[{"data":1,"prerenderedAt":827},["ShallowReactive",2],{"layer:phases-of-the-moon:extend":3},{"layer":4,"contentHash":802,"dependencyHashes":803,"approval":820,"releaseId":826},{"schemaVersion":5,"conceptId":6,"locale":7,"depth":8,"revision":5,"title":9,"subtitle":10,"summary":11,"objectives":12,"estimatedMinutes":18,"plate":19,"blocks":40,"sourceIds":797,"reviewStatus":798,"authoring":799},1,"phases-of-the-moon","en","extend","To the wobble, the far side and the far future","Libration, Chandrayaan-3 and the south pole, deep time, other calendars, puzzles and open questions","Push past the settled parts of the topic: measure libration for yourself, trace the far side from Luna 3 to Chandrayaan-3, work out why total eclipses have an expiry date, compare world calendars, and take on puzzles and open questions nobody has fully answered.",[13,14,15,16,17],"Explain libration and why it raises the visible fraction of the Moon to about 59% without ever showing more than half at once.","Trace the history of far-side and south-pole exploration from Luna 3 to Chandrayaan-3, and explain why the south pole specifically was chosen.","Estimate, from the recession rate and the Moon's and Sun's angular sizes, roughly how long total solar eclipses have left to occur.","Compare how the Hindu, Islamic, Hebrew and Gregorian calendars each handle the mismatch between lunar months and the solar year.","Attempt harder calculation puzzles and engage with open questions that current research has not fully settled.",45,{"title":20,"rows":21},"Lesson plate",[22,25,28,31,34,37],{"label":23,"value":24},"Depth","Extend",{"label":26,"value":27},"Reading time","about 45 minutes",{"label":29,"value":30},"Prior knowledge","Deepen: tidal locking, recession, the two tilts",{"label":32,"value":33},"Chapters","9",{"label":35,"value":36},"Projects","Libration photo comparison (weeks to months)",{"label":38,"value":39},"Labs","Mission-firsts match-up",[41,45,51,76,82,85,110,123,128,131,146,151,154,178,183,187,211,216,219,244,255,260,266,270,275,278,295,300,318,360,365,368,372,383,388,416,421,426,431,434,458,472,477,481,486,489,497,501,526,534,547,551,556,559,610,615,619,652,656,661,664,766,781],{"id":42,"type":43,"markdown":44},"intro-extend","prose","You now know more about the Moon's phases than most adults ever learn: the geometry, the names, the maths behind the calendar, and the physics that locks its rotation. This layer takes you to the edges of that knowledge — a wobble too small to see without care, a hemisphere nobody saw for all of human history until 1959, a robotic mission that put India on a patch of ground nobody had ever safely reached, and a question about the very distant future that nobody alive today will see answered.\n\nThere are puzzles here that will take real effort, and open questions that nobody, anywhere, has fully solved.",{"id":46,"type":47,"variant":48,"title":49,"markdown":50},"intro-how-to-read","callout","try_it","How to use this lesson","This is not a lesson to finish in one sitting. Read a chapter, try its problem, and come back another day for the next. The libration project and the moon-diary comparison both need weeks or months, not minutes.",{"id":52,"type":53,"tone":54,"items":55},"intro-key-numbers","spec","neutral",[56,60,64,68,72],{"label":57,"big":58,"value":59},"Visible over time","59%","Of the Moon's surface, thanks to libration — never all at once.",{"label":61,"big":62,"value":63},"First far-side photo","1959","Luna 3, ending millennia of pure speculation.",{"label":65,"big":66,"value":67},"Chandrayaan-3 landing","23 August 2023","Near 69.373° S, at Statio Shiv Shakti.",{"label":69,"big":70,"value":71},"Moon's axial tilt","1.5424°","Small enough to leave some polar crater floors in permanent shadow.",{"label":73,"big":74,"value":75},"Total eclipses have left","~267 million yr","A rough, order-of-magnitude estimate computed in this layer.",{"id":77,"type":78,"title":79,"eyebrow":80,"navLabel":81},"ch1","chapter","Libration: seeing round the edge","Chapter 01","1 Libration",{"id":83,"type":43,"markdown":84},"ch1-libration","Deepen mentioned, in passing, that the Moon rocks slightly as it orbits. This wobble is called **libration**, and it is the reason the oft-quoted \"50% of the Moon is visible from Earth\" is actually wrong. The true figure, averaged over years of watching, is **59%**.",{"id":86,"type":87,"caption":88,"columns":89,"rows":94},"ch1-libration-table","table","The two kinds of libration and what they let us see",[90,91,92,93],"Kind","Size","Cause","Effect",[95,100,105],[96,97,98,99],"Libration in longitude","±7.9°","The Moon's orbital speed varies (ellipse) but its spin rate is constant, so the two drift in and out of step through the month","Lets us peek a little around the east and west edges in turn",[101,102,103,104],"Libration in latitude","±6.7°","The Moon's spin axis is tilted a small amount relative to its orbital plane","Lets us peek a little over the north and south poles in turn",[106,107,108,109],"Diurnal libration","±1°","An observer on Earth's surface is not exactly at Earth's centre, and Earth rotates under them in the course of one night","A small additional daily wobble, smallest of the three",{"id":111,"type":112,"title":113,"problem":114,"steps":115,"help":121},"we-libration-fractions","worked_example","Working out the 59% figure from the two main librations","Longitude libration reaches about 7.9° each way and latitude libration about 6.7° each way. Explain, in outline, how these combine to raise the visible fraction from 50% to about 59%.",[116,117,118,119,120],"With **no** libration at all, an observer on Earth would see exactly one hemisphere: **50%** of the surface, forever, unchanging.","Libration in longitude lets you see slightly past the eastern limb at one point in the month and slightly past the western limb two weeks later — different strips of terrain at different times, not simultaneously.","Libration in latitude does the same for the northern and southern polar regions.","Added together over a full cycle (longitude, latitude, and the smaller diurnal wobble combining in different directions at different times), the *total* strip of surface that becomes visible at some point or other reaches about **59%**.","That leaves 41% permanently facing us with no wobble needed, 18% visible only some of the time from the wobbling edge zones, and 41% that never becomes visible from Earth under any circumstances, however long you wait.",{"simplerExplanation":122},"Without any wobble you would only ever see 41%... actually the plain half. The wobble lets you peek a bit further round each edge at different times, so different 18%-wide strips become visible on different days, adding up to 59% overall, never all at once.",{"id":124,"type":47,"variant":125,"title":126,"markdown":127},"ch1-never-simultaneous","nuance","You can never see 59% at once","This is the detail that trips people up. The 59% is a *total*, collected across weeks and months of careful watching, never a single view. At any one instant, you are still only seeing very close to one true half of the Moon — the wobble just means *which* half shifts slightly, day by day.",{"id":129,"type":43,"markdown":130},"ch1-project","**Project: catch libration on camera.