"In the beginning" "There was darkness," "And then, bang..." "Giving birth" "To an endless" "Expanding existence" "Of time, space and matter." "Every day," "New discoveries are unlocking" "The mysterious," "The mind-blowing," "The deadly secrets of a place" "We call the universe." "What would happen if our moon" "Suddenly disappeared?" "Global tsunamis" "Decimate coastlines" "Around the world" "As ocean waters surge" "Toward the gravitational pull" "Of the sun." "Sea currents shift," "Changing weather patterns" "And destroying food supplies." "Eventually earth's axis" "Tilts wildly," "Turning the poles" "Into tropical jungles" "And the equator" "Into frigid wastelands." "New species emerge," "While others go extinct." "Our planet" "Becomes unrecognizable" "The day the moon was gone." "The Universe - 4x02 August 25, 2009" "The moon" "Is a barren lifeless rock," "But it plays" "A surprisingly important role" "In the story of life on earth." "How important?" "Let's remove it from the sky" "And find out." "Strange things start to happen" "Almost immediately." "People on the coast" "Are the first" "To notice the change." "This would probably create" "Something like a Tsunami," "A tidal wave, which would be" "Very dramatic indeed." "It's well known that the moon" "Controls earth's tides." "As it orbits around us," "Its mass tugs our oceans" "Toward it," "Causing a tidal bulge" "On the side of the planet" "Nearest the moon." "And through a strange quirk" "Of gravitational physics," "It forms a second bulge" "On the side," "Farthest away from the moon." "Few people realize" "The sun also plays a role" "In governing the tides," "But because it's 400 times" "Farther from us than the moon," "Its gravitational influence" "On the oceans" "Is relatively small," "About 1/3 of the total effect." "But with the moon" "Out of the picture," "The sun is now in control." "Well, with the moon up here," "Its gravitational pull" "Is sort of pulling" "A dome of water up." "There's a big sort of bulge." "Then imagine" "You just snipped the cord" "And the water" "Had to flow back out." "The water rushes" "Toward the gravity of the sun" "In a massive global Tsunami." "The force of the waves" "Depends on where the moon is" "In relation to the sun" "When it disappears." "If the moon vanished" "At full moon or at new moon," "That's when the moon is lined up" "With the earth and the sun." "The lunar tidal bulges" "Would shrink" "To solar tidal bulges" "In the same spots," "And the extra water" "From the lunar bulges" "Would quickly flow" "To other parts of the globe." "But there's an even more" "Dramatic possibility." "If the moon vanished" "When it's at quarter moon," "Either first quarter" "Or last quarter," "Then the moon's tidal bulge" "Is not in the same place" "As the sun's tidal bulge." "And so I expect you would see" "A very quick motion" "Of earth's oceans" "From the lunar tidal bulge" "To the solar tidal bulge." "Some experts believe" "This more drastic" "Lateral shift in ocean water" "Would blast coastal spots" "Around the world." "The powerful pulses" "Would be similar to the 2004" "Southeast Asian Tsunami," "Except the waves would cause" "Even more death and destruction" "Since they'd be worldwide." "Two massive east-to-west" "And west-to-east waves" "Would be initiated" "On opposite ends of the earth." "A seaside city like Miami" "Would be pummeled" "By a 50-foot wall of water" "That would destroy" "Most coastal buildings" "And sweep across" "The entire width" "Of Southern Florida," "Putting nine million lives" "At risk." "But with such" "A Titanic shift of water," "Could there be" "Other unpredictable results?" "One can imagine" "That perhaps the east-west" "Or north-south motion" "Of that water" "Could disrupt the currents." "The Gulf stream" "Carries warm water" "From the Caribbean" "Up to Great Britain" "And it helps keep Great Britain" "A lot warmer" "Than it otherwise would be" "Considering how far north it is." "Climate is" "A very delicate system" "And you tweak one part of it" "And another part responds." "And then one can imagine" "That food productivity" "And the overall way of life" "Would be dramatically altered" "If it were cooler" "In northern Europe." "The Sahara desert" "Is a great example