[{"data":1,"prerenderedAt":421},["ShallowReactive",2],{"project-48459837":3},{"id":4,"name":5,"line":6,"line_source":7,"title":8,"url":9,"domain":10,"maker":11,"posted_at":12,"year":13,"points":14,"comments":15,"rank_in_year":16,"shown_in_year":17,"top":18,"tier":19,"category":20,"subcategory":21,"format":22,"keywords":23,"reception":28,"sentiment":29,"stance_mix":30,"scored_comments":35,"aspects":36,"strip":46,"post_text":48,"what":49,"said":97,"maker_in_thread":214,"shape":226,"grid":230,"attempts":385,"same_week":386,"maker_shows":42,"maker_hidden":413,"reader_version":414,"card":415},"48459837","Gravity","Interactive solar-system simulator, from Newton to Einstein","title","Show HN: Gravity – Interactive solar-system simulator, from Newton to Einstein","https:\u002F\u002Fqunabu.github.io\u002FGravity\u002F","qunabu.github.io","qunabu",1781005600,2026,217,56,252,4366,6,"notable","languages","educational simulator","web_app",[24,25,26,27],"solar system simulator","orbital mechanics","n-body simulation","gravity education","mixed",0.099,{"positive":31,"neutral":32,"mixed":33,"critical":34},11,10,5,8,34,{"docs":37,"idea":40,"design":43,"execution":44,"performance":45},{"positive":38,"critical":39},0,2,{"positive":41,"critical":42},4,1,{"positive":42,"critical":42},{"positive":38,"critical":41},{"positive":38,"critical":38},[47,42,38,38,47,38,42,47,47,47,47,38,38,42,33,47,38,42,47,42,33,47,33,33,42,38,38,42,47,42,38,38,47,33,33,38,33,33,33,33],3,"Just for fun and self education, I've built this over a weekend to teach myself why orbits exist, not just show planets going around. Something that was never clearly explain to me in school. \nIt opens with a guided tour that builds the idea up step by step: two bodies and the equal\u002Fopposite force, inertia (the Sun is removed and Earth just drifts straight), then \"an orbit is falling and continuously missing,\" cosmic velocities with a little rocket, Voyager 1 & 2's real gravity assists (the clock runs the actual 1977–1989 dates so the planets orbit into their grand-tour alignment and the sling",{"problem":50,"audience":56,"pricing":72,"motivation":73,"time_to_build":77,"stack":81,"openness":94,"stage":95,"team_size":96},{"value":51,"source":52,"evidence":53},"Explains why orbits exist, not just shows planets moving","maker",[54],{"id":55},"post",{"value":57,"source":58,"evidence":59},"Self-learners and students curious about orbits; kids","commenter",[60,64,68],{"id":61,"by":62,"text":63},"48460947","Brendinooo","Super fun! I might show it to my kids later today. Thanks for making it!",{"id":65,"by":66,"text":67},"48475580","mgianluc","Very nice. My kid is going to love this. Thank you!",{"id":69,"by":70,"text":71},"48481040","neurocontrarian","I like it a lot. I'll show to my daughter. Thank you!",null,{"value":74,"source":52,"evidence":75},"Self-education on why orbits exist",[76],{"id":55},{"value":78,"source":52,"evidence":79},"A weekend",[80],{"id":55},[82,86,90],{"value":83,"source":52,"evidence":84},"TypeScript",[85],{"id":55},{"value":87,"source":52,"evidence":88},"Three.js",[89],{"id":55},{"value":91,"source":52,"evidence":92},"Vite",[93],{"id":55},"open_source","launched","solo",{"praise":98,"objections":122,"requests":165,"questions":187,"alternatives":206},[99,114],{"value":100,"source":58,"evidence":101},"Fun and effective for teaching orbits and visualising 3D motion",[102,106,110],{"id":103,"by":104,"text":105},"48528477","simon145","Really cool project! I always struggled to understand the motion of the planets looking at 2D images in textbooks. So I really enjoyed the ability to click and drag to explore…",{"id":107,"by":108,"text":109},"48513937","twosky","It feels like touring space, and I like that it seems like a creative work. Regarding the part after the tour, my only regret is that I wish the camera had a bit more freedom.