1 files changed, 8 insertions, 927 deletions

diff --git a/CosmicCalendar.hs b/CosmicCalendar.hs
index 5e7ef4a..bab94da 100644
--- a/CosmicCalendar.hs
+++ b/CosmicCalendar.hs
@@ -75,9 +75,6 @@ data CalendarEntry = CalendarEntry {
 currentYear :: Integer
 currentYear = unsafePerformIO $ getZonedTime <&> toGregorian . localDay . zonedTimeToLocalTime <&> view _1
 
-theCalendar :: Map NominalDiffTime CalendarEntry
-theCalendar = Map.fromList $ map (\x -> (calBeginTime x, x)) theCalendarList
-
 years :: Rational -> NominalDiffTime
 years = (* lengthOfYear) . fromRational
 
@@ -115,14 +112,16 @@ yearStart (LocalTime d _) = LocalTime d' t'
 localTimeToYearElapsed :: LocalTime -> NominalDiffTime
 localTimeToYearElapsed t = t `diffLocalTime` yearStart t
 
-getPreviousCalendarEntry :: LocalTime -> Maybe CalendarEntry
-getPreviousCalendarEntry (localTimeToYearElapsed -> t) = snd <$> Map.lookupLT t theCalendar
+getPreviousCalendarEntry :: Calendar -> LocalTime -> Maybe CalendarEntry
+getPreviousCalendarEntry cal (localTimeToYearElapsed -> t) = snd <$> Map.lookupLT t cal
+
+getCurrentCalendarEntry :: Calendar -> LocalTime -> Maybe CalendarEntry
+getCurrentCalendarEntry cal (localTimeToYearElapsed -> t) = snd <$> Map.lookupLE t cal
 
-getCurrentCalendarEntry :: LocalTime -> Maybe CalendarEntry
-getCurrentCalendarEntry (localTimeToYearElapsed -> t) = snd <$> Map.lookupLE t theCalendar
+type Calendar = Map NominalDiffTime CalendarEntry
 
-getNextCalendarEntry :: LocalTime -> Maybe CalendarEntry
-getNextCalendarEntry (localTimeToYearElapsed -> t) = snd <$> Map.lookupGT t theCalendar
+getNextCalendarEntry :: Calendar -> LocalTime -> Maybe CalendarEntry
+getNextCalendarEntry cal (localTimeToYearElapsed -> t) = snd <$> Map.lookupGT t cal
 
 unwrap :: CalendarEntry -> CalendarEntry
 unwrap x@CalendarEntry{..} = x { calDescription = unwrapText calDescription }
@@ -136,921 +135,3 @@ unwrap x@CalendarEntry{..} = x { calDescription = unwrapText calDescription }
     shouldMerge "" _ = False
     shouldMerge _ "" = False
     shouldMerge _ _  = True
-
-theCalendarList :: [CalendarEntry]
-theCalendarList = map unwrap
-  [
-    CalendarEntry 0 Nothing "The Big Bang" "The universe begins" "" "",
-    CalendarEntry (370 & thousandYears & afterBigBang)
-                  Nothing
-                  "Recombination"
-                  "The universe becomes transparent"
-                  recombinationDescription
-                  recombinationReferences,
-    CalendarEntry (13.4 & billionYearsAgo) Nothing
-    "The first observed star"
-    ""
-    "First Light Viewed Through the Rich Cluster Abell 2218"
-    "https://sites.astro.caltech.edu/~rse/firstlight/",
-    CalendarEntry (4.6 & billionYearsAgo) Nothing
-    "Formation of the Sun"
-    "The formation of the solar system begins"
-    [text|
-    The formation of the Solar System began about 4.6 billion years ago with the
-    gravitational collapse of a small part of a giant molecular cloud.[1] Most
-    of the collapsing mass collected in the center, forming the Sun, while the
-    rest flattened into a protoplanetary disk out of which the planets, moons,
-    asteroids, and other small Solar System bodies formed.
-    |]
-    "https://en.wikipedia.org/wiki/Formation_and_evolution_of_the_Solar_System",
-    CalendarEntry (4.54 & billionYearsAgo) Nothing
-    "Formation of Earth"
-    ""
-    earthDescription
-    "https://en.wikipedia.org/wiki/History_of_Earth#Solar_System_formation",
-
-    CalendarEntry (2.6 & millionYearsAgo) Nothing
-    "First Stone Tools"
-    "Mode I: The Oldowan Industry"
-    [text|
-    (Stones with sharp edges.)
-
-    The earliest known Oldowan tools yet found date from 2.6 million years ago,
-    during the Lower Palaeolithic period, and have been uncovered at Gona in
-    Ethiopia.[16] After this date, the Oldowan Industry subsequently spread
-    throughout much of Africa, although archaeologists are currently unsure
-    which Hominan species first developed them, with some speculating that it
-    was Australopithecus garhi, and others believing that it was in fact Homo
-    habilis.[17]
-
-    Homo habilis was the hominin who used the tools for most of the Oldowan in
-    Africa, but at about 1.9-1.8 million years ago Homo erectus inherited them.
-    The Industry flourished in southern and eastern Africa between 2.6 and 1.7
-    million years ago, but was also spread out of Africa and into Eurasia by
-    travelling bands of H. erectus, who took it as far east as Java by 1.8
-    million years ago and Northern China by 1.6 million years ago.
