The Largest Galaxy in the Universe, Measured at Last

Astronomy Daily · S05E157 · “The Edge of Everything” · Monday 3 August 2026

In this episode • The largest galaxy, measured at last. Ultra-deep imaging of IC 1101 in the Abell 2029 cluster has traced its outer edge for the first time: an edge radius of ~260 kpc, a diameter near 520 kpc (~1.7 million light-years), and ~3.4 trillion solar masses in stars — about 17× the width of the Milky Way. Faint outer structures aligned with cluster X-ray disturbances show it is still accreting. Source: Marrero-de la Rosa et al., “How large can galaxies be? Ultra-deep imaging of IC 1101”, accepted A&A (arXiv:2607.15340, 16 Jul 2026); phys.org, 31 Jul 2026; The Debrief, 1 Aug 2026. • Hayabusa2's record asteroid flyby. JAXA confirmed (press conference 30 Jul) that its Hayabusa2 probe passed just 400 m from the surface of near-Earth asteroid Torifune on 5 July — 744 m from centre at 18,000 km/h — the closest asteroid flyby by any mission, plus the first-ever laser ranging of an asteroid during a flyby. Torifune proved to be a contact binary. Source: JAXA press conference, 30 Jul 2026; phys.org / Japan Today (AFP), 31 Jul 2026; autoevolution, 1 Aug 2026. • UK's first orbital launch on hold. Rocket Factory Augsburg de-stacked its RFA One at SaxaVord Spaceport (Unst, Shetland) after finding a vehicle issue during hot-fire test prep (announced 28 Jul). The certified launch window opens 10 August; a successful flight would be the first orbital launch from UK soil. Source: RFA statement (X), 28 Jul 2026; Space.com, 1 Aug 2026; Shetland Times, 28 Jul 2026. • Andromeda is winding down. A new Hubble study mapping ~200 million stars across two-thirds of Andromeda's disk finds star formation has declined over ~500 million years (from ~1 to ~0.2 solar masses/year), with the steepest drop in the last 40 million years — possibly linked to an interaction with satellite galaxy M32. Source: Williams et al., The Astrophysical Journal, 27 Jul 2026; NASA/STScI release, 27 Jul 2026. Skywatch — both hemispheres • Comet 10P/Tempel 2 — perihelion 2 Aug; closest approach to Earth tonight (3 Aug). Binoculars/small scope, dark skies. Best pre-dawn from the Southern Hemisphere; ~9:30–10:30 pm local for mid-northern latitudes before moonrise. • Moon near Saturn tonight (3 Aug) — naked-eye pairing, both hemispheres, up into dawn. • Mercury at greatest western elongation (2 Aug) — low eastern horizon ~1 hr before sunrise, toward Gemini; Mars higher. Better placed for northern observers. • Diary (2 days out): Falcon 9 upper stage (2025-010D) lunar impact near Einstein Crater, 5 Aug ~06:35 UTC — ~2:35 am EDT / 11:35 pm PDT (4 Aug); North America best-timed on the dark limb. Southern Hemisphere: ~4:35 pm AEST (daylight) — await orbiter after-images. • Looking ahead: 12 Aug total solar eclipse (Greenland/Iceland/Spain) + moonless Perseid peak + six-planet dawn alignment. View partial phases only through certified ISO 12312-2 filters. Links & follow • Website, back catalogue, news feed & newsletter: astronomydaily.io • Social: @AstroDailyPod · Part of the Bitesz.com Podcast Network

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This episode includes AI-generated content.

Episode link: https://play.headliner.app/episode/34589076?utm_source=youtube