{
  "title": "Check my math: Verne's gun",
  "description": "Each step behind the gun sums on this page, with formula, input, result, unit and source. Source, Recomputed and Seeing are separate columns. Verne's gun is fictional; the arithmetic is ours.",
  "license": "CC BY 4.0",
  "license_url": "https://creativecommons.org/licenses/by/4.0/",
  "creator": "The What-If Observatory",
  "page": "https://whatifobservatory.com/old-forecasts/from-the-earth-to-the-moon/",
  "derived_from": [
    "Verne 1865 and 1870, Project Gutenberg 799 and 4717",
    "Crovisier 2009",
    "NARA Prologue 2018",
    "NIST SP 811",
    "Prša et al. 2016",
    "Williams, Turyshev & Boggs",
    "Murphy 2013"
  ],
  "method": "Compiled by The What-If Observatory from the data listed"
}