-    |]
-    "",
-
-    CalendarEntry (1.8 & millionYearsAgo) Nothing
-    "First major transition in stone tool technology"
-    "Mode II: The Acheulean Industry"
-    [text|
-    From the Konso Formation of Ethiopia, Acheulean hand-axes are dated to about
-    1.5 million years ago using radiometric dating of deposits containing
-    volcanic ashes.[6] Acheulean tools in South Asia have also been found to be
-    dated as far as 1.5 million years ago.[7] However, the earliest accepted
-    examples of the Acheulean currently known come from the West Turkana region
-    of Kenya and were first described by a French-led archaeology team.[8] These
-    particular Acheulean tools were recently dated through the method of
-    magnetostratigraphy to about 1.76 million years ago, making them the oldest
-    not only in Africa but the world.[9] The earliest user of Acheulean tools
-    was Homo ergaster, who first appeared about 1.8 million years ago. Not all
-    researchers use this formal name, and instead prefer to call these users
-    early Homo erectus.[3]
-    |]
-    "",
-
-    CalendarEntry (160 & thousandYearsAgo) Nothing
-    "Second major transition in stone tool technology"
-    "Mode III: The Levallois technique; The Mousterian Industry"
-    [text|
-    (Stone scrapers, knives, and projectile points)
-
-    The technique is first found in the Lower Palaeolithic but is most commonly
-    associated with the Neanderthal Mousterian industries of the Middle
-    Palaeolithic. In the Levant, the Levallois technique was also used by
-    anatomically modern humans during the Middle Stone Age. In North Africa, the
-    Levallois technique was used in the Middle Stone Age, most notably in the
-    Aterian industry to produce very small projectile points. While Levallois
-    cores do display some variability in their platforms, their flake production
-    surfaces show remarkable uniformity. As the Levallois technique is
-    counterintuitive, teaching the process is necessary and thus language is a
-    prerequisite for such technology.[2]
-
-    The Mousterian (or Mode III) is a techno-complex (archaeological industry)
-    of stone tools, associated primarily with the Neanderthals in Europe, and to
-    a lesser extent the earliest anatomically modern humans in North Africa and
-    West Asia. The Mousterian largely defines the latter part of the Middle
-    Paleolithic, the middle of the West Eurasian Old Stone Age. It lasted
-    roughly from 160,000 to 40,000 BP. If its predecessor, known as Levallois or
-    Levallois-Mousterian, is included, the range is extended to as early as c.
-    300,000–200,000 BP.[2] The main following period is the Aurignacian (c.
-    43,000–28,000 BP) of Homo sapiens.
-    |]
-    "",
-
-    CalendarEntry (115 & thousandYearsAgo) (Just $ 11.7 & thousandYearsAgo)
-    "The Ice Age begins"
-    "The Last Glacial Period"
-    [text|
-    The Last Glacial Period (LGP), also known colloquially as the last ice age
-    or simply ice age,[1] occurred from the end of the Eemian to the end of the
-    Younger Dryas, encompassing the period c. 115,000 – c. 11,700 years ago. The
-    LGP is part of a larger sequence of glacial and interglacial periods known
-    as the Quaternary glaciation which started around 2,588,000 years ago and is
-    ongoing.[2] The definition of the Quaternary as beginning 2.58 million years
-    ago (Mya) is based on the formation of the Arctic ice cap. The Antarctic ice
-    sheet began to form earlier, at about 34 Mya, in the mid-Cenozoic
-    (Eocene–Oligocene extinction event). The term Late Cenozoic Ice Age is used
-    to include this early phase.[3]
-    |]
-    "https://en.wikipedia.org/wiki/Last_Glacial_Period",
-
-    CalendarEntry (50 & thousandYearsAgo) Nothing
-    "Third major transition in stone tool technology"
-    "Mode IV: The Aurignacian Industry"
-    [text|
-    The widespread use of long blades (rather than flakes) of the Upper
-    Palaeolithic Mode 4 industries appeared during the Upper Palaeolithic
-    between 50,000 and 10,000 years ago, although blades were produced in small
-    quantities much earlier by Neanderthals.[20] The Aurignacian culture seems
-    to have been the first to rely largely on blades.[21] The use of blades
-    exponentially increases the efficiency of core usage compared to the
-    Levallois flake technique, which had a similar advantage over Acheulean
-    technology which was worked from cores.
-    |]
-    "https://en.wikipedia.org/wiki/Stone_tool#Mode_IV:_The_Aurignacian_Industry",
-
-    CalendarEntry (35 & thousandYearsAgo) Nothing
-    "Last major transition in stone tool technology"
-    "Mode V: The Microlithic Industries"
-    [text|
-    Mode 5 stone tools involve the production of microliths, which were
-    used in composite tools, mainly fastened to a shaft.[22] Examples include
-    the Magdalenian culture. Such a technology makes much more efficient use of
-    available materials like flint, although required greater skill in
-    manufacturing the small flakes. Mounting sharp flint edges in a wood or bone
-    handle is the key innovation in microliths, essentially because the handle
-    gives the user protection against the flint and also improves leverage of
-    the device.
-    |]
-    "https://en.wikipedia.org/wiki/Stone_tool#Mode_V:_The_Microlithic_Industries"
-    ,
-
-    CalendarEntry (12 & thousandYearsAgo) Nothing
-    "Agriculture leads to permanent settlements"
-    "Neolithic age (\"new stone age\")"
-    [text|
-    Wild grains were collected and eaten from at least 105,000 years ago.[2]
-    However, domestication did not occur until much later. The earliest evidence
-    of small-scale cultivation of edible grasses is from around 21,000 BC with
-    the Ohalo II people on the shores of the Sea of Galilee.[3] By around 9500
-    BC, the eight Neolithic founder crops – emmer wheat, einkorn wheat, hulled
-    barley, peas, lentils, bitter vetch, chickpeas, and flax – were cultivated
-    in the Levant.[4] Rye may have been cultivated earlier, but this claim
-    remains controversial.[5] Rice was domesticated in China by 6200 BC[6] with
-    earliest known cultivation from 5700 BC, followed by mung, soy and azuki
-    beans. Rice was also independently domesticated in West Africa and
-    cultivated by 1000 BC.[7][8] Pigs were domesticated in Mesopotamia around
-    11,000 years ago, followed by sheep. Cattle were domesticated from the wild
-    aurochs in the areas of modern Turkey and India around 8500 BC. Camels were
-    domesticated late, perhaps around 3000 BC.