…",{"id":111,"by":112,"text":113},"48461595","ck2","the way the original mathematicians figured all this out absolutely melts my brain no computers, no calculators, barely working telescopes looking at the moons orbiting Jupiter…",{"value":115,"source":58,"evidence":116},"Calming music and narration",[117,121],{"id":118,"by":119,"text":120},"48522234","vj-vibing","This is so cool and the music is so calming to listen to as well. I did turn off the AI voice :)",{"id":103,"by":104,"text":105},[123,134,142,153],{"value":124,"source":58,"evidence":125},"Axial tilt animation at step 14 misrepresents precession",[126,130],{"id":127,"by":128,"text":129},"48462789","jrflo","I really liked your animations, but isn't step 14 incorrect? Earth's axis processes, but on a very long timescale. In the span of a day, the axis should be effectively…",{"id":131,"by":132,"text":133},"48461183","BigTuna","Great job! 14 is misleading though - while the context is one day, the animation depicts axial precession which takes place over ~26,000 years",{"value":135,"source":58,"evidence":136},"Focus and camera controls on planets do not work well",[137,141],{"id":138,"by":139,"text":140},"48466498","xixixao","The \"focus\" on planets doesn't work quite correctly. I love that you included true size, but it would be great if the focus worked, and one could zoom between the planets (until…",{"id":107,"by":108,"text":109},{"value":143,"source":58,"evidence":144},"Mobile layout overlaps the simulation",[145,149],{"id":146,"by":147,"text":148},"48460651","stevenalowe","Looks great but on mobile the popover covers a quarter of the screen, obscuring the sun",{"id":150,"by":151,"text":152},"48461296","iainmerrick","It works pretty well on iPhone, except the descriptive text fills most of the bottom half of the screen, overlapping the sim which is centered on the screen. If the sim were…",{"value":154,"source":58,"evidence":155},"Some physics values and rendering are inaccurate (orbital speeds, Moon tidal locking, Saturn rings)",[156,160,164],{"id":157,"by":158,"text":159},"48468854","nerdsniper","Step 5 shows the earth going as slow as 21.5 km\u002Fsec at aphelion and as fast as 39km\u002Fsec at the perihelion. I believe that should be closer to 29.3 and 30.3 km\u002Fsec, respectively.",{"id":161,"by":162,"text":163},"48472719","artemave","Very nice! Nitpick: the Moon is tidally locked, so it should always face the Earth with the same side.",{"id":138,"by":139,"text":140},[166,173,180],{"value":167,"source":58,"evidence":168},"Model satellite launches and Artemis missions",[169],{"id":170,"by":171,"text":172},"48490648","Retirology","This is fun! It would be cool to get new updates that model ongoing\u002Ffuture satellite launches or Artemis missions.",{"value":174,"source":58,"evidence":175},"Show black holes at galactic centres",[176],{"id":177,"by":178,"text":179},"48472996","Tepix","Neat. How about mentioning the massive black holes at the center of the galaxies?",{"value":181,"source":58,"evidence":182},"Show Earth forming with rotation",[183],{"id":184,"by":185,"text":186},"48474791","scamdrill","Really cool and I love educational apps like this. One suggestion is to show the rotation of the earth as the particles come together to form it rather than a static image.",[188,195,202],{"value":189,"source":58,"evidence":190},"How are relativistic effects handled in the N-body simulation",[191],{"id":192,"by":193,"text":194},"48461058","genpfault","> Einstein How are you handling relativistic effects in the N-body simulation?",{"value":196,"source":58,"evidence":197},"Performance on older devices and switch between physics modes",[198],{"id":199,"by":200,"text":201},"48524942","AmareshHebbar","I'm curious: does generating the planet textures slow down older devices, and how seamless is the switch between the two physics modes?",{"value":203,"source":58,"evidence":204},"How the narration was made",[205],{"id":103,"by":104,"text":105},[207],{"value":208,"source":58,"evidence":209},"rebound N-body simulation library",[210],{"id":211,"by":212,"text":213},"48463274","kmaitreys","For something more rigorous, I would like to take this opportunity to share rebound[1], something we use for n-body simulations in our field (planet formation). Perhaps few…",{"comments":215,"answered":41,"key":216},9,[217,220,223],{"id":218,"text":219},"48538963","I'm going to fix this soon. I've used elevenlabs for both narrator and music",{"id":221,"text":222},"48463106","Thank you all for the comments