of someplace" "That used to be green and lush" "And now is completely a desert." "Having changes with climate" "Can really have impact" "On our survival." "But the biggest impact" "On our planet" "Would be the changes" "To earth's steady tilt," "A unique feature" "That gives us" "Our four regular seasons." "The thing" "That locks our planet's tilt" "To about 23.5 degrees" "So consistently" "Is the presence of the moon" "That acts as a large stabilizer." "If we don't have" "The moon anymore," "We may get into a regime" "That's much more like mars," "And mars, instead of being" "At a stable 23.5 degrees," "Goes through wild variations" "Of the tilt," "Varying from" "Maybe as low as 15 degrees" "On the low side," "All the way up to something like" "About 75, 80 degrees" "On the high side." "Without the moon," "Our axis begins" "Fluctuating erratically" "Over several" "Hundred thousand years." "The gravitational pull" "From other planets" "In the solar system" "Starts wreaking havoc on earth." "Our stable seasons" "Shift dramatically" "As different parts of our planet" "Tilt radically toward the sun" "During some periods" "And away at others." "Soon as you" "Get rid of the moon," "You're stuck with this" "Radical tilting of the axis" "Back and forth and therefore" "Radical climate changes" "That don't happen today." "Earth becomes" "A very strange world" "As mankind struggles" "To adapt and survive." "If we go to a situation" "Where we don't have" "That stabilization," "Those very small changes" "Become very, very big." "We may go to a situation" "Where the ice becomes stable" "Over the tropics." "Imagine jungles and forests" "In Antarctica" "And ice sheets and glaciers" "In central Africa." "The tilt would vary" "On time scales" "Of a few hundred thousand years," "These are time scales" "Of ice ages coming on the earth." "We know how much" "Of an impact that had." "Humanity had a hard time" "Adjusting to those changes" "As we came out" "Of the last ice age." "It's very difficult" "To predict exactly" "What would happen to humans," "Because we're not sure" "How rapidly we're able to adapt" "To radically changing" "Environments." "And if our moon" "Disappeared permanently," "Life in the sea" "And on the shore would be" "Drastically transformed." "Sharks would lose" "Their hunting prowess," "Unable to track" "The schools of fish" "Swarming above them" "In the moonlight." "Crabs, used to mating" "At extreme low tides" "Become disoriented" "At the loss of lunar phases." "Grunion that lay their eggs" "During a high tide and full moon" "Suffer reproductive disruption." "Even primitive" "Aquatic plant life" "Would be affected." "Many species" "Will spend their evenings" "On the surface," "Interacting with moonlight." "The moon comes up," "The algae are moving up" "And they're followed" "By all of the organisms" "That eat the algae" "And the organisms that eat them," "So the whole ecology" "Of the ocean is tuned to light." "All of these organisms" "Will be completely disrupted." "None of their ecology will work" "Because they won't have" "The usual sensing signals." "Millions of people" "Would suffer from food shortages" "And coastal economies" "Would be devastated" "By the worldwide crash" "In marine life populations." "I would liken it to one of us" "Suddenly waking up one morning" "And discovering" "We were blind or deaf." "That would be a chaotic thing." "An earth without the moon" "Is a rudderless planet," "Highlighting just how critical" "This big rock is" "To sustaining life here." "There are over 150 moons" "In our solar system," "But earth's moon" "Is truly unique." "Our moon is unlike" "Any of the other moons" "In the solar system." "It is huge compared to earth." "It's about" "A quarter of the size of earth," "And you don't see that" "In any of the other planets." "Because the moon is so big" "Relative to the earth," "It's as if we are really" "In a double-planet system." "There's a crude way to think" "About the effect of the moon" "Stabilizing this axial tilt" "Of the earth." "If you've noticed," "Tightrope walkers" "Will carry this long pole" "And that gives more stability" "Because there's mass out there" "On the end of the pole" "And it's harder" "To fall off the line." "So it's