-    |]
-    "https://en.wikipedia.org/wiki/History_of_agriculture",
-
-    CalendarEntry (6.5 & thousandYearsAgo) Nothing
-    "First copper tools"
-    ""
-    ""
-    "",
-
-    CalendarEntry (5.3 & thousandYearsAgo) Nothing
-    "First bronze tools, first written language"
-    "The Bronze Age"
-    ""
-    "",
-
-    CalendarEntry (3000 & yearsBeforeCommonEra) (Just $ 2350 & yearsBeforeCommonEra)
-    "Corded Ware culture"
-    "Indo-European languages spread across Europe and Asia"
-    [text|
-    The Corded Ware culture comprises a broad archaeological horizon of Europe
-    between ca. 3000 BCE – 2350 BCE, thus from the late Neolithic, through the
-    Copper Age, and ending in the early Bronze Age.[2] Corded Ware culture
-    encompassed a vast area, from the contact zone between the Yamnaya culture
-    and the Corded Ware culture in south Central Europe, to the Rhine on the
-    west and the Volga in the east, occupying parts of Northern Europe, Central
-    Europe and Eastern Europe.[2][3] The Corded Ware culture is thought to have
-    originated from the westward migration of Yamnaya-related people from the
-    steppe-forest zone into the territory of late Neolithic European cultures
-    such as the Globular Amphora and Funnelbeaker cultures,[4][5][6] and is
-    considered to be a likely vector for the spread of many of the Indo-European
-    languages in Europe and Asia.[1][7][8][9]
-
-    Corded Ware encompassed most of continental northern Europe from the Rhine
-    on the west to the Volga in the east, including most of modern-day Germany,
-    the Netherlands, Denmark, Poland, Lithuania, Latvia, Estonia, Belarus, Czech
-    Republic, Austria, Hungary, Slovakia, Switzerland, northwestern Romania,
-    northern Ukraine, and the European part of Russia, as well as coastal Norway
-    and the southern portions of Sweden and Finland.[2] In the Late
-    Eneolithic/Early Bronze Age, it encompassed the territory of nearly the
-    entire Balkan Peninsula, where Corded Ware mixed with other steppe
-    elements.[11]
-
-    Archaeologists note that Corded Ware was not a "unified culture," as Corded
-    Ware groups inhabiting a vast geographical area from the Rhine to Volga seem
-    to have regionally specific subsistence strategies and economies.[2]: 226 
-    There are differences in the material culture and in settlements and
-    society.[2] At the same time, they had several shared elements that are
-    characteristic of all Corded Ware groups, such as their burial practices,
-    pottery with "cord" decoration and unique stone-axes.[2]
-    |]
-    "",
-
-    CalendarEntry (2800 & yearsBeforeCommonEra) (Just $ 1800 & yearsBeforeCommonEra)
-    "Bell Beaker culture"
-    [text|
-    copper daggers, v-perforated buttons, stone wrist-guards
-    copper, bronze, and gold working
-    long-distance exchange networks, archery
-    social stratification and the emergence of regional elites
-    |]
-    [text|
-    The Bell Beaker culture (also described as the Bell Beaker complex or Bell
-    Beaker phenomenon) is an archaeological culture named after the
-    inverted-bell beaker drinking vessel used at the very beginning of the
-    European Bronze Age. Arising from around 2800 BC, it lasted in Britain until
-    as late as 1800 BC[1][2] but in continental Europe only until 2300 BC, when
-    it was succeeded by the Unetice culture. The culture was widely dispersed
-    throughout Western Europe, being present in many regions of Iberia and
-    stretching eastward to the Danubian plains, and northward to the islands of
-    Great Britain and Ireland, and was also present in the islands of Sicily and
-    Sardinia and some small coastal areas in north-western Africa. The Bell
-    Beaker phenomenon shows substantial regional variation, and a study[3] from
-    2018 found that it was associated with genetically diverse populations.
-
-    In its mature phase, the Bell Beaker culture is understood as not only a
-    collection of characteristic artefact types, but a complex cultural
-    phenomenon involving metalwork in copper and gold, long-distance exchange
-    networks, archery, specific types of ornamentation, and (presumably) shared
-    ideological, cultural and religious ideas, as well as social stratification
-    and the emergence of regional elites.[6][7] A wide range of regional
-    diversity persists within the widespread late Beaker culture, particularly
-    in local burial styles (including incidences of cremation rather than
-    burial), housing styles, economic profile, and local ceramic wares
-    (Begleitkeramik). Nonetheless, according to Lemercier (2018) the mature
-    phase of the Beaker culture represents "the appearance of a kind of Bell
-    Beaker civilization of continental scale."[8]
-
-    Bell Beaker people took advantage of transport by sea and rivers, creating a
-    cultural spread extending from Ireland to the Carpathian Basin and south
-    along the Atlantic coast and along the Rhône valley to Portugal, North
-    Africa, and Sicily, even penetrating northern and central Italy.[50] Its
-    remains have been found in what is now Portugal, Spain, France (excluding
-    the central massif), Ireland and Great Britain, the Low Countries and
-    Germany between the Elbe and Rhine, with an extension along the upper Danube
-    into the Vienna Basin (Austria), Hungary and the Czech Republic, with
-    Mediterranean outposts on Sardinia and Sicily; there is less certain
-    evidence for direct penetration in the east.
-    |]
-    "https://en.wikipedia.org/wiki/Bell_Beaker_culture",
-
-    CalendarEntry (11.7 & thousandYearsAgo) Nothing
-    "Ice Age ends"
-    ""
-    ""
-    "https://en.wikipedia.org/wiki/Last_Glacial_Period",
-
-    CalendarEntry (1600 & yearsBeforeCommonEra) Nothing
-    "Dynastic China"
-    "History begins"
-    [text|
-    The earliest known written records of the history of China date from as
-    early as 1250 BC, from the Shang dynasty (c. 1600–1046 BC), during the king
-    Wu Ding's reign
-
-    The state-sponsored Xia–Shang–Zhou Chronology Project dated them from c.
-    1600 to 1046 BC based on the carbon 14 dates of the Erligang site.
