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    "story_id": "mp-2026-09-22-001",
    "source_story_id": "tmp-lead-gj3090b-retrograde-orbit",
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    "headline": "This Planet Orbits Against Its Star’s Spin",
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    "dek": "Six transit observations put GJ3090 b on a backward path around an M dwarf.",
    "summary": "Six transit observations put GJ3090 b on a backward path around an M dwarf.",
    "body_text": "Astronomers used six transits observed with NIRPS and HARPS to measure how the sub-Neptune GJ3090 b crosses its host star's rotating face. Their Rossiter–McLaughlin analysis yields a three-dimensional orbital obliquity of 136 degrees, with an uncertainty of minus 18 and plus 24 degrees: the planet travels retrograde relative to the star's spin. The team reports no evidence of a massive outer planet or wide stellar companion and favors an initially tilted protoplanetary disk over a later gravitational shove. This is an interpretation of a measured orientation, not a direct image of the planet's path.",
    "why_it_matters": "Six transit observations put GJ3090 b on a backward path around an M dwarf.",
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      "This is an interpretation of a measured orientation, not a direct image of the planet's path."
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    "first_published_at": "2026-09-22T09:00:00.000-04:00",
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        "text": "Six transit observations put GJ3090 b on a backward path around an M dwarf.",
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        "qualification": "This is an interpretation of a measured orientation, not a direct image of the planet's path."
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    "tags": [
      "exoplanets",
      "orbital dynamics",
      "NIRPS"
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    "image_url": "https://themachinepress.com/issues/2026-09-22/lead-gj3090b-retrograde.png",
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  "sources": [
    {
      "source_id": "source-2026-09-22-001",
      "title": "arXiv preprint 2609.24870",
      "publisher": "arXiv",
      "url": "https://arxiv.org/abs/2609.24870",
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      "published_at": "2026-09-21T12:39:06.000-04:00",
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    "title": "This Planet Orbits Against Its Star’s Spin",
    "publisher": "The Machine Press",
    "published_at": "2026-09-22T09:00:00.000-04:00",
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