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ScienceQuiet 8d · day 13

Webb reveals 3I/ATLAS's ice is unusually dust-rich, matching Kuiper Belt bodies

New James Webb Space Telescope spectra show the interstellar comet's water ice is heavily mixed with dust, a pattern also seen in distant trans-Neptunian objects.

newest coverage 8d agosummary written 12d ago18 pieces Google NewsMastodonNewswires

What to know

  • Webb observed 3I/ATLAS three times between August 2025 and April 2026, bracketing its closest approach to the sun.
  • The comet's water-ice spectral signature is missing the faint secondary absorption features typical of solar-system comets, initially appearing anomalous.
  • Simulations show this pattern matches ice grains heavily blended with dust, a composition also seen in trans-Neptunian objects beyond Neptune.
  • The match suggests ice may form similarly in planet-forming disks around different stars, implying common raw materials for planet building across star systems.

“But when we placed it alongside distant icy worlds in our own solar system, it no longer looked out of place.”

Silvia Protopapa, Lead author, Southwest Research Institute · Mashable ↗ · Oct 26

Silvia Protopapa Lead author, Southwest Research InstituteSouthwest Research Institute team Research team conducting the Webb observations

Webb reveals 3I/ATLAS's ice is unusually dust-rich, matching Kuiper Belt bodies
Mashable

How it unfolded 1 development · click the chart to see its coverage articlesposts

Peak 5 pieces in 3h at Oct 27, 7 AM; 18 pieces over 13 days (17 articles · 1 post) Oct 26, 1 PM — 1 piece · 1 article — Google News 1Oct 26, 4 PM — 3 pieces · 3 articles — Google News 3Oct 26, 7 PM — quietOct 26, 10 PM — quietOct 27, 1 AM — quietOct 27, 4 AM — 2 pieces · 1 article · 1 post — Mastodon 1, Newswires 1Oct 27, 7 AM — 5 pieces · 5 articles — Google News 4, Newswires 1Oct 27, 10 AM — quietOct 27, 1 PM — quietOct 27, 4 PM — quietOct 27, 7 PM — quietOct 27, 10 PM — quietOct 28, 1 AM — quietOct 28, 4 AM — quietOct 28, 7 AM — quietOct 28, 10 AM — quietOct 28, 1 PM — quietOct 28, 4 PM — quietOct 28, 7 PM — quietOct 28, 10 PM — quietOct 29, 1 AM — 2 pieces · 2 articles — Google News 2Oct 29, 4 AM — quietOct 29, 7 AM — quietOct 29, 10 AM — quietOct 29, 1 PM — quietOct 29, 4 PM — quietOct 29, 7 PM — quietOct 29, 10 PM — quietOct 30, 1 AM — quietOct 30, 4 AM — quietOct 30, 7 AM — quietOct 30, 10 AM — quietOct 30, 1 PM — quietOct 30, 4 PM — quietOct 30, 7 PM — quietOct 30, 10 PM — quietOct 31, 1 AM — quietOct 31, 4 AM — quietOct 31, 7 AM — 3 pieces · 3 articles — Google News 3Oct 31, 10 AM — quietOct 31, 1 PM — quietOct 31, 4 PM — quietOct 31, 7 PM — quietOct 31, 10 PM — quietNov 1, 1 AM — quietNov 1, 3 AM — quietNov 1, 6 AM — quietNov 1, 9 AM — 2 pieces · 2 articles — Google News 2Nov 1, 12 PM — quietNov 1, 3 PM — quietNov 1, 6 PM — quietNov 1, 9 PM — quietNov 2, 12 AM — quietNov 2, 3 AM — quietNov 2, 6 AM — quietNov 2, 9 AM — quietNov 2, 12 PM — quietNov 2, 3 PM — quietNov 2, 6 PM — quietNov 2, 9 PM — quietNov 3, 12 AM — quietNov 3, 3 AM — quietNov 3, 6 AM — quietNov 3, 9 AM — quietNov 3, 12 PM — quietNov 3, 3 PM — quietNov 3, 6 PM — quietNov 3, 9 PM — quietNov 4, 12 AM — quietNov 4, 3 AM — quietNov 4, 6 AM — quietNov 4, 9 AM — quietNov 4, 12 PM — quietNov 4, 3 PM — quietNov 4, 6 PM — quietNov 4, 9 PM — quietNov 5, 12 AM — quietNov 5, 3 AM — quietNov 5, 6 AM — quietNov 5, 9 AM — quietNov 5, 12 PM — quietNov 5, 3 PM — quietNov 5, 6 PM — quietNov 5, 9 PM — quietNov 6, 12 AM — quietNov 6, 3 AM — quietNov 6, 6 AM — quietNov 6, 9 AM — quietNov 6, 12 PM — quietNov 6, 3 PM — quietNov 6, 6 PM — quietNov 6, 9 PM — quietYesterday, 12 AM — quietYesterday, 3 AM — quietYesterday, 6 AM — quietYesterday, 9 AM — quietYesterday, 12 PM — quietYesterday, 3 PM — quietYesterday, 6 PM — quietYesterday, 9 PM — quietToday, 12 AM — quietToday, 3 AM — quietToday, 6 AM — quietToday, 9 AM — quiet 1
Oct 27Oct 28Oct 29Oct 30Oct 31Nov 1Nov 2Nov 3Nov 4Nov 5Nov 6now · 11:25 AM ET
  1. 1