that same kind of thing" "That the mass at a distance" "Can affect the stability" "Of the system." "But the moon" "Has not always been by our side." "There was a time" "Early in earth's history" "When there was no moon," "A period when our planet" "Was a strange place" "With eight-hour days" "And a molten landscape" "Too harsh for life," "And then suffered" "The most violent collision" "In its history." "It's hard to imagine" "That there was a time" "When our earth" "Did not have a moon." "Our planet was formed 4.5 billion years ago" "By accumulating and fusing" "Large amounts of debris" "In the early stages" "Of our volatile solar system." "During that early period," "Our moonless earth" "Was a monstrous stew" "Of flowing lava," "Molten rock and liquid iron." "Its atmosphere was filled" "With carbon dioxide belched" "From the bowels of the earth," "Thick, heavy" "And uninhabitable for life." "There was almost nothing" "On the planet." "This was a nasty place to be." "Lots of things were condensing." "It was an extremely" "Hostile place," "Even to rock chemistry." "So the rocks were melted." "Everything was a mess." "Our original earth," "Without its moon," "Was an unrecognizable world." "The early earth" "Was a really hot place." "In fact, that era of the earth" "Is called the hadean," "Like hades, because, well," "Because it was really hot." "There was a tremendous amount" "Of volcanism" "And a lot of impacts coming in." "There was probably" "A lot of lightning" "And out-gassing," "Both from the volcanoes" "And from steam." "The stability" "Of our early solar system" "Was not much better." "It was created" "Out of a huge disc" "Of gas debris and dust" "That swirled" "Around the newly formed sun." "Our early solar system was" "Kind of like a roller derby." "Everybody was generally" "Going in the same direction," "But there was a lot of chaos." "There was a lot of clumping" "And accrediting" "And things getting flung" "To the inside and crossing lanes" "To the outside." "People all spilling over" "Each other," "Mashing up in the corner." "It was a real mess." "Without the moon," "We can only guess" "At the earth's early tilt" "And rotation rate." "That would have been determined" "By the multiple" "Glancing collisions" "From the innumerable asteroids" "And protoplanets" "That ricocheted throughout" "Our early solar system." "If you kind of average" "Over the solar system," "Look at all the planets" "And the big asteroids" "And make a bell curve" "Of rotation speeds," "It looks like" "The typical rotation speed" "Might be eight hours," "Something like that." "So we could make a guess" "That that might have been" "The likely rotation speed" "Before the moon was formed." "Then, about 10 million years" "After our moonless earth" "Began taking shape," "There was a massive collision." "Now widely accepted" "By astronomers," "The giant impact theory" "Says that a mars-sized planet" "Collided at an oblique angle," "At 25,000 miles per hour" "With earth." "The impactor" "Blasted more than 70%" "Of the earth's molten crust" "Into space." "A giant whirling arm" "Made up of 5 billion cubic miles" "Of blazing rock and light metals" "Was launched into orbit" "Around our planet." "The gravity of the larger chunks" "Began pulling smaller particles" "Towards them." "Within one year," "It coalesced into our moon." "The only materials" "That were blown out" "From the earth" "Were the crustal rocky material." "And that's what" "The moon's made out of." "In fact, if you go" "To any other place" "In the solar system," "For example, mars," "Or you look at meteorites" "That come" "From the asteroid belt," "There are certain ratios" "Of the different types" "Of oxygen." "That ratio in other parts" "Of the solar system" "Is very different" "Than what we see in the earth." "Now we fly to the moon," "We get the moon rocks," "We bring them back." "They have exactly" "The same oxygen-isotope ratio" "As the earth." "So that material" "Came out of the earth," "And that fits this idea" "Of an impact theory." "The energy released" "In the giant collision" "Equaled a force" "Of six trillion atomic bombs." "That's a thousand atom bombs" "For every person" "In earth's current population" "Of six billion people." "The impactor