** This is a genuine amateur-astronomy project used by real observers.\n\n1. Choose a distinctive feature very close to the Moon's edge — the crater Mare Crisium, near the eastern limb, is a good, easy-to-recognise target.\n2. On several full-moon nights, spread across two or three months, photograph the Moon (a phone held steady against a pair of binoculars, or a basic camera, works) and note the exact date.\n3. Compare the photos side by side. On some nights the feature will sit closer to the edge; on others it will have rotated visibly further round, or further from the edge, than on other nights.\n4. If you can, note the date each time and try to match your \"further round\" nights against the numbers in the table above — the longitude wobble has roughly its own monthly rhythm.\n\nNobody expects a perfect result from a phone camera. Even a rough side-by-side comparison, done honestly, is a real measurement of a wobble that would be genuinely difficult to explain to someone who has only ever read about it.",{"id":132,"type":133,"component":134,"componentVersion":5,"config":135,"objective":140,"textAlternative":141,"help":142},"lab-moon-libration","interactive","moon-phase",{"startDay":136,"views":137,"showNames":139,"showTithi":139,"quizRounds":136},0,[138],"from-space",false,"Step slowly through a full month from the space view and imagine a fixed marker on the Moon's eastern edge; picture how far round it that marker's shadow-line reveals as the month goes by.","This lab is used here in an unusual way: not for the phase shape itself, but as a stand-in for imagining libration. Set to the space view, it shows the Moon's orbit and the Sun's light sweeping across it as the day-of-month slider moves.\n\nThe lab itself does not animate the small orbital-speed wobble that causes real libration (that effect is only a few degrees, far too subtle for this simplified model). Use it instead as a prop: as you move the slider through the month, picture a small flag stuck right at the edge of the visible disc. In reality, that flag would drift a few degrees into view and back out again over the month, in the rhythm described in the table above, even though the basic day\u002Fnight boundary shown by the lab stays fixed in shape. The textbook animation for real libration is worth searching for online (NASA's Scientific Visualisation Studio publishes one); this lab is a scaffold for understanding it, not a substitute.",{"hints":143},[144,145],"Focus on the very edge of the lit disc, not the middle, since that is where libration's effect would show up.","Compare this simplified model with the project above: a real photograph captures the wobble this lab cannot show.",{"id":147,"type":78,"title":148,"eyebrow":149,"navLabel":150},"ch2","The far side is not the dark side","Chapter 02","2 The far side",{"id":152,"type":43,"markdown":153},"ch2-farside-history","Every part of the Moon gets roughly two weeks of sunlight and two weeks of darkness in every synodic month, including the far side. It is no darker, on average, than the side we see. It earned the nickname \"dark side\" only because it was **unknown**, not because it was unlit — and Pink Floyd's famous album title has done more than any textbook to keep that confusion alive.",{"id":155,"type":156,"title":157,"items":158},"ch2-farside-timeline","timeline","Sixty years of far-side firsts",[159,162,166,170,174],{"time":62,"title":160,"text":161},"Luna 3","The Soviet Luna 3 probe swings around the Moon and radios back the first, grainy photographs of the far side, ending millennia in which nobody knew what it looked like.",{"time":163,"title":164,"text":165},"1968","Apollo 8","The three-man crew becomes the first humans to see the far side with their own eyes, orbiting the Moon on a Christmas Eve mission that never landed.",{"time":167,"title":168,"text":169},"2009","Chandrayaan-1","India's first lunar mission detects water molecules and hydroxyl across the lunar surface, a discovery that helped redirect global interest towards the poles.",{"time":171,"title":172,"text":173},"2019","Chang'e-4","China's Chang'e-4 becomes the first mission ever to land, rather than merely photograph or orbit, the far side, touching down in the South Pole-Aitken basin and requiring a relay satellite just to keep in contact with Earth, since the far side never faces home.",{"time":175,"title":176,"text":177},"2023","Chandrayaan-3","India's Vikram lander touches down near the lunar south pole (on the near side, but in the same generally difficult polar terrain), at a site later named Statio Shiv Shakti.",{"id":179,"type":47,"variant":180,"title":181,"markdown":182},"ch2-farside-terrain","observation","The far side looks strikingly different","Photographs reveal a genuine surprise: the far side is covered in **craters** but has very few of the smooth, dark **maria** (\"seas\") that dominate the near side's familiar face. The leading explanation is that the near side's crust is thinner, partly because of the heat retained from the giant impact that may have formed the Moon and from Earth's own gravitational effects during the Moon's early, molten history, letting ancient lava reach the surface more easily there than on the thicker-crusted far side. This remains an active area of research: the exact cause of the crustal difference is not yet fully settled.",{"id":184,"type":47,"variant":125,"title":185,"markdown":186},"ch2-why-relay-needed","Why Chang'e-4 needed a relay satellite just to phone home","Because the Moon is tidally locked, the far side never faces Earth at any point in its orbit, which means no direct radio link is ever possible between a far-side lander and Earth — the bulk of the Moon itself always blocks the signal. China solved this by first launching a small relay satellite, Queqiao, into a special orbit beyond the Moon from which it could see both Chang'e-4 and Earth at once, bouncing commands and data between them. No earlier mission had ever needed to solve this particular problem, precisely because no earlier mission had landed anywhere the direct view of Earth was permanently blocked.",{"id":188,"type":133,"component":189,"componentVersion":5,"config":190,"objective":209,"textAlternative":210},"lab-match-firsts","match-pairs",{"prompt":191,"mode":192,"pairs":193},"Match each mission to the far-side or south-pole milestone it achieved.","connect",[194,197,200,203,206],{"a":195,"b":196},"Luna 3 (1959)","First photographs of the far side",{"a":198,"b":199},"Apollo 8 (1968)","First humans to see the far side directly",{"a":201,"b":202},"Chandrayaan-1 (2008-09)","First Indian mission; detected water molecules