-    |]
-    "",
-
-    CalendarEntry (theYear 1492) Nothing
-    "Columbus arrives in America"
-    ""
-    ""
-    "",
-
-    CalendarEntry (theYear 570) Nothing
-    "Muhammad born"
-    ""
-    ""
-    "",
-
-    CalendarEntry (480 & yearsBeforeCommonEra) Nothing
-    "Old Testament, Buddha"
-    ""
-    ""
-    "",
-
-    CalendarEntry (8.8 & billionYearsAgo) Nothing
-    "Thin disk of the Milky Way Galaxy"
-    "Our galaxy begins to form"
-    [text|
-    The age of stars in the galactic thin disk has also been estimated using
-    nucleocosmochronology. Measurements of thin disk stars yield an estimate
-    that the thin disk formed 8.8 ± 1.7 billion years ago. These measurements
-    suggest there was a hiatus of almost 5 billion years between the formation
-    of the galactic halo and the thin disk.[253] Recent analysis of the chemical
-    signatures of thousands of stars suggests that stellar formation might have
-    dropped by an order of magnitude at the time of disk formation, 10 to 8
-    billion years ago, when interstellar gas was too hot to form new stars at
-    the same rate as before.[254]
-    |]
-    "",
-
-    CalendarEntry (3.4 & billionYearsAgo) Nothing
-    "First photosynthetic bacteria"
-    "(Still no Oxygen)"
-    [text|
-    They absorbed near-infrared rather than visible light and produced sulfur or
-    sulfate compounds rather than oxygen. Their pigments (possibly
-    bacteriochlorophylls) were predecessors to chlorophyll.
-    |]
-    "https://www.scientificamerican.com/article/timeline-of-photosynthesis-on-earth/",
-
-    CalendarEntry (2.7 & billionYearsAgo) Nothing
-    "Oxygen from photosynthesis"
-    "Cyanobacteria"
-    [text|
-    These ubiquitous bacteria were the first oxygen producers. They absorb
-    visible light using a mix of pigments: phycobilins, carotenoids and several
-    forms of chlorophyll.
-    |]
-    "https://www.scientificamerican.com/article/timeline-of-photosynthesis-on-earth/",
-
-    CalendarEntry (1.2 & billionYearsAgo) Nothing
-    "Red and brown algae"
-    ""
-    [text|
-    These organisms have more complex cellular structures than bacteria do. Like
-    cyanobacteria, they contain phycobilin pigments as well as various forms of
-    chlorophyll.
-    |]
-    "https://www.scientificamerican.com/article/timeline-of-photosynthesis-on-earth/",
-
-    CalendarEntry (0.75 & billionYearsAgo) Nothing
-    "Green algae"
-    ""
-    [text|
-    Green algae do better than red and brown algae in the strong light of
-    shallow water. They make do without phycobilins.
-    |]
-    "https://www.scientificamerican.com/article/timeline-of-photosynthesis-on-earth/",
-
-    CalendarEntry (0.475 & billionYearsAgo) Nothing
-    "First land plants"
-    ""
-    [text|
-    Mosses and liverworts descended from green algae. Lacking vascular structure
-    (stems and roots) to pull water from the soil, they are unable to grow
-    tall.
-    |]
-    "https://www.scientificamerican.com/article/timeline-of-photosynthesis-on-earth/",
-
-    CalendarEntry (0.423 & billionYearsAgo) Nothing
-    "Vascular plants"
-    ""
-    [text|
-    These are literally garden-variety plants, such as ferns, grasses, trees and
-    cacti. They are able to grow tall canopies to capture more light.
-    |]
-    "https://www.scientificamerican.com/article/timeline-of-photosynthesis-on-earth/",
-
-    CalendarEntry (2.05 & billionYearsAgo) Nothing
-    "Eukaryotic cells"
-    "Cells with nucleus (inner membrane holding DNA)"
-    [text|
-    Eukaryotes (/juːˈkærioʊts, -əts/) are organisms whose cells have a nucleus
-    enclosed within a nuclear envelope.[1][2][3] They belong to the group of
-    organisms Eukaryota or Eukarya; their name comes from the Greek εὖ (eu,
-    "well" or "good") and κάρυον (karyon, "nut" or "kernel").[4] The domain
-    Eukaryota makes up one of the three domains of life; bacteria and archaea
-    (both prokaryotes) make up the other two domains.[5][6] The eukaryotes are
-    usually now regarded as having emerged in the Archaea or as a sister of the
-    Asgard archaea.[7][8] This implies that there are only two domains of life,
-    Bacteria and Archaea, with eukaryotes incorporated among archaea.[9][10]
-    Eukaryotes represent a small minority of the number of organisms;[11]
-    however, due to their generally much larger size, their collective global
-    biomass is estimated to be about equal to that of prokaryotes.[11]
-    Eukaryotes emerged approximately 2.3–1.8 billion years ago, during the
-    Proterozoic eon, likely as flagellated phagotrophs.[12][13]
-    |]
-    "https://en.wikipedia.org/wiki/Eukaryote",
-
-    CalendarEntry (3.77 & billionYearsAgo) Nothing
-    "Life on Earth"
-    ""
-    [text|
-    The earliest time for the origin of life on Earth is at least 3.77 billion
-    years ago, possibly as early as 4.28 billion years,[2] or even 4.41 billion
-    years[4][5]—not long after the oceans formed 4.5 billion years ago, and
-    after the formation of the Earth 4.54 billion years ago.[2][3][6][7]
-    |]
-    "https://en.wikipedia.org/wiki/Earliest_known_life_forms",
-
-    CalendarEntry (3.42 & billionYearsAgo) Nothing
-    "Earliest known life on Earth"
-    ""
-    [text|
-    The earliest known life forms on Earth are putative fossilized
-    microorganisms found in hydrothermal vent precipitates, considered to be
-    about 3.42 billion years old.[1][2] The earliest time for the origin of life
-    on Earth is at least 3.77 billion years ago, possibly as early as 4.28
-    billion years,[2] or even 4.41 billion years[4][5]—not long after the oceans
-    formed 4.5 billion years ago, and after the formation of the Earth 4.54
-    billion years ago.[2][3][6][7] The earliest direct evidence of life on Earth
-    is from microfossils of microorganisms permineralized in
-    3.465-billion-year-old Australian Apex chert rocks.[8][9]
-    |]
-    "https://en.wikipedia.org/wiki/Earliest_known_life_forms",
-
-    CalendarEntry (750 & millionYearsAgo) Nothing
-    "Bones and shells"
-    ""
-    [text|
-    A series of spectacularly preserved, 750-million-year-old fossils represent
-    the microscopic origins of biomineralization, or the ability to convert
-    minerals into hard, physical structures. This process is what makes bones,
-    shells, teeth and hair possible, literally shaping the animal kingdom and
-    even Earth itself.