planet" "That hit earth" "Was thought to have formed" "In an area of our solar system" "Called the Lagrangian points." "These are regions 60 degrees either ahead of" "Or behind the earth," "But at a similar distance" "From the sun." "Debris can stay fixed" "In the Lagrangian points" "For tens of millions of years," "Locked between" "The gravitational influence" "Of the sun and earth." "But eventually something" "Knocked the impactor" "Off its fixed course." "That something was Jupiter." "Every time Jupiter" "Passed by us in its orbit," "It would be giving a little tug" "To this impactor planet." "And each little tug" "Wouldn't be very big." "But if you think about," "For example, having a car" "That's stuck in a ditch" "Or stuck in a snow bank," "How do you get that car" "Out of the snow bank?" "Well, the way you do it" "Is you rock the car." "You push it a little bit," "It comes back," "Push a little bit more," "It comes back a little farther." "And this way" "With a bunch of little pushes," "You eventually free it," "And that's exactly" "What Jupiter did" "To this impactor planet." "And once it gets away" "From the Lagrange point," "It's no longer stable" "And it's doomed." "It's eventually" "Going to collide with earth." "After the giant cataclysm," "The inner part" "Of the whirling arm" "Of ejected debris forms a clump" "That consists of materials" "From the impactor's iron core." "That heavier clump" "Recollides with earth" "And is absorbed" "Into our planet's center." "The giant impact" "Was really the biggest thing" "That ever happened to earth." "What we have now" "Is a core and a half." "That makes our planet denser" "And our gravity stronger" "Than it would be otherwise." "The larger molten core" "Takes longer to cool" "Than the earth's original core" "Would have." "Heat is constantly pushed" "Up and through" "The thin crust of the earth," "Creating fissures." "It's possible" "That this larger core" "Helped create the sustained" "Plate tectonic system" "That formed our continents," "A unique planetary feature" "In our solar system." "As an example," "Mars was much smaller." "It cooled much quicker" "And so it has no crustal plates." "Most critically," "The collision knocks the earth" "Onto its current axial tilt" "Of 23.5 degrees" "And speeds up its rotation" "From eight hours" "To just five hours." "Within a year, the moon forms" "Roughly 14,000 miles away" "From earth," "Significantly closer" "Than its current distance" "Of 234,000 miles." "You've got" "This immense moon in the sky, 15 times as big" "As the present moon." "So think about this thing" "Rising and rising and rising" "Until it fills up" "A pretty big chunk" "Of that evening sky," "And imagine it being red" "Because it's full" "Of this molten lava" "Around the surface." "And imagine that looming" "Over your head." "It's mind boggling." "The early moon's" "Gravitational pull on earth" "Is roughly 200 times stronger" "Than today" "Because of its much closer" "Distance." "Though no oceans exist yet," "The lunar tidal forces" "Are 3,400 times more powerful." "They lift and drop" "Large crusts of molten rock" "To more than half a mile high," "Twice a day." "Our early planet's axial tilt" "Stabilizes," "Due to the moon's formation" "And its mass acts as an anchor." "But the earth's spin" "Begins slowing" "Because the moon's gravitation" "Creates a tidal bulge" "Around our planet's mid-section," "Causing a drag" "On the earth's rotation." "Let the earth be" "This green balloon" "And here is the moon." "If the earth weren't rotating," "The tidal bulge would point" "Directly toward the moon." "But the earth is rotating" "Pretty quickly," "So in fact the tidal bulge" "Tends to be a little bit ahead" "Of the direction" "Toward the moon." "That means the moon's gravity" "Is pulling back" "On the earth's bulge" "A little bit," "Retarding its rotation" "Ever so slightly." "But the tidal bulge on earth" "Also has a reactive force" "On the moon." "This tidal bulge" "Pulls the moon ahead" "In its orbit." "It's constantly trying" "To tug the moon faster," "But the moon doesn't want" "To go faster in its orbit." "Instead what happens," "If you imagine" "Throwing a slingshot" "And swinging it faster." "It wants to go out" "And that's