on the Moon",{"a":204,"b":205},"Chang'e-4 (2019)","First landing on the far side",{"a":207,"b":208},"Chandrayaan-3 (2023)","First landing so close to the lunar south pole","Connect each historic lunar mission to the specific first it achieved.","Five missions are matched to five firsts: Luna 3 to the first far-side photographs; Apollo 8 to the first humans to see the far side directly; Chandrayaan-1 to India's first lunar mission and its detection of water; Chang'e-4 to the first landing on the far side; and Chandrayaan-3 to the first landing so far south on the Moon. Together they trace sixty-plus years of a hidden hemisphere slowly becoming a mapped, and finally a visited, one.",{"id":212,"type":78,"title":213,"eyebrow":214,"navLabel":215},"ch3","Chandrayaan-3 and the lunar south pole","Chapter 03","3 Chandrayaan-3",{"id":217,"type":43,"markdown":218},"ch3-ch3-mission","On **23 August 2023**, the Vikram lander of India's **Chandrayaan-3** mission touched down at about 69.373° south, 32.319° east — further south than any earlier successful soft landing, near enough to the pole to be classed as **polar terrain**. India marks the anniversary of the landing as **National Space Day**. The landing site was later named **Statio Shiv Shakti**.",{"id":220,"type":87,"caption":221,"columns":222,"rows":225},"ch3-mission-spec","Chandrayaan-3 at a glance",[223,224],"Item","Detail",[226,229,232,235,238,241],[227,228],"Launch","14 July 2023, from Satish Dhawan Space Centre",[230,231],"Landing","23 August 2023, near 69.373° S, 32.319° E",[233,234],"Lander","Vikram, named for Vikram Sarabhai, the founder of India's space programme",[236,237],"Rover","Pragyan, which travelled short distances across the surface analysing soil composition",[239,240],"Power source","Solar panels, requiring sunlight, hence the mission's lifetime tied to the lunar day",[242,243],"Mission life","Designed for one lunar day (about 14.8 Earth days of continuous sunlight)",{"id":245,"type":112,"title":246,"problem":247,"steps":248,"help":253},"we-lunar-day","Why a lunar mission's working life is measured in Earth-days, not months","Chandrayaan-3's lander and rover ran on solar power and were designed to operate for one lunar day. Given that a full lunar day-night cycle equals one synodic month, work out roughly how many Earth-days of continuous sunlight that means, and how many days of darkness and cold followed.",[249,250,251,252],"One full lunar day-night cycle equals one synodic month: 29.53 Earth-days.","Daylight is (very roughly) half of that: 29.53 ÷ 2 = **14.77 Earth-days**, close to a fortnight.","Night is the other half, also about 14.77 Earth-days, during which temperatures near the equator can fall below −150 °C.","Solar-powered hardware not designed to survive that cold and dark typically cannot be woken again once night falls, which is why Vikram and Pragyan's primary mission was measured in one lunar day, not weeks or months by an Earth calendar.",{"simplerExplanation":254},"Half a lunar month is sunlight, half is freezing darkness. A solar-powered lander built for 'one lunar day' is really built to survive about two Earth weeks.",{"id":256,"type":47,"variant":257,"title":258,"markdown":259},"ch3-why-south-pole","definition","Why the south pole, specifically?","The Moon's axial tilt is only about **1.5424°** (Deepen, Chapter 6) — remarkably close to upright compared with Earth's 23.4°. Near the poles, that means sunlight arrives almost horizontally, all year, with almost no seasonal change. Inside deep polar craters whose rims block that low sunlight completely, the floor can sit in **permanent shadow**, some of it for billions of years, cold enough to trap water ice that would evaporate anywhere sunlit. That ice is the prize: a source of drinking water, breathable oxygen (by splitting the water) and even rocket fuel (hydrogen and oxygen) for future missions, without hauling everything from Earth.",{"id":261,"type":262,"conceptId":263,"relation":264,"explanation":265},"ch3-connect-exploration","connection","exploration","related_to","Space missions are a modern chapter in the much older story of exploration: new frontiers, new resources, new risks, and new questions about who benefits and who decides where to go next.",{"id":267,"type":47,"variant":180,"title":268,"markdown":269},"ch3-not-alone","India is not racing alone","Chandrayaan-3 landed a few weeks before Russia's Luna-25 mission, aimed at a similar polar region, crashed during its own landing attempt — a reminder of just how difficult a soft polar landing is, even for a country with a long history of lunar missions. The United States' Artemis programme has also named the lunar south pole as its own target for future crewed landings, and China has announced its own crewed lunar ambitions for later this decade. The south pole has gone, within about fifteen years, from an obscure, ignored region to the most contested piece of real estate beyond Earth.",{"id":271,"type":78,"title":272,"eyebrow":273,"navLabel":274},"ch4","Water ice and the next fifty years","Chapter 04","4 Water ice",{"id":276,"type":43,"markdown":277},"ch4-water-history","The south pole was not always the destination of choice. Early Moon missions, including all six crewed Apollo landings, aimed at the near-equatorial regions, where sunlight, warmth and flat ground made landing and working far easier. The shift towards the poles is recent, and it is a direct result of evidence, gathered piece by piece, that there might be something worth digging for.\n\nThat history is worth tracing mission by mission, because it shows science working the way it usually does in practice: not one dramatic discovery, but a slow accumulation of clues, each one making the next mission's target a little more precise.",{"id":279,"type":280,"title":281,"items":282},"ch4-evidence-steps","steps","How the case for polar water ice was built, mission by mission",[283,287,290,293],{"title":284,"tag":285,"text":286},"Clementine (1994)","NASA","Radar data hinted at ice deposits in permanently shadowed polar craters, the first serious modern evidence.",{"title":201,"tag":288,"text":289},"ISRO","India's Moon Impact Probe and NASA's M3 instrument aboard the same spacecraft detect water molecules and hydroxyl spread across the lunar surface, not just at the poles.",{"title":291,"tag":285,"text":292},"LCROSS (2009)","A spent rocket stage is deliberately crashed into the shadowed crater Cabeus; the resulting plume of debris, analysed by a trailing spacecraft, confirms water ice mixed into the soil.",{"title":207,"tag":288,"text":294},"Pragyan's instruments analyse soil composition in situ near the south pole, adding ground-truth data from the exact kind of terrain the earlier orbital hints pointed to.",{"id":296,"type":47,"variant":297,"title":298,"markdown":299},"ch4-why-it-matters","example","Why ice on the Moon changes the maths of exploration","Lifting one litre of water from Earth's