and a new map of the X-ray sky — plus a both-hemispheres skywatch. ① A dead Falcon 9 is about to crater the Moon ● A spent SpaceX Falcon 9 upper stage (catalogued 2025-010D) is predicted to strike the Moon near Einstein Crater on 5 Aug 2026 at ~06:35 UTC — the second documented uncontrolled rocket impact on the Moon. ● The stage launched Firefly’s Blue Ghost and ispace’s Resilience landers in Jan 2025, then was stranded in a chaotic Earth orbit for ~18 months. Impact speed ~2.4 km/s (~5,400 mph); expected crater ~17–27 m across. ● Prediction by Bill Gray (Project Pluto). NASA’s LRO can image the site before and after; a ~two-dozen-author campaign is coordinating observers to chase the ejecta plume. ● Governance angle: no international framework governs cislunar debris — a growing hazard as lunar traffic increases (callback to E154’s distant-retrograde-orbit debris study). Sources: Space.com / Forbes / Reuters (Cris Tolomia) — impact preview, 31 Jul–3 Aug 2026 · Project Pluto (Bill Gray) — 2025-010D impact page · ZME Science — impact timing, 3 Aug 2026 ② Neptune’s inner moons: shrapnel of a shattered world ● JWST NIRSpec spectroscopy of Neptune’s inner moons Larissa, Galatea and Proteus (Caltech; lead author Ryleigh Davis, Mike Brown’s group) detected magnesium-rich phyllosilicates — clay minerals that require liquid water and had never been seen beyond Jupiter. ● The clays imply the material came from much larger, water-bearing worlds — evidence that Neptune’s original regular moon system was destroyed when Triton (a captured Kuiper Belt object) arrived. ● Proteus, the largest of the three, lacks the clays — possibly re-heated and reprocessed after re-forming, hiding its history. Sources: Davis et al., Science Advances, 29 July 2026 · Caltech / phys.org press coverage, 29 Jul–3 Aug 2026 · Space.com (Charles Q. Choi), 3 Aug 2026 ③ “Charbroiled within hours”: impact dust and the dinosaurs ● New modelling (Brandon Johnson et al., Purdue) argues ultrafine impact dust from Chicxulub acted as an insulating blanket, raising surface heating ~3.5× above the spherule-only estimate — enough to ignite global wildfires and kill exposed animals within hours. ● The same dust then blocked sunlight for years — so the model adds a ferocious opening act to the established “impact winter,” rather than replacing it. Sheltering underground or underwater aided survival. ● Caveat: the strongest physical wildfire evidence is so far confined to North America (per UCL’s Alfio Chiarenza, not involved in the study); a truly global fire record remains unconfirmed. Sources: Johnson, Johnson, Wakita & Robertson, JGR: Biogeosciences, 2026 · Popular Science / Space.com / ZME Science, 28 Jul–2 Aug 2026 ④ eROSITA DR2 — the X-ray sky doubles ● The eROSITA telescope (SRG mission) released its second data set (DR2) on 31 July 2026: ~1.9 million pointlike and ~64,000 extended X-ray sources from the first three all-sky scans — nearly doubling the previously released eROSITA catalogue. ● For scale: ROSAT catalogued ~130,000 sources in the 1990s and was the benchmark for 30 years. Lead author: Miriam Ramos-Ceja (MPE). ● DR2 delivers the first direct census of cataclysmic-variable binaries sufficient to explain the decades-old Galactic Ridge X-ray Emission. It coincides with SDSS DR20 (Black Hole Mapper), enabling 3D mapping of active black holes. Sources: Ramos-Ceja et al. (eROSITA-DE), arXiv:2607.27772; DR2 release · Max Planck Society press release, 29 July 2026 · phys.org, 31 Jul 2026 Skywatch — both hemispheres ● Falcon 9 impact (5 Aug, ~06:35 UTC): not naked-eye; ejecta plume a long shot for advanced amateurs in the Americas near the western limb (~2:35 a.m. EDT)....