what the moon does." "It goes outward" "Because it's being tugged faster" "In its orbit." "So gradually over the years," "The moon is moving" "Farther and farther out." "The complex" "Gravitational dance" "Between the two partners" "Is now pushing the moon away" "From earth at a rate" "Of 1.5 inches per year." "Over billions of years," "The moon's recession" "Has slowed the earth's rotation" "From five-hour days" "To our 24-hour day today." "The whole idea" "Of this rotation of the earth" "Being influenced by the moon" "Is a little bit like" "What you see" "When a figure skater is spinning" "And when she" "Pulls her arms in close" "And spins, she spins faster," "And then throws her arms out" "To slow down." "And this is all" "What the physicist would call" "Angle of momentum." "But it's the same idea" "As the moon moved out," "It's kinda like" "Throwing those arms out" "And that slows down the rotation" "In the whole system." "But what if the giant impact" "Had never happened." "The changes to earth" "Would be even more drastic" "Than if the moon" "Now suddenly disappeared." "Today, would we recognize an Earth that never had a Moon?" "And would humans even exist?" "If the moon" "Disappeared instantly," "Earth would undergo changes" "Like possible tsunamis," "A shift in ocean currents," "Sea life extinctions," "And eventual" "Massive climate swings." "But if the moon" "Had never existed," "Earth would be unrecognizable" "To anyone today." "Without the moon," "Life on earth" "Would probably look" "Quite different." "In particular, humans might well" "Never have come into existence." "About 150 million years" "After a moonless earth forms 4.5 billion years ago," "It moves out" "Of its hot molten phase" "And begins cooling." "The day is only" "About eight hours long." "If we had an eight-hour" "Rotation period, we'd have" "Four hours of daylight," "Four hours of night." "The nights would be" "Totally black" "If we don't have a moon." "Once cooled," "Our planet is temperate enough" "To retain water." "Heat escaping from earth's core" "Drives steam and carbon dioxide" "Beyond the surface," "Creating a thick atmosphere." "Over a period of time," "Many, many, many, many years," "All that atmosphere would have" "Kind of collapsed back out" "And then as it cooled" "The oceans would have formed" "In torrential rainstorms." "Icy asteroids" "Continually pummel the planet," "Bringing in another" "Large source of water." "With a smaller," "Cooler molten core," "There are probably" "No plate tectonics," "And therefore," "No large mountains" "And huge ocean basins." "Water soon covers" "Most of the planet's" "More uniform crust." "We certainly would have" "A higher sea level" "Than we have today," "Less continental area," "And that would be" "A different world." "Our blue marble" "Would be even bluer." "Ironically," "Even with all that water," "The early moonless earth" "Would have smaller tides." "Determined only" "By the gravitation of the sun," "They would be just 1/3 the size" "Of our current tides." "The range between" "High and low tide" "Would remain constant" "Throughout the year" "And would occur at exactly" "The same time each day." "That means" "The intertidal regions" "Would have been narrower." "Probably leading" "To less diversification of life" "And perhaps even impeding" "The progress of life" "From the oceans to the land," "Because it's" "In the intertidal regions" "Where creatures have to develop" "The ability to survive" "Both in the water and on land." "With an eight-hour day," "Just four hours of light" "Followed by four hours" "Of moonless black," "The early earth spins" "Three times faster than today." "The winds howl," "Due to the aerodynamics" "Of earth's quicker rotation." "Jupiter, for example," "Is a giant planet" "That spins very rapidly." "It has a 10-hour spin period" "And it's got ferocious winds" "In its upper atmosphere," "Hundreds of miles an hour," "And incredible storms" "Like the great red spot," "Which has been" "Around for centuries." "Now earth probably" "Would be spinning more rapidly" "Than it is now," "And that would generally lead" "To stronger winds" "And more violent hurricanes" "And other storms." "Early earth's fast spin" "Results in another" "Important