surface into lunar orbit costs a rocket enormous amounts of fuel — historically, tens of thousands of dollars per kilogram, even after recent reductions. If usable water ice sits waiting on the Moon itself, future crews could draw drinking water, oxygen and even rocket propellant locally, instead of carrying every drop from home. That single idea, more than any other, is why the \"empty, dead\" south pole is now one of the most closely studied places in the Solar System, targeted by India, the USA (through the Artemis programme), China and others.",{"id":301,"type":302,"prompt":303,"options":304,"explanation":317},"predict-ice-challenge","prediction","What is the single biggest engineering challenge in actually using lunar polar water ice, beyond simply finding it?",[305,308,311,314],{"id":306,"label":307},"a","The ice might be radioactive",{"id":309,"label":310},"b","It sits in permanently shadowed craters that are extremely cold and receive no direct sunlight for power or warmth",{"id":312,"label":313},"c","There is no gravity to hold equipment in place",{"id":315,"label":316},"d","The Moon has no north or south, so instruments cannot navigate","**b.** The very darkness that preserves the ice also defeats solar power, the main energy source every lunar mission so far has relied on, and the extreme cold (down to around −230 °C in the coldest permanently shadowed craters, among the coldest measured temperatures anywhere in the Solar System) is punishing for equipment. Extracting the ice means operating machinery in permanent darkness and extreme cold, or working at a nearby sunlit crater rim and reaching into the shadow — a genuinely hard engineering problem that mission planners are still actively solving.",{"id":319,"type":133,"component":320,"componentVersion":5,"config":321,"objective":358,"textAlternative":359},"lab-sort-evidence-strength","sort-game",{"prompt":322,"bins":323,"seconds":136,"items":333},"Sort each piece of evidence for lunar water ice by how strong it is on its own.",[324,327,330],{"id":325,"label":326},"strong","Strong, direct evidence",{"id":328,"label":329},"suggestive","Suggestive, indirect evidence",{"id":331,"label":332},"not-evidence","Not evidence either way",[334,338,342,346,350,354],{"id":335,"label":336,"bin":325,"why":337},"i1","LCROSS crashed into a shadowed crater and detected water in the debris plume","A direct physical\u002Fspectral detection of water in material excavated from the exact target location — about as direct as evidence gets without physically drilling and returning a sample.",{"id":339,"label":340,"bin":328,"why":341},"i2","Radar signatures in some polar craters that Clementine data suggested might indicate ice","Radar signatures consistent with ice are not proof of ice; other materials can produce similar signals, which is exactly why later, more direct missions were needed.",{"id":343,"label":344,"bin":325,"why":345},"i3","Chandrayaan-1 detected water\u002Fhydroxyl signatures spread across the lunar surface, not just the poles","A direct spectral detection, though it showed widespread thin water\u002Fhydroxyl rather than the thick polar ice deposits hoped for — still a genuine, direct measurement.",{"id":347,"label":348,"bin":331,"why":349},"i4","The Moon looks grey and lifeless in photographs","Visual appearance says nothing about subsurface or shadowed-crater ice, which would not be visible in an ordinary photograph either way.",{"id":351,"label":352,"bin":328,"why":353},"i5","Comets and asteroids have delivered water-ice to airless bodies elsewhere in the Solar System","A plausible delivery mechanism supports the idea that ice could be there, but does not by itself prove it is on the Moon specifically.",{"id":355,"label":356,"bin":328,"why":357},"i6","Permanently shadowed craters near the poles are cold enough that ice would not evaporate away","This explains why ice *could* survive there if delivered, but a cold trap being available is not the same as evidence that it was actually filled.","Sort six claims about lunar water ice by whether they are strong direct evidence, merely suggestive, or not evidence at all.","Six claims are sorted into three bins. **Strong, direct evidence:** the LCROSS impact plume detection, and Chandrayaan-1's spectral detection of water\u002Fhydroxyl. **Suggestive, indirect evidence:** early radar signatures, the fact that comets deliver ice elsewhere in the Solar System, and the existence of cold traps that could preserve ice if it arrived. **Not evidence either way:** the Moon's grey, lifeless appearance in ordinary photographs, which says nothing about what is hidden in permanent shadow. The pattern: a plausible mechanism or a suitable environment is not the same as a direct detection, and separating the two is exactly the skill Investigate's evidence-sorting lab (in a different topic) also builds.",{"id":361,"type":78,"title":362,"eyebrow":363,"navLabel":364},"ch5","Deep time: a closer Moon, a shorter day","Chapter 05","5 Deep time",{"id":366,"type":43,"markdown":367},"ch5-deeptime","Deepen showed the Moon receding at 3.8 cm a year, confirmed by both laser ranging and fossil coral growth rings. Run that story backwards, over not decades but **billions of years**, and the picture becomes dramatic.",{"id":369,"type":47,"variant":297,"title":370,"markdown":371},"ch5-early-moon","A very different Earth-Moon system, billions of years ago","Most current models place the Moon's formation about 4.5 billion years ago, from debris thrown up by a giant impact between the young Earth and a Mars-sized body. In that early era, the Moon orbited far closer than today, Earth's own rotation was considerably faster (widely cited estimates put the very earliest day at only a handful of hours), and the ocean tides raised by such a close, fast-orbiting Moon would have been dramatically higher than any tide known today. Every one of these effects has been slowly relaxing ever since, at a rate that itself has changed over geological time as continents drifted into different tide-friendly and tide-resistant configurations.",{"id":373,"type":112,"title":374,"problem":375,"steps":376,"help":381},"we-eclipse-cessation","Estimating when total solar eclipses will end","A total solar eclipse needs the Moon's angular size, even at its closest approach (perigee, 363,300 km), to be at least as large as the Sun's average angular size (0.5331°). If the Moon's perigee distance grows at today's recession rate, roughly how many years from now would perigee alone become too far for totality?",[377,378,379,380],"Find the perigee distance at which the Moon's angular size would exactly equal the Sun's: solving 2×arctan((moon radius)÷distance) = 0.5331° gives distance ≈ **373,463 km**.","Today's perigee is about 363,300 km, so perigee would need to grow by 10,163 km.","At 3.8 cm\u002Fyear, that growth takes (10,163 km × 100,000 cm\u002Fkm) ÷ 3.8 cm\u002Fyear ≈ **267 million years**.","This is a