    Findings published in The Astrophysical Journal Letters and widely covered

    The Southwest Research Institute team's paper, led by Silvia Protopapa, was published in The Astrophysical Journal Letters and reported by outlets including Sci.News and Mashable.

    “At first glance, 3I/ATLAS looks different from the icy comets we know…”
    — Silvia Protopapa, Lead author, Southwest Research Institute · source
  2. background

    Researchers match 3I/ATLAS's ice pattern to trans-Neptunian objects — Comparing the comet's data to existing Webb observations of trans-Neptunian objects, the team found several icy worlds beyond Neptune share the same dust-rich ice signature, including carbon dioxide ice and carbon-rich compounds.

  3. background

    Simulations link missing ice features to heavy dust mixing — Computer simulations showed that dust-blended ice grains scatter light in a way that suppresses the fainter absorption marks, explaining the comet's unusual spectral fingerprint without requiring an exotic ice composition.

  4. background

    Study finds 3I/ATLAS's ice signature lacks expected faint absorption marks — Analysis of the Webb spectra showed that while most comets display one strong and two faint water-ice absorption features, 3I/ATLAS's two faint marks barely registered or were absent altogether.

  5. background

    Webb completes third observation as comet recedes from sun — The team's three Webb observations spanned before and after 3I/ATLAS's perihelion, with the final look in April 2026 showing a second population of ice-rich grains as the comet moved away from the sun.

  6. background

    Webb makes first observation of interstellar comet 3I/ATLAS — A Southwest Research Institute-led team began pointing the James Webb Space Telescope at 3I/ATLAS, the third known interstellar object, ahead of its closest pass by the sun.

Also covered reported alongside — the timeline has no entry for these yet

  1. 5 outlets The interstellar comet just brought us closer to our galactic neighbours – 3I/ATLAS chemistry revealed something very special about our Solar System

    first by BBC Sky at Night Magazine, 12d ago · also The Economic Times, The Daily Galaxy, inkl, Around Prague

    6 more headlines
  2. 3 outlets Webb Finds Dust-Rich Water Ice in Interstellar Comet 3I/ATLAS

    first by Sci.News, 12d ago · also Mashable, NewsBytes

    2 more headlines
  3. 2 outlets Interstellar comet 3I/ATLAS contains planet-building materials from worlds beyond Neptune

    first by The Brighter Side of News, 12d ago · also Discover Magazine

    2 more headlines
  4. 2 outlets Webb spotted a subtle difference in the interstellar comet's ice

    first by Mashable SEA, 12d ago · also Mashable

    1 more headline