side effect." "The rotation of earth's core," "Particularly the molten part" "Of the core, is believed to be" "What generates" "Our magnetic field." "And so if the earth rotates" "Three times faster," "The magnetic field" "Is three times stronger." "The enhanced magnetic field" "Over the moonless earth" "More effectively deflects" "High-energy" "Solar flare particles" "Towards the earth's poles," "Resulting in larger," "More spectacular auroras." "But by blocking" "The solar flares," "Not as much radiation" "Zaps life" "In the lower atmosphere," "Decreasing mutations" "That drive evolution." "A stronger magnetic field" "Might have slowed the rate" "At which life evolved on earth." "Without the moon," "The developing earth suffers" "Intense climate volatility." "Over many periods, each lasting" "Several million years," "The earth's axis" "Is pulled and pushed" "By the sun and other planets." "Without the stabilizing" "Influence of the moon," "Conditions would have paralleled" "What happened to mars." "What we've learned" "In the last 15 or 20 years" "Is that mars" "Has a very unstable axis" "Because it has no big moon," "And when we look at mars" "And we can actually see" "On the surface of mars" "Geological features that formed" "Under very different" "Climate regimes" "When the polar axis" "Was tilted over." "On mars," "We actually see these features" "Like the dry river channels" "And glacial deposits" "And other features..." "Ice close to the equator..." "And so the big realization" "Was oh, yeah, the climate" "Has been changing on mars" "And this explains" "That we're seeing" "Older features." "Like the red planet," "A moonless earth's axis" "Would tilt wildly," "Turning our planet Topsy-turvy." "Our axis over a period" "Of millions of years" "Would wobble chaotically." "It would sometimes be vertical." "It would sometimes be" "Close to horizontal." "When it's vertical," "Then the whole earth might be" "Kind of a tropical paradise." "When it's horizontal," "You could actually" "Have the poles" "Pointing towards the sun" "And the poles" "Actually getting jungles." "So you'd see very big changes" "In earth's climate as a result" "Of this chaotic wandering" "Of earth's axis." "And this would make it" "More difficult" "For life to flourish" "Because it would constantly" "Have to adapt" "To different conditions," "To ice ages" "And to extremely hot ages." "So what would life look like today if we never had a moon?" "Short days, high winds and other changes could produce a freakish world with creatures that look like straight out of science fiction." "Billions of years ago" "When a planet-sized asteroid" "Crashed into earth." "But what if" "That violent collision" "Never happened?" "If the moon never came along" "To stabilize our planet," "Earth would be an alien place." "The spin of early earth" "Was very fast..." "With about four hours" "Of daylight," "Followed by four hours" "Of darkness." "Over billions of years," "The sun's gravity" "And tidal friction" "Would lengthen that 8-hour day" "To 12 hours." "But this is still twice as fast" "As the current earth spins," "Which makes" "For some extreme weather," "Including devastating storms" "And high winds." "If the moon hadn't formed," "You'd certainly get" "A wildly different environment" "On the earth." "With a faster-turning earth," "You get more jet streams," "You get more turbulence" "Probably, maybe bigger storms," "More lightning" "Because of the friction" "Of the different masses of air" "Moving." "In some places," "The winds could reach 100 or 200 miles an hour." "There would also be" "Stronger hurricanes" "And earth would have" "Larger waves" "Battering the coastlines." "And without" "The moon's stabilizing effect," "The rapidly spinning earth" "Tilts back and forth." "Over hundreds of thousands" "Of years," "Our planet suffers the ravages" "Of ever-shifting climate" "Because of the erratic changes" "In axial tilt..." "As different regions" "Are blasted by heat," "Then covered by ice," "Again and again." "And without the moon," "There is another layer" "Of axial instability." "Even though today's earth" "Is stabilized by the moon," "There is still a wobble" "To the earth's rotation," "Known as precession." "Earth's tilt is 23.5 