rough, order-of-magnitude estimate, not a prediction anyone should take as precise — see the careful note below — but it correctly captures the key idea: because the Moon is receding and the Sun is not, the coincidence that currently makes total solar eclipses possible at all is temporary on a cosmic, not a human, timescale.",{"simplerExplanation":382},"The Moon just barely looks big enough to cover the Sun today. As it drifts further away it will look smaller and smaller, and eventually — a very, very long time from now — even its closest approach won't be big enough to cover the Sun completely.",{"id":384,"type":47,"variant":385,"title":386,"markdown":387},"ch5-model-limit","model_limit","Why this number should not be quoted as a fact","This lesson's own 267-million-year estimate assumes the recession rate stays fixed at today's 3.8 cm\u002Fyear for the entire span, which the fossil evidence in Deepen already showed is not exactly true — the rate itself has changed as Earth's continents rearranged the ocean tides that drive it. Treat the figure as showing *that* total eclipses have a finite future, and the right *order of magnitude* (hundreds of millions of years, not thousands or trillions), rather than a specific date to circle on a very long calendar.",{"id":389,"type":87,"caption":390,"columns":391,"rows":396},"ch5-day-length-table","The length of a day on Earth, then and now (fossil and tidal evidence)",[392,393,394,395],"When","Evidence","Approx. day length","Approx. Moon distance",[397,402,407,411],[398,399,400,401],"~4.5 billion years ago","Giant-impact formation models","A few hours","A small fraction of today's distance",[403,404,405,406],"~620 million years ago","Ediacaran tidal rhythmite rock layers","About 21.9 hours","Closer than today",[408,409,410,406],"~400 million years ago","Devonian fossil coral daily growth bands","About 22 hours",[412,413,414,415],"Today","Laser ranging to Apollo retroreflectors","24.0 hours","384,400 km (mean)",{"id":417,"type":47,"variant":418,"title":419,"markdown":420},"ch5-slowing-both-ways","aha","Two slowdowns, one shared cause","It is easy to think of \"Earth's day getting longer\" and \"the Moon drifting away\" as two separate facts you simply have to memorise. They are the *same* fact, described from two ends of one process: the tidal torque described in Deepen, Chapter 6 removes spin angular momentum from Earth (lengthening its day) and adds orbital angular momentum to the Moon (widening its orbit), because angular momentum in the whole Earth-Moon system is conserved. Slow the spinner down and something else in the system must speed up or move outward to compensate — here, the Moon's orbit does the compensating.",{"id":422,"type":47,"variant":423,"title":424,"markdown":425},"ch5-misconception-supermoon","misconception","“A 'supermoon' is a rare, dramatic event you can't miss”","It is neither especially rare nor dramatic to the naked eye. A perigee full moon happens several times most years (there is no single fixed definition of exactly how close counts), and Deepen's own calculation showed it looks only about 12% wider than an ordinary full moon — a difference most people cannot detect at all without a side-by-side photograph taken with the same lens and settings. The real, larger effect is on brightness (about 25% more light), which is also hard to judge by eye alone, since human vision does not perceive brightness on a simple linear scale. Media coverage often shows an exaggerated size comparison, or a photograph of the Moon low on the horizon (which triggers the separate Moon illusion), giving a stronger impression of drama than the underlying physics supports.",{"id":427,"type":78,"title":428,"eyebrow":429,"navLabel":430},"ch6","How other calendars solved the same problem","Chapter 06","6 Other calendars",{"id":432,"type":43,"markdown":433},"ch6-calendars","The Hindu lunisolar calendar's adhik maas is one solution to the mismatch between a lunar month and a solar year. It is far from the only one, and comparing solutions is a genuinely olympiad-flavoured way to test whether you understood *why* the problem exists in the first place.",{"id":435,"type":87,"caption":436,"columns":437,"rows":441},"ch6-calendar-compare","Three calendars, three answers to the same 10.9-day-a-year gap",[438,439,440],"Calendar","Strategy","Consequence",[442,446,450,454],[443,444,445],"Hindu lunisolar","Insert a whole adhik maas roughly every 3 years","Festivals stay anchored to the same season indefinitely, at the cost of an irregular calendar length",[447,448,449],"Islamic (Hijri)","No correction at all: 12 lunar months every year, always","The calendar drifts about 10.9 days earlier against the seasons every year, cycling through all of them roughly every 34 years",[451,452,453],"Hebrew","Insert a leap month in 7 of every 19 years (the Metonic cycle)","Very close long-term agreement with the solar year, similar in spirit to adhik maas but on a fixed 19-year schedule",[455,456,457],"Gregorian (solar only)","Ignores the Moon entirely; corrects only for the quarter-day-per-year solar mismatch with leap years","Months no longer track the actual Moon at all — a 'month' is just roughly 1\u002F12 of a year",{"id":459,"type":460,"itemId":461,"prompt":462,"check":463,"hints":467,"feedback":469},"practice-drift-cycle","practice","phases-of-the-moon.extend-drift-cycle","The Islamic calendar loses about 10.88 days a year against the solar year. To the nearest year, how long before a given Islamic month has drifted all the way through every season and returned to roughly the same solar date?",{"kind":464,"answer":465,"tolerance":5,"unit":466},"number",34,"years",[468],"Divide a full solar year (365.24 days) by the yearly drift.",{"correct":470,"incorrect":471},"Correct: 365.24 ÷ 10.88 ≈ **34 years**. This is why, over a person's lifetime, an Islamic-calendar month can fall in every season of the solar year in turn.","365.24 ÷ 10.88 ≈ 34 years.",{"id":473,"type":47,"variant":474,"title":475,"markdown":476},"ch6-no-right-answer","question","Is any one of these calendars 'better'?","Each solution trades off something. Adhik maas keeps festivals in the same season but makes the calendar irregular and needs an authority to decide exactly when to insert the extra month. The Hijri calendar is simple and needs no such authority, at the cost of no fixed link to the seasons at all (which for a purely religious calendar not tied to a harvest may not matter). The Gregorian calendar is administratively convenient worldwide but has completely severed 'month' from 'Moon'. There is no purely mathematical answer to which is 'best' — it depends on what a calendar is *for*.",{"id":478,"type":262,"conceptId":479,"relation":264,"explanation":480},"ch6-connect-government","government-india","Deciding when adhik maas falls, or officially declaring a sighting for Eid, both involve an authority making a calendar ruling that affects millions of people — a small