and showing the weaknesses in the model and visualisation. I'll try to understand the issues and fix them soon.",{"id":224,"text":225},"48467360","I've just published the first batch of patches and new features. I've learnt a lot during the process and from the comments which was one of the main goals, so I'm really happy…",{"commenters":227,"max_depth":33,"maker_replies":215,"first_comment_mins":228,"lifespan_hours":229},44,83,174,[231,235,237,241,243,246,250,254,256,259,262,265,269,272,276,277,279,280,281,284,285,289,290,291,294,296,299,304,306,308,312,314,317,319,321,325,327,330,333,337,339,341,344,347,349,350,352,355,357,359,362,364,369,373,377,381],[232,38,47,233,234,38],"48461809","project\u002Fmixed\u002Fdocs","rfgplk",[127,42,42,236,128,38],"project\u002Fcritical\u002Fdocs",[238,42,38,239,240,38],"48467124","commenter\u002Fneutral\u002Fnone","savoyard",[242,42,38,239,128,38],"48467179",[244,42,38,239,245,38],"48468460","SamBam",[247,39,47,248,249,38],"48463226","project\u002Fneutral\u002Fidea","nonethewiser",[251,39,38,252,253,38],"48463941","other\u002Fneutral\u002Fnone","matja",[255,39,38,239,249,38],"48465034",[257,39,42,258,245,38],"48468676","project\u002Fcritical\u002Fidea",[260,39,47,248,261,38],"48470452","DivingForGold",[263,39,38,252,264,38],"48474207","Thiez",[266,47,47,267,268,38],"48461142","project\u002Fneutral\u002Fdesign","VikingCoder",[270,47,38,239,271,38],"48462576","JKCalhoun",[273,41,47,274,275,38],"48473936","project\u002Fmixed\u002Fdesign","Syntonicles",[103,33,47,274,104,38],[218,33,38,278,11,42],"maker\u002Fneutral\u002Fnone",[221,18,38,278,11,42],[224,18,38,278,11,42],[161,282,42,283,162,38],7,"project\u002Fcritical\u002Fexecution",[211,34,38,252,212,38],[286,215,33,287,288,38],"48467040","project\u002Fpositive\u002Fidea","jumploops",[107,32,47,274,108,38],[111,31,38,252,112,38],[292,31,38,252,293,38],"48468228","TheOtherHobbes",[138,295,42,283,139,38],12,[199,297,47,298,200,38],13,"project\u002Fneutral\u002Fperformance",[300,301,47,302,303,38],"48476129",14,"project\u002Fneutral\u002Fdocs","lgcmo",[157,305,42,283,158,38],15,[184,307,33,287,185,38],16,[309,310,47,278,311,38],"48467866",17,"Invictus1001",[313,310,38,278,11,42],"48473111",[118,315,33,316,119,38],18,"project\u002Fpositive\u002Fdesign",[170,318,33,287,171,38],19,[131,320,42,236,132,38],20,[322,323,47,248,324,38],"48461346",21,"Iolaum",[326,323,38,252,112,38],"48461556",[328,323,38,252,329,38],"48470648","somat",[331,323,38,252,332,38],"48463019","em-bee",[334,335,42,283,336,38],"48462303",22,"ziofill",[177,338,47,248,178,38],23,[340,338,38,278,11,42],"48473060",[146,342,42,343,147,38],24,"project\u002Fcritical\u002Fdesign",[345,342,38,346,11,42],"48460746","maker\u002Fneutral\u002Fdesign",[348,342,38,346,11,42],"48460912",[150,342,47,274,151,38],[351,342,38,346,11,42],"48461353",[61,353,33,354,62,38],25,"project\u002Fpositive\u002Fnone",[69,356,33,354,70,38],26,[192,358,47,248,193,38],27,[360,358,38,361,11,42],"48461179","maker\u002Fneutral\u002Fidea",[65,363,33,354,66,38],28,[365,366,47,367,368,38],"48467128",29,"project\u002Fneutral\u002Fnone","ThrowawayTestr",[370,371,33,354,372,38],"48472989",30,"hi083",[374,375,33,287,376,38],"48473882",31,"roxana_haidiner",[378,379,33,354,380,38],"48500529",32,"maximedeco",[382,383,33,354,384,38],"48558967",33,"apiorno",[],[387,392,397,401,405,408],{"id":388,"name":389,"points":390,"category":391},"48445554","Performative-UI",1181,"dev_tools",{"id":393,"name":394,"points":395,"category":396},"48433756","Lathe",402,"productivity",{"id":398,"name":399,"points":400,"category":391},"48408854","Absurdly Optimized Pancakes",340,{"id":402,"name":403,"points":404,"category":391},"48447806","Gitdot",334,{"id":406,"name":407,"points":16,"category":391},"48478469","Extend UI",{"id":409,"name":410,"points":411,"category":412},"48396004","Uruky",236,"web_saas",false,"v2",{"id":416,"name":5,"line":6,"ai":413,"cat":20,"year":13,"points":14,"comments":15,"rec":28,"s":417,"top":18,"kw":418,"maker":11,"domain":10,"tier":19,"attempts":38,"strip":419,"url":9,"mix":420,"praise":100,"objection":124,"sub":21},48459837,0.1,[24,25,26,27],"3100301333300153013153551001310035505555",[31,32,33,34],1793991156360]