-
-    The fossils were pried from ancient rock formations in Canada's Yukon by
-    earth scientists Francis Macdonald and Phoebe Cohen of Harvard University.
-    In a June Geology paper, they describe their findings as providing "a unique
-    window into the diversity of early eukaryotes."
-
-    Using molecular clocks and genetic trees to reverse-engineer evolutionary
-    histories, previous research placed the beginning of biomineralization at
-    about 750 million years ago. Around that time, the fossil record gets
-    suggestive, turning up vase-shaped amoebas with something like scales in
-    their cell walls, algae with cell walls possibly made from calcium carbonate
-    and sponge-like creatures with seemingly mineralized bodies.
-    |]
-    "https://www.wired.com/2011/06/first-shells/",
-
-    CalendarEntry (440 & millionYearsAgo) Nothing
-    "Fish with jaws"
-    ""
-    [text|
-    Prehistoric armoured fishes called placoderms were the first fishes to have
-    jaws. They arose some time in the Silurian Period, about 440 million years
-    ago, to become the most abundant and diverse fishes of their day.
-
-    Placoderms dominated the oceans, rivers and lakes for some 80 million years,
-    before their sudden extinction around 359 million years ago. This is possibly
-    due to the depletion of trace elements in our oceans.
-    |]
-    "",
-
-    CalendarEntry (518 & millionYearsAgo) Nothing
-    "Vertebrates"
-    "Animals with backbones"
-    [text|
-    Vertebrates (/ˈvɜːrtəbrɪts, -ˌbreɪts/)[3] comprise all animal taxa within
-    the subphylum Vertebrata (/ˌvɜːrtəˈbreɪtə/)[4] (chordates with backbones),
-    including all mammals, birds, reptiles, amphibians, and fish. Vertebrates
-    represent the overwhelming majority of the phylum Chordata, with currently
-    about 69,963 species described.[5]
-    |]
-    "",
-
-    CalendarEntry (385 & millionYearsAgo) Nothing
-    "Insects"
-    ""
-    [text|
-    Comprising up to 10 million living species, insects today can be found on
-    all seven continents and inhabit every terrestrial niche imaginable. But
-    according to the fossil record, they were scarce before about 325 million
-    years ago, outnumbered by their arthropod cousins the arachnids (spiders,
-    scorpions and mites) and myriapods (centipedes and millipedes).
-
-    The oldest confirmed insect fossil is that of a wingless, silverfish-like
-    creature that lived about 385 million years ago. It’s not until about 60
-    million years later, during a period of the Earth’s history known as the
-    Pennsylvanian, that insect fossils become abundant.
-    |]
-    "https://earth.stanford.edu/news/insects-took-when-they-evolved-wings",
-
-    CalendarEntry (368 & millionYearsAgo) Nothing
-    "Amphibians"
-    ""
-    [text|
-    The earliest well-known amphibian, Ichthyostega, was found in Late Devonian
-    deposits in Greenland, dating back about 363 million years. The earliest
-    amphibian discovered to date is Elginerpeton, found in Late Devonian rocks
-    of Scotland dating to approximately 368 million years ago. The later
-    Paleozoic saw a great diversity of amphibians, ranging from small legless
-    swimming forms (Aistopoda) to bizarre "horned" forms (Nectridea). Other
-    Paleozoic amphibians more or less resembled salamanders outwardly but
-    differed in details of skeletal structure. Exactly how to classify these
-    fossils, and how they might be related to living amphibians, is still
-    debated by paleontologists. Shown at the right is Phlegethontia, an aistopod
-    from the Pennsylvanian.
-
-    The familiar frogs, toads, and salamanders have been present since at least
-    the Jurassic Period. (The fossil frog pictured to the left is much younger,
-    coming from the Eocene, only 45 to 55 million years ago). Fossil caecilians
-    are very rare; until recently the oldest known caecilians were Cenozoic in
-    age (that is, less than 65 million years old), but recent finds have pushed
-    back the ancestry of the legless caecilians to Jurassic ancestors that had
-    short legs. The rarity of fossil caecilians is probably due to their
-    burrowing habitat and reduced skeleton, both of which lessen the chances of
-    preservation.
-    |]
-    "https://ucmp.berkeley.edu/vertebrates/tetrapods/amphibfr.html",
-
-    CalendarEntry (320 & millionYearsAgo) Nothing
-    "Reptiles"
-    ""
-    [text|
-    Reptiles, in the traditional sense of the term, are defined as animals that
-    have scales or scutes, lay land-based hard-shelled eggs, and possess
-    ectothermic metabolisms.
-
-    Though few reptiles today are apex predators, many examples of apex reptiles
-    have existed in the past. Reptiles have an extremely diverse evolutionary
-    history that has led to biological successes, such as dinosaurs, pterosaurs,
-    plesiosaurs, mosasaurs, and ichthyosaurs.
-    |]
-    [text|
-    https://en.wikipedia.org/wiki/Evolution_of_reptiles
-    https://www.thoughtco.com/the-first-reptiles-1093767
-    |],
-
-    CalendarEntry (335 & millionYearsAgo) Nothing
-    "Pangea forms"
-    ""
-    [text|
-    Pangaea or Pangea (/pænˈdʒiː.ə/)[1] was a supercontinent that existed during
-    the late Paleozoic and early Mesozoic eras.[2] It assembled from the earlier
-    continental units of Gondwana, Euramerica and Siberia during the
-    Carboniferous approximately 335 million years ago, and began to break apart
-    about 200 million years ago, at the end of the Triassic and beginning of the
-    Jurassic.[3] In contrast to the present Earth and its distribution of
-    continental mass, Pangaea was centred on the Equator and surrounded by the
-    superocean Panthalassa and the Paleo-Tethys and subsequent Tethys Oceans.