but real example of institutions at work.",{"id":482,"type":78,"title":483,"eyebrow":484,"navLabel":485},"ch7","Puzzles","Chapter 07","7 Puzzles",{"id":487,"type":43,"markdown":488},"ch7-puzzles-intro","Five harder problems. Work them out before checking the worked solution style answers below each one.",{"id":490,"type":112,"title":491,"problem":492,"steps":493},"we-puzzle-lifetime-moons","Puzzle: how many full moons in a lifetime?","Estimate, to the nearest ten, how many full moons an 80-year-old person has lived through, assuming they saw every one.",[494,495,496],"There are about 12.37 synodic months (hence full moons) in a year.","Over 80 years: 12.37 × 80 ≈ **989 full moons**, to the nearest ten, about 990.","A nice way to sense-check: 80 years × 12 months\u002Fyear = 960 as a rough first guess using calendar months, and the true value is a little higher because a synodic month (29.53 days) is shorter than an average calendar month (30.44 days).",{"id":498,"type":47,"variant":48,"title":499,"markdown":500},"ch7-puzzle-tip","A general strategy for these puzzles","Every puzzle in this chapter reduces to the same three moves: identify which cycle length is relevant (a day, a synodic month, a tropical year, or one of the rarer cycles from Deepen), convert everything to the same unit, and divide. Resist the urge to guess from memory — these numbers are unforgiving of a half-remembered figure, and a wrong conversion early on will throw off everything that follows.",{"id":502,"type":87,"caption":503,"columns":504,"rows":507},"ch7-cycle-lengths","Every cycle length used across this topic, in one place",[505,506],"Cycle","Length",[508,511,514,517,520,523],[509,510],"Synodic month","29.53 days",[512,513],"Sidereal month","27.32 days",[515,516],"Draconic month","27.21 days",[518,519],"Tropical year","365.24 days",[521,522],"Metonic cycle","19 years (235 synodic months)",[524,525],"Saros cycle","18.03 years",{"id":527,"type":112,"title":528,"problem":529,"steps":530},"we-puzzle-node-return","Puzzle: eclipse seasons drift","Two eclipse seasons occur about 173.31 days apart, not exactly half a year (182.6 days) apart. Explain, in one or two sentences, why they do not land on the same two calendar dates every year.",[531,532,533],"Half of 346.62 days is 173.31 days, noticeably less than half a tropical year (182.62 days).","The shortfall, about 9.3 days each half-year, comes from the Moon's nodes themselves slowly rotating backwards around the Moon's orbit (a separate, roughly 18.6-year cycle), so the Sun reaches a node slightly sooner each time than a fixed half-year would predict.","This is why eclipse seasons visibly creep about three weeks earlier on the calendar every year, rather than recurring on the same date.",{"id":535,"type":460,"itemId":536,"prompt":537,"check":538,"hints":542,"feedback":544},"practice-puzzle-metonic-check","phases-of-the-moon.extend-metonic-check","235 synodic months last 6939.69 days. 19 tropical years last 6939.60 days. To the nearest tenth of a day, what is the difference between them?",{"kind":464,"answer":539,"tolerance":540,"unit":541},0.1,0.05,"days",[543],"Subtract the smaller total from the larger one.",{"correct":545,"incorrect":546},"Correct: 6939.69 − 6939.60 = **0.09 days**, under two and a half hours over nineteen years — an astonishingly close coincidence between two completely independent cycles.","6939.69 − 6939.60 ≈ 0.09 days.",{"id":548,"type":47,"variant":474,"title":549,"markdown":550},"ch7-puzzle-open","Puzzle without a clean numeric answer: design your own calendar","Suppose you had to design a new calendar for a colony on Mars, whose year is about 687 Earth-days long and whose two tiny moons, Phobos and Deimos, orbit far too fast (under eight hours and about 30 hours respectively) to give useful \"months\" at all. Would you keep any concept of a lunar month? What would you use to divide the Martian year into shorter periods instead, and why? There is no single correct answer — real Mars-calendar proposals exist and disagree with each other.",{"id":552,"type":78,"title":553,"eyebrow":554,"navLabel":555},"ch8","Who does this for a living","Chapter 08","8 Careers",{"id":557,"type":43,"markdown":558},"ch8-careers","Everything in this topic is somebody's actual job. A few examples, chosen to show the range.",{"id":560,"type":561,"title":562,"prompt":563,"options":564},"ch8-careers-explorer","explorer","Five ways to spend a career on this topic","Pick a path to see what a typical day involves.",[565,574,583,592,601],{"id":566,"label":567,"chain":568,"note":573},"panchang","Panchang maker",[569,570,571,572],"Astronomical calculation","Tithi, nakshatra, yoga tables","Print or app","Households and temples","A panchang-maker (traditionally a jyotishi or calendar astronomer) computes precise tithi, nakshatra and other astronomical quantities for each day of the year, publishing the almanacs that tell millions of households exactly when Purnima, Amavasya and festival dates fall. Modern versions are software, but the underlying calculation is the same elongation-based arithmetic in this topic, done to much higher precision.",{"id":575,"label":576,"chain":577,"note":582},"mission-scientist","ISRO mission scientist",[578,579,580,581],"Mission proposal","Instrument design","Launch and landing","Data analysis for years afterward","Scientists and engineers at ISRO spend years designing a single instrument, testing it against every failure mode they can imagine, then watching a landing they cannot control happen in real time, followed by years analysing the data it sends back. Chandrayaan-3's Pragyan rover returned soil composition data still being studied.",{"id":584,"label":585,"chain":586,"note":591},"geophysicist","Planetary geophysicist",[587,588,589,590],"Laser-ranging data","Orbital modelling","Recession rate refinement","Published papers","Researchers who study lunar laser-ranging data spend careers refining exactly how fast the Moon is receding, how Earth's rotation is slowing, and what that implies about the Earth-Moon system's deep past and future — the same physics in Deepen, Chapters 6 and 7, at research precision.",{"id":593,"label":594,"chain":595,"note":600},"calendar-reformer","Calendar historian",[596,597,598,599],"Historical calendars","Comparative astronomy","Proposals for reform","Public and religious debate","Historians and astronomers study how different cultures solved the lunar\u002Fsolar mismatch, and some have proposed calendar reforms (rarely adopted, because changing a widely used calendar is as much a social and political challenge as an astronomical one).",{"id":602,"label":603,"chain":604,"note":609},"science-communicator","Science communicator",[605,606,607,608],"Public curiosity","Explaining phases and eclipses","Planetarium shows, videos, books","Correcting the shadow myth","Someone has to explain all of this clearly to the public — correcting the shadow misconception, explaining why eclipses are rare, translating a research paper on lunar recession into something a school class can follow. That is its own skilled profession.",{"id":611,"type":78,"title":612,"eyebrow":613,"navLabel":614},"ch9","Open questions","Chapter 09","9 Open questions",{"id":616,"type":47,"variant":474,"title":617,"markdown":618},"ch9-open-questions","Nobody has fully answered these yet","Pick one and find out how far current research has actually got.