"last photon orbit" meaning in English

{
  "etymology_text": "From being the closest tangential approach to a black hole, where a photon's path does not eventually fall through the event horizon.",
  "forms": [
    {
      "form": "last photon orbits",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "last photon orbit (plural last photon orbits)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Black holes",
          "orig": "en:Black holes",
          "parents": [
            "Astronomy",
            "Astrophysics",
            "Gravity",
            "Relativity",
            "Sciences",
            "Space",
            "Physics",
            "Acceleration",
            "Mechanics",
            "All topics",
            "Nature",
            "Fundamental"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Orbits",
          "orig": "en:Orbits",
          "parents": [
            "Astronautics",
            "Curves",
            "Gravity",
            "Space",
            "Applied sciences",
            "Shapes",
            "Acceleration",
            "Astrophysics",
            "Mechanics",
            "Nature",
            "Sciences",
            "Geometry",
            "Physics",
            "Astronomy",
            "All topics",
            "Mathematics",
            "Fundamental",
            "Formal sciences"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "Synonym of photon sphere"
      ],
      "id": "en-last_photon_orbit-en-noun-oR092fvg",
      "links": [
        [
          "photon sphere",
          "photon sphere#English"
        ]
      ],
      "raw_glosses": [
        "(of a black hole) Synonym of photon sphere"
      ],
      "raw_tags": [
        "of a black hole"
      ],
      "synonyms": [
        {
          "tags": [
            "synonym",
            "synonym-of"
          ],
          "word": "photon sphere"
        }
      ]
    }
  ],
  "word": "last photon orbit"
}

{
  "etymology_text": "From being the closest tangential approach to a black hole, where a photon's path does not eventually fall through the event horizon.",
  "forms": [
    {
      "form": "last photon orbits",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "last photon orbit (plural last photon orbits)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "en:Black holes",
        "en:Orbits"
      ],
      "glosses": [
        "Synonym of photon sphere"
      ],
      "links": [
        [
          "photon sphere",
          "photon sphere#English"
        ]
      ],
      "raw_glosses": [
        "(of a black hole) Synonym of photon sphere"
      ],
      "raw_tags": [
        "of a black hole"
      ],
      "synonyms": [
        {
          "tags": [
            "synonym",
            "synonym-of"
          ],
          "word": "photon sphere"
        }
      ]
    }
  ],
  "word": "last photon orbit"
}