-    Pangaea is the most recent supercontinent to have existed and the first to
-    be reconstructed by geologists.
-    |]
-    "https://en.wikipedia.org/wiki/Pangaea",
-
-    CalendarEntry (243 & millionYearsAgo) Nothing
-    "Dinosaurs"
-    ""
-    [text|
-    For the past twenty years, Eoraptor has represented the beginning of the Age
-    of Dinosaurs. This controversial little creature–found in the roughly
-    231-million-year-old rock of Argentina–has often been cited as the earliest
-    known dinosaur. But Eoraptor has either just been stripped of that title, or
-    soon will be. A newly-described fossil found decades ago in Tanzania extends
-    the dawn of the dinosaurs more than 10 million years further back in time.
-
-    Named Nyasasaurus parringtoni, the roughly 243-million-year-old fossils
-    represent either the oldest known dinosaur or the closest known relative to
-    the earliest dinosaurs. The find was announced by University of Washington
-    paleontologist Sterling Nesbitt and colleagues in Biology Letters, and I
-    wrote a short news item about the discovery for Nature News. The paper
-    presents a significant find that is also a tribute to the work of Alan
-    Charig–who studied and named the animal, but never formally published a
-    description–but it isn’t just that. The recognition of Nyasasaurus right
-    near the base of the dinosaur family tree adds to a growing body of evidence
-    that the ancestors of dinosaurs proliferated in the wake of a catastrophic
-    mass extinction.
-    |]
-    [text|
-    https://www.smithsonianmag.com/science-nature/scientists-discover-oldest-known-dinosaur-152807497/
-    |],
-
-    CalendarEntry (210 & millionYearsAgo) Nothing
-    "Mammals"
-    ""
-    [text|
-    The earliest known mammals were the morganucodontids, tiny shrew-size
-    creatures that lived in the shadows of the dinosaurs 210 million years ago.
-    They were one of several different mammal lineages that emerged around that
-    time. All living mammals today, including us, descend from the one line that
-    survived.
-    |]
-    "https://www.nationalgeographic.com/science/article/rise-mammals",
-
-    CalendarEntry (150 & millionYearsAgo) Nothing
-    "Birds"
-    ""
-    [text|
-    The first birds had sharp teeth, long bony tails and claws on their hands.
-    The clear distinction we see between living birds and other animals did not
-    exist with early birds. The first birds were in fact more like small
-    dinosaurs than they were like any bird today.
-
-    The earliest known (from fossils) bird is the 150-million-year-old
-    Archaeopteryx, but birds had evolved before then. A range of birds with more
-    advanced features appeared soon after Archaeopteryx. One group gave rise to
-    modern birds in the Late Cretaceous.
-    |]
-    "https://australian.museum/learn/dinosaurs/the-first-birds/",
-
-    CalendarEntry (130 & millionYearsAgo) Nothing
-    "Flowers"
-    ""
-    [text|
-    Today, plants with flowers--called angiosperms--dominate the landscape.
-    Around 80 percent of green plants alive today, from oak trees to grass, are
-    flowering plants. In all of these plants, flowers are part of the
-    reproductive system. But 130 million years ago, flowering plants were rare.
-    Most plants reproduced with spores, found today on ferns, or with seeds and
-    cones, found today on pine trees. The plant fossils found in Liaoning,
-    China, show evidence of plants with spores or seeds--and perhaps one of the
-    first flowering plants.
-
-    Researchers have found an ancient plant in Liaoning, Archaefructus, that has
-    very small, simple flowers and could be one of the first flowering plants.
-    Archaefructus lived around 130 million years ago and probably grew in or
-    near the water.
-    |]
-    "https://www.amnh.org/exhibitions/dinosaurs-ancient-fossils/liaoning-diorama/when-flowers-first-bloomed",
-
-    CalendarEntry (85 & millionYearsAgo) Nothing
-    "Tyranosaurids"
-    "The Tyrant Lizards"
-    [text|
-    The name says it all. This group of huge carnivores must have tyrannically
-    ruled the land during the last part of the Cretaceous, 85 to 65 million
-    years ago. Short but deep jaws with banana-sized sharp teeth, long hind
-    limbs, small beady eyes, and tiny forelimbs (arms) typify a tyrannosaur. The
-    Tyrannosauridae included such similar animals (in rough order of increasing
-    size) as Albertosaurus, Gorgosaurus, Daspletosaurus, Tarbosaurus, and of
-    course Tyrannosaurus rex.
-
-    T. rex was one of the largest terrestrial carnivores of all time. It stood
-    approximately 15 feet high and was about 40 feet in length, roughly six tons
-    in weight. In its large mouth were six-inch long, sharp, serrated teeth.
-
-    Just about two dozen good specimens of these animals have been found and
-    these finds are from highly restricted areas in western North America. Henry
-    Fairfield Osborn, of the American Museum of Natural History in New York
-    City, first described Tyrannosaurus rex in 1905. This first specimen of
-    Tyrannosaurus is now on display at the Carnegie Museum of Natural History in
-    Pittsburgh, Pennsylvania.
-    |]
-    "",
-
-    CalendarEntry (445 & millionYearsAgo) Nothing
-    "The first mass extinction"
-    "Fluctuating sea levels cause mass die-off of marine invertebrates"
-    [text|
-    The earliest known mass extinction, the Ordovician Extinction, took place at
-    a time when most of the life on Earth lived in its seas. Its major
-    casualties were marine invertebrates including brachiopods, trilobites,
-    bivalves and corals; many species from each of these groups went extinct
-    during this time. The cause of this extinction? It’s thought that the main
-    catalyst was the movement of the supercontinent Gondwana into Earth’s
-    southern hemisphere, which caused sea levels to rise and fall repeatedly
-    over a period of millions of years, eliminating habitats and species. The
-    onset of a late Ordovician ice age and changes in water chemistry may also
-    have been factors in this extinction.