\n\n- Why does the near side have so many more dark maria than the far side — is the leading \"thicker far-side crust\" explanation the whole story, or is something else involved?\n- Exactly how much water ice sits in the Moon's permanently shadowed craters, and is it concentrated enough to be worth extracting with realistic engineering?\n- What causes the \"Moon illusion\" that makes a horizon Moon look larger than an overhead one, when careful measurement shows its angular size barely changes?\n- If humans build a permanent base near the lunar south pole, whose water ice is it, and who decides how it is shared? (International space law is still unsettled on many such questions.)\n- How precisely has the Moon's recession rate varied over the last few hundred million years as Earth's continents drifted, and can that history be reconstructed from rock and fossil evidence alone?\n- Could a future Mars-like colony on the Moon itself ever develop its own local calendar, given that \"a day\" there already means something different (an Earth-length lunar day-night cycle rather than one Earth-rotation)?",{"id":620,"type":621,"title":622,"terms":623},"ch9-glossary","glossary","New vocabulary in this layer",[624,628,632,636,640,644,648],{"term":625,"meaning":626,"example":627},"Libration","A small, real wobble in the Moon's orientation as seen from Earth, letting slightly more than half its surface become visible over time.","Longitude libration reaches about 7.9 degrees each way.",{"term":629,"meaning":630,"example":631},"Far side","The hemisphere of the Moon that never faces Earth — not darker than the near side, just permanently turned away.","Luna 3 took the first photographs of the far side in 1959.",{"term":633,"meaning":634,"example":635},"Permanently shadowed crater","A polar crater deep enough that its floor never receives direct sunlight, because of the Moon's very small axial tilt.","These cold traps are the leading candidate sites for lunar water ice.",{"term":637,"meaning":638,"example":639},"Statio Shiv Shakti","The name given to Chandrayaan-3's Vikram lander touchdown site near the lunar south pole.","Named after the 2023 landing that made India the first country to land so close to the pole.",{"term":641,"meaning":642,"example":643},"Tidal rhythmite","A layered sedimentary rock formation that preserves a daily and monthly record of ancient tides, used to infer past day length.","Ediacaran-period rhythmites suggest a roughly 21.9-hour day about 620 million years ago.",{"term":645,"meaning":646,"example":647},"Lunisolar calendar","A calendar that keeps lunar months but periodically inserts an extra month to stay aligned with the solar year.","The Hindu calendar and the Hebrew calendar are both lunisolar.",{"term":649,"meaning":650,"example":651},"Cold trap","A permanently shadowed, extremely cold region where volatile substances such as water ice can survive for very long periods without evaporating.","The floors of some lunar polar craters act as cold traps.",{"id":653,"type":654,"prompt":655},"reflect-extend","reflection","Choose one open question from this chapter. Write down what you would need to learn, measure or build in order to make even a small amount of progress on it yourself, and be honest about which parts are within your reach right now and which parts are not.",{"id":657,"type":262,"conceptId":658,"relation":659,"explanation":660},"connect-eclipses-ext","eclipses","helps_understand","The 5.1-degree tilt, the Saros cycle and the future end of totality all connect directly into the full mechanics of eclipses covered there.",{"id":662,"type":262,"conceptId":263,"relation":264,"explanation":663},"connect-exploration-ext","Chandrayaan-3, the race for lunar water ice, and the unanswered legal questions about who owns it are a modern continuation of the same reasons-and-consequences pattern seen in Earth's own age of exploration.",{"id":665,"type":666,"title":667,"questions":668},"quiz-extend","quiz","Test yourself at the edges of the topic",[669,681,692,701,714,727,740,753],{"itemId":670,"prompt":671,"options":672,"correct":309,"why":680},"phases-of-the-moon.extend-q-libration-pct","What fraction of the Moon's surface becomes visible from Earth at some point, thanks to libration?",[673,675,676,678],{"id":306,"label":674},"50%",{"id":309,"label":58},{"id":312,"label":677},"75%",{"id":315,"label":679},"100%","Libration in longitude and latitude together let us peek round the edges at different times, raising the total ever-visible fraction from a plain 50% to about 59%.",{"itemId":682,"prompt":683,"options":684,"correct":309,"why":691},"phases-of-the-moon.extend-q-libration-once","At any single instant, how much of the Moon can you actually see?",[685,686,688,689],{"id":306,"label":58},{"id":309,"label":687},"Very close to a true half, about 50%",{"id":312,"label":679},{"id":315,"label":690},"It depends only on the season","The 59% figure is a total collected over months of observing, not a single view. At any given moment you still see close to one true half.",{"itemId":693,"prompt":694,"options":695,"correct":312,"why":700},"phases-of-the-moon.extend-q-farside-first","Which mission first photographed the Moon's far side?",[696,697,698,699],{"id":306,"label":164},{"id":309,"label":176},{"id":312,"label":160},{"id":315,"label":172},"Luna 3, a Soviet probe, returned the first far-side photographs in 1959, nearly a decade before Apollo 8's crew saw it with their own eyes.",{"itemId":702,"prompt":703,"options":704,"correct":309,"why":713},"phases-of-the-moon.extend-q-ch3-lifetime","Why was Chandrayaan-3's Vikram lander designed for about one lunar day of operation?",[705,707,709,711],{"id":306,"label":706},"It ran on a battery with a fixed charge",{"id":309,"label":708},"It was solar-powered, and the roughly two-week lunar night that follows is dark and extremely cold",{"id":312,"label":710},"ISRO wanted a short mission on purpose",{"id":315,"label":712},"The rover needed to return to Earth","Vikram and Pragyan drew power from sunlight. Once the roughly 15-day lunar night fell, there was no power and extreme cold to survive, so the mission's working life was tied to a single lunar day.",{"itemId":715,"prompt":716,"options":717,"correct":309,"why":726},"phases-of-the-moon.extend-q-southpole-tilt","Which of the Moon's two tilts explains permanently shadowed polar craters?",[718,720,722,724],{"id":306,"label":719},"The 5.145° orbital tilt",{"id":309,"label":721},"The small, 1.5424° axial