-    |]
-    "https://www.amnh.org/shelf-life/six-extinctions",
-
-    CalendarEntry (370 & millionYearsAgo) Nothing
-    "Late Devonian Extinction"
-    "The Kellwasser Event and the Hangenberg Event combine to cause an enormous loss in biodiversity"
-    [text|
-    Given that it took place over a huge span of time—estimates range from
-    500,000 to 25 million years—it isn’t possible to point to a single cause for
-    the Devonian extinction, though some suggest that the amazing spread of
-    plant life on land during this time may have changed the environment in ways
-    that made life harder, and eventually impossible, for the species that died
-    out.
-
-    The brunt of this extinction was borne by marine invertebrates. As in the
-    Ordovician Extinction, many species of corals, trilobites, and brachiopods
-    vanished. Corals in particular were so hard hit that they were nearly wiped
-    out, and didn’t recover until the Mesozoic Era, nearly 120 million years
-    later. Not all vertebrate species were spared, however; the early bony
-    fishes known as placoderms met their end in this extinction.
-    |]
-    "https://www.amnh.org/shelf-life/six-extinctions",
-
-    CalendarEntry (252 & millionYearsAgo) Nothing
-    "The Great Dying"
-    "Mass extinction kills more than 95 percent of marine species and 70 percent of land-dwelling vertebrates"
-    [text|
-    So many species were wiped out by this mass extinction it took more than 10
-    million years to recover from the huge blow to global biodiversity. This
-    extinction is thought to be the result of a gradual change in climate,
-    followed by a sudden catastrophe. Causes including volcanic eruptions,
-    asteroid impacts, and a sudden release of greenhouse gasses from the
-    seafloor have been proposed, but the mechanism behind the Great Dying
-    remains a mystery.
-    |]
-    "https://www.amnh.org/shelf-life/six-extinctions",
-
-    CalendarEntry (201 & millionYearsAgo) Nothing
-    "Triassic-Jurassic Extinction"
-    "Death of more than a third of marine species and of most large amphibians"
-    [text|
-    This extinction occurred just a few millennia before the breakup of the
-    supercontinent of Pangaea. While its causes are not definitively
-    understood—researchers have suggested climate change, an asteroid impact, or
-    a spate of enormous volcanic eruptions as possible culprits—its effects are
-    indisputable.
-
-    More than a third of marine species vanished, as did most large amphibians
-    of the time, as well as many species related to crocodiles and dinosaurs.
-    |]
-    "https://www.amnh.org/shelf-life/six-extinctions",
-
-    CalendarEntry (66 & millionYearsAgo) Nothing
-    "Dinosaurs extinct"
-    "Mammals take over land & sea"
-    [text|
-    An asteroid more than 6 miles across strikes the Yucatan Peninsula,
-    triggering the fifth mass extinction in the world’s history.
-
-    Some of the debris thrown into the atmosphere returned to Earth, the
-    friction turning the air into an oven and sparking forest fires as it landed
-    all over the world. The intensity of the heat pulse gave way to a prolonged
-    impact winter, the sky blotted out by soot and ash as temperatures fell.
-
-    More than 75 percent of species known from the end of the Cretaceous period,
-    66 million years ago, didn’t make it to the following Paleogene period. The
-    geologic break between the two is called the K-Pg boundary, and beaked birds
-    were the only dinosaurs to survive the disaster.|]
-    [text|
-    https://www.smithsonianmag.com/science-nature/why-birds-survived-and-dinosaurs-went-extinct-after-asteroid-hit-earth-180975801/,
-    https://www.amnh.org/shelf-life/six-extinctions
-    |],
-
-    CalendarEntry (27.5 & millionYearsAgo) Nothing
-    "Apes and monkeys split"
-    ""
-    [text|
-    Studies of clock-like mutations in primate DNA have indicated that the split
-    between apes and Old World monkeys occurred between 30 million and 25
-    million years ago.
-    |]
-    "https://www.nsf.gov/news/news_summ.jsp?cntn_id=127930",
-
-    CalendarEntry (12.1 & millionYearsAgo) Nothing
-    "Humans and chimpanzees split"
-    ""
-    [text|
-    A 2016 study analyzed transitions at CpG sites in genome sequences, which
-    exhibit a more clocklike behavior than other substitutions, arriving at an
-    estimate for human and chimpanzee divergence time of 12.1 million years.[20]
-    |]
-    [text|
-    https://en.wikipedia.org/wiki/Chimpanzee%E2%80%93human_last_common_ancestor
-    |],
-
-    CalendarEntry (4.4 & millionYearsAgo) Nothing
-    "Humans first walk upright"
-    ""
-    [text|
-    The earliest hominid with the most extensive evidence for bipedalism is the 4.4-million-year-old Ardipithecus ramidus.
-    |]
-    [text|
-    https://www.smithsonianmag.com/science-nature/becoming-human-the-evolution-of-walking-upright-13837658/
-    |],
-
-    CalendarEntry (300 & thousandYearsAgo) Nothing
-    "Modern humans evolve"
-    ""
-    [text|
-    Among the oldest known remains of Homo sapiens are those found at the
-    Omo-Kibish I archaeological site in south-western Ethiopia, dating to about
-    233,000[2] to 196,000 years ago,[3] the Florisbad site in South Africa,
-    dating to about 259,000 years ago, and the Jebel Irhoud site in Morocco,
-    dated about 300,000 years ago.
-    |]
-    [text|
-    https://en.wikipedia.org/wiki/Early_modern_human
-    |],
-
-    CalendarEntry (100 & thousandYearsAgo) Nothing
-    "Human migration out of Africa"
-    ""
-    [text|
-    Between 70,000 and 100,000 years ago, Homo sapiens began migrating from the
-    African continent and populating parts of Europe and Asia. They reached the
-    Australian continent in canoes sometime between 35,000 and 65,000 years ago.
-
-    Map of the world showing the spread of Homo sapiens throughout the Earth
-    over time.