tilt",{"id":312,"label":723},"Both equally",{"id":315,"label":725},"Neither; it is caused by the Moon's distance from the Sun","The Moon's axial tilt is so small that sunlight grazes the poles at a nearly constant, extremely shallow angle, letting some deep crater floors stay in permanent shadow.",{"itemId":728,"prompt":729,"options":730,"correct":312,"why":739},"phases-of-the-moon.extend-q-drift-cycle","About how many years does it take the Islamic calendar to drift through every season and back?",[731,733,735,737],{"id":306,"label":732},"About 3 years",{"id":309,"label":734},"About 11 years",{"id":312,"label":736},"About 34 years",{"id":315,"label":738},"It never drifts","Losing about 10.9 days a year against the solar year, a full cycle through all the seasons takes roughly 34 years.",{"itemId":741,"prompt":742,"options":743,"correct":309,"why":752},"phases-of-the-moon.extend-q-eclipse-end","Why will total solar eclipses eventually stop happening at all, on a scale of hundreds of millions of years?",[744,746,748,750],{"id":306,"label":745},"The Sun is shrinking",{"id":309,"label":747},"The Moon is receding, so its apparent size will eventually always be smaller than the Sun's even at closest approach",{"id":312,"label":749},"Earth's orbit is shrinking",{"id":315,"label":751},"The Moon will be destroyed","As the Moon recedes it looks smaller. Once even its closest approach (perigee) makes it look smaller than the Sun, no alignment can produce a total eclipse any more, only annular ones.",{"itemId":754,"prompt":755,"options":756,"correct":309,"why":765},"phases-of-the-moon.extend-q-farside-maria","Why does the Moon's far side have far fewer maria (dark lava plains) than the near side?",[757,759,761,763],{"id":306,"label":758},"The far side gets no sunlight",{"id":309,"label":760},"The leading explanation is a thicker far-side crust that ancient lava struggled to break through, though this remains an active research question",{"id":312,"label":762},"Meteors only strike the near side",{"id":315,"label":764},"Maria only form near Earth's shadow","A thicker far-side crust is the leading explanation, but exactly why the crust differs is still being researched — a genuinely open question, not a fully settled one.",{"id":767,"type":768,"title":769,"points":770},"cheat-sheet-extend","summary","Extend cheat sheet",[771,772,773,774,775,776,777,778,779,780],"**Libration lets 59% of the Moon become visible over time**, never more than close to 50% at any single instant.","**\"Far side\" is correct; \"dark side\" is a myth** — every part of the Moon gets roughly two weeks of sunlight and two of darkness each month.","**Luna 3 (1959) first photographed the far side; Apollo 8 (1968) first saw it directly; Chang'e-4 (2019) first landed there.**","**Chandrayaan-3's Vikram lander touched down on 23 August 2023** near 69.373° S, at Statio Shiv Shakti, marked annually as National Space Day.","**The tiny 1.5424° axial tilt, not the 5.145° orbital tilt, causes permanently shadowed polar craters** that may hold water ice.","**Chandrayaan-1 (2008-09) first detected water\u002Fhydroxyl on the Moon**; LCROSS (2009) then confirmed water ice in a shadowed crater by deliberately crashing into it.","**The Moon was once much closer and Earth's day much shorter**; both fossil coral bands and laser ranging agree on a slowing Earth and a receding Moon.","**A rough estimate puts the end of total solar eclipses hundreds of millions of years from now** (this lesson's own calculation: about 267 million years), as the Moon's apparent size keeps shrinking.","**Different calendars solve the lunar\u002Fsolar mismatch differently**: adhik maas (Hindu), no correction at all (Islamic, drifting through the seasons over about 34 years), a fixed 19-year cycle (Hebrew), or ignoring the Moon (Gregorian).","**Several genuinely open questions remain**, from the cause of the near\u002Ffar side difference to who owns lunar water ice — this is an active field, not a closed book.",{"id":782,"type":783,"sourceIds":784},"sources-extend","sources",[785,786,787,788,789,790,791,792,793,794,795,796],"phases-of-the-moon-nasa-svs-libration","phases-of-the-moon-wikipedia-far-side","phases-of-the-moon-isro-chandrayaan3","phases-of-the-moon-wikipedia-chandrayaan1","phases-of-the-moon-nssdc-apollo-llr","phases-of-the-moon-wikipedia-earth-rotation","phases-of-the-moon-wikipedia-islamic-calendar","phases-of-the-moon-wikipedia-metonic","phases-of-the-moon-wikipedia-solar-eclipse","phases-of-the-moon-nasa-moon-facts","phases-of-the-moon-wikipedia-luna25","phases-of-the-moon-wikipedia-artemis",[785,786,787,788,789,790,791,792,793,794,795,796],"needs_review",{"generatedBy":800,"notes":801},"claude-code","Draft generated locally; pending owner review. Libration fractions, Chandrayaan-3 lunar-day length, eclipse-cessation estimate, calendar drift cycle and Metonic check all computed and asserted in numbers.py.","50039800960ffd410368b4a875cc1d29dc0be027640dc8315b3eae66d3d8067b",{"component:moon-phase@1":804,"component:match-pairs@1":805,"component:sort-game@1":806,"logic:practice":807,"source:phases-of-the-moon-isro-chandrayaan3":808,"source:phases-of-the-moon-nasa-moon-facts":809,"source:phases-of-the-moon-nasa-svs-libration":810,"source:phases-of-the-moon-nssdc-apollo-llr":811,"source:phases-of-the-moon-wikipedia-artemis":812,"source:phases-of-the-moon-wikipedia-chandrayaan1":813,"source:phases-of-the-moon-wikipedia-earth-rotation":814,"source:phases-of-the-moon-wikipedia-far-side":815,"source:phases-of-the-moon-wikipedia-islamic-calendar":816,"source:phases-of-the-moon-wikipedia-luna25":817,"source:phases-of-the-moon-wikipedia-metonic":818,"source:phases-of-the-moon-wikipedia-solar-eclipse":819},"39afeb0bba7518b8118317655457b27214a4a2a315d236762bf1d6a6a40e18f3","2a8ee4ac87460b4e1175a4bb13c96b03d577db06dde95670eb7fcfe4ad787899","b164f45a2c8ca08f26c450768ff0231e113e9fe45381eddb34dc6d0548596c38","3d6b0fe1b15255975a32b0fcd94e8019bc959ad45cbf12e136e86149549c6878","6add9b81691e662b3e30f5adf80290aa1891a8306c87ea2ce4c65fa718077468","42fce1fa13db44246876ac36bd3506964da8f7fa12ecfcb17813905e4161b696","e28faaf9d6da287ce1cdb3b7a69399f9bd6eb3488f41f10fb1ad71da7869c299","15d68c7c8e7c5840ddb4a445227372b32238fff4b4f20713e7baaba612edfac4","a4215945dabf52e73799b6b08078c54ec2b193487858753041eb80f2430ca74a","096b677bf4fe49d122a737e7e67e06fedd219ef31662c7c3525e759d41ae6ebb","86a66e5f8cfccd44595a6b41c9e2006fe2e7df776f1bbd9554460c01fd1b1589","4633fdef7574b37ecc72efb816ad59a035dab48d636fa85f09321f96d5c71b64","6466bf563754245e0228dcb19bb51f7b1569935d0f79b49ca74667b3727986d5","13ec7b85e5132ceeb37b1338ad7f0048fab2a662f68168921bd4b8fb60598ed4","ff896ce117e280c010af398964069ef2b9b24b3830e68d6b888f21517aba63b8","a46a1f97f6c0957af656877407a705313520bd50bca437aa84f57736501e3621",{"state":821,"reviewer":822,"selfReview":823,"reviewedAt":824,"method":825},"approved","The library owner",true,"2026-09-20T10:18:37.581Z","owner_bulk","preview-7e1cbbcc4f",1789899598596]