-    |]
-    [text|
-    https://www.khanacademy.org/humanities/world-history/world-history-beginnings/origin-humans-early-societies/a/where-did-humans-come-from
-    |],
-
-    CalendarEntry (4.4 & billionYearsAgo) Nothing
-    "Formation of the moon"
-    "A collision of the planet Theia with Earth creates the moon"
-    [text|
-    Astronomers think the collision between Earth and Theia happened at about
-    4.4 to 4.45 bya; about 0.1 billion years after the Solar System began to
-    form.[15][16] In astronomical terms, the impact would have been of moderate
-    velocity. Theia is thought to have struck Earth at an oblique angle when
-    Earth was nearly fully formed. Computer simulations of this "late-impact"
-    scenario suggest an initial impactor velocity at infinity below 4 kilometres
-    per second (2.5 mi/s), increasing as it fell to over 9.3 km/s (5.8 mi/s) at
-    impact, and an impact angle of about 45°.[17] However, oxygen isotope
-    abundance in lunar rock suggests "vigorous mixing" of Theia and Earth,
-    indicating a steep impact angle.[3][18] Theia's iron core would have sunk
-    into the young Earth's core, and most of Theia's mantle accreted onto
-    Earth's mantle. However, a significant portion of the mantle material from
-    both Theia and Earth would have been ejected into orbit around Earth (if
-    ejected with velocities between orbital velocity and escape velocity) or
-    into individual orbits around the Sun (if ejected at higher velocities).
-    Modelling[19] has hypothesised that material in orbit around Earth may have
-    accreted to form the Moon in three consecutive phases; accreting first from
-    the bodies initially present outside Earth's Roche limit, which acted to
-    confine the inner disk material within the Roche limit. The inner disk
-    slowly and viscously spread back out to Earth's Roche limit, pushing along
-    outer bodies via resonant interactions. After several tens of years, the
-    disk spread beyond the Roche limit, and started producing new objects that
-    continued the growth of the Moon, until the inner disk was depleted in mass
-    after several hundreds of years.
-    |]
-    [text|
-    https://en.wikipedia.org/wiki/Giant-impact_hypothesis#Basic_model
-    https://www.psi.edu/epo/moon/moon.html
-    |],
-
-    CalendarEntry (600 & millionYearsAgo) Nothing
-    "Multicellular life"
-    ""
-    [text|
-    |]
-    ""
-    ]
-
-  where
-    theYear = yearsAgo . toRational . (currentYear -)
-    yearsBeforeCommonEra = yearsAgo . toRational . ((+) (currentYear - 1))
-    earthDescription = [text|
-    The standard model for the formation of the Solar System (including the
-    Earth) is the solar nebula hypothesis.[23] In this model, the Solar System
-    formed from a large, rotating cloud of interstellar dust and gas called the
-    solar nebula. It was composed of hydrogen and helium created shortly after
-    the Big Bang 13.8 Ga (billion years ago) and heavier elements ejected by
-    supernovae. About 4.5 Ga, the nebula began a contraction that may have been
-    triggered by the shock wave from a nearby supernova.[24] A shock wave would
-    have also made the nebula rotate. As the cloud began to accelerate, its
-    angular momentum, gravity, and inertia flattened it into a protoplanetary
-    disk perpendicular to its axis of rotation. Small perturbations due to
-    collisions and the angular momentum of other large debris created the means
-    by which kilometer-sized protoplanets began to form, orbiting the nebular
-    center.[25]
-
-    The center of the nebula, not having much angular momentum, collapsed
-    rapidly, the compression heating it until nuclear fusion of hydrogen into
-    helium began. After more contraction, a T Tauri star ignited and evolved
-    into the Sun. Meanwhile, in the outer part of the nebula gravity caused
-    matter to condense around density perturbations and dust particles, and the
-    rest of the protoplanetary disk began separating into rings. In a process
-    known as runaway accretion, successively larger fragments of dust and debris
-    clumped together to form planets.[25] Earth formed in this manner about 4.54
-    billion years ago (with an uncertainty of 1%)[26][27][4] and was largely
-    completed within 10–20 million years.[28] The solar wind of the newly formed
-    T Tauri star cleared out most of the material in the disk that had not
-    already condensed into larger bodies. The same process is expected to
-    produce accretion disks around virtually all newly forming stars in the
-    universe, some of which yield planets.[29]
-    |]
-    recombinationDescription = [text|
-    At about 370,000 years,[3][4][5][6] neutral hydrogen atoms finish forming
-    ("recombination"), and as a result the universe also became transparent for
-    the first time. The newly formed atoms—mainly hydrogen and helium with
-    traces of lithium—quickly reach their lowest energy state (ground state) by
-    releasing photons ("photon decoupling"), and these photons can still be
-    detected today as the cosmic microwave background (CMB). This is the oldest
-    direct observation we currently have of the universe.
-    |]
-    recombinationReferences = [text|
-    https://en.wikipedia.org/wiki/Chronology_of_the_universe#The_very_early_universe
-
-    3. Tanabashi, M. 2018, p. 358, chpt. 21.4.1: "Big-Bang Cosmology" (Revised
-    September 2017) by Keith A. Olive and John A. Peacock.
-
-    4. Notes: Edward L. Wright's Javascript Cosmology Calculator (last modified
-    23 July 2018). With a default H 0 {\displaystyle H_{0}} H_{0} = 69.6 (based
-    on WMAP9+SPT+ACT+6dFGS+BOSS/DR11+H0/Riess) parameters, the calculated age of
-    the universe with a redshift of z = 1100 is in agreement with Olive and
-    Peacock (about 370,000 years).
-
-    5. Hinshaw, Weiland & Hill 2009. See PDF: page 45, Table 7, Age at
-    decoupling, last column. Based on WMAP+BAO+SN parameters, the age of
-    decoupling occurred 376971+3162−3167 years after the Big Bang.
-
-    6. Ryden 2006, pp. 194–195. "Without going into the details of the
-    non-equilibrium physics, let's content ourselves by saying, in round
-    numbers, zdec ≈ 1100, corresponding to a temperature Tdec ≈ 3000 K, when the
-    age of the universe was tdec ≈ 350,000 yr in the Benchmark Model. (...) The
-    relevant times of various events around the time of recombination are shown
-    in Table 9.1. (...) Note that all these times are approximate, and are
-    dependent on the cosmological model you choose. (I have chosen the Benchmark
-    Model in calculating these numbers.)"
-
-    https://en.wikipedia.org/wiki/Recombination_(cosmology)#cite_note-2
-    |]