degrees," "But over a period" "Of 26,000 years," "It goes through" "Conical variations like this." "And if the moon" "Had never formed," "This wobbling would be" "Much more unpredictable." "If we didn't have the moon," "The earth would precess" "Much more slowly" "And this is one cause" "For chaotic variations" "In the axial tilt." "A slower precession of the earth" "Would lead to" "A much more unstable" "Axis of rotation for the earth." "Without the moon," "Earth's axis today" "Would be like" "The slower spinning top," "Precessing, gyrating" "And wobbling" "In ever larger conical circles." "Right now, 26,000 years," "A very stable zone" "You get it going slower," "So it's maybe 40,000," "Maybe 50,000, maybe 60,000," "Then you hit the chaotic range," "And then everything goes wrong." "With the more forbidding" "And shifting climate," "Evolution on a moonless earth" "Varies between" "Bursts of adaptation" "And violent extinction." "Bizarre life forms mushroom." "Plant species are vulnerable" "As they don't have" "The mobility to stay ahead" "Of speedy climate change." "And complex life forms" "Like humans" "Probably wouldn't" "Stand a chance at all." "The variations in climate" "Would be extreme" "And rather rapid" "And it would probably" "Make it difficult" "For complex creatures to evolve" "Because most complex creatures" "Can't evolve very quickly" "To changes in their environment." "Instead, primitive organisms" "Would predominate and endure." "Bacterial life is able" "Not only to adapt more quickly," "But also to withstand" "More extreme environments." "We see bacteria" "Under the deep ice cores" "Of the antarctic or Greenland," "And we see bacteria" "That live in steaming," "Boiling pots in Yellowstone." "If complex life" "Were to evolve," "It would look very different," "Due to short days, high winds," "And other features" "Of a moonless earth." "It would be much more hostile" "Than it is now." "You would see" "That all of these winds" "And all of the noise" "And all of the clouds," "Moving from water" "To life on land" "Would be very tough." "We might see" "Shorter life spans" "Because things" "Are going on faster." "During the day," "There will be a limited time" "To metabolize and gain energy" "And do things." "Organisms would have to be" "A little more clever." "Evolution would favor" "Short, stout creatures" "And plant life that could" "Withstand ferocious hurricanes." "Jungles wouldn't exist" "Since they need wind barriers" "To flourish." "And there probably" "Wouldn't be any creatures" "Swinging from branch to branch," "Due to stubbier plant life" "And high winds." "I would expect that creatures" "Generally wouldn't be as tall" "Because they'd have" "A harder time" "Holding themselves up." "And trees" "With shallow root systems" "Wouldn't become very tall." "Palm trees, for example," "Probably wouldn't survive" "Too well." "The constant gusts" "Would push other adaptations." "Sailing, you know," "Maybe membranes" "That let you take off" "And leap through the air." "And the perpetual" "Gale-like conditions" "Would create" "An exceptionally loud planet." "If animals made noises" "To communicate," "They'd have to be very different" "From the constant" "Shrieking wind sounds." "The use of sound" "At wavelengths" "That are not the sound" "Of the background noise." "If you have a receptor" "That just zeros out that noise," "We might be able" "To speak like this," "And be heard perfectly." "We might all be sopranos" "And have ears" "Tuned to a different pitch." "Or more visual cues" "Might be developed" "To cut through" "The audio overload." "Creatures might develop" "Extra limbs" "To not only shield themselves" "From the wind," "But also use their appendages" "To communicate," "Like sailors" "Using semaphore signals." "Perhaps speech" "Would not develop," "So maybe" "Other forms of communication," "Whether the color changes," "Expression changes," "Hand languages, who knows." "Even today," "Many of earth's beings," "Such as fireflies," "Squids, krill and jellyfish," "Communicate by changing" "Their body colors." "Because of the dark nights," "Creatures might also develop" "Enhanced vision" "And sensory systems similar" "To the night-vision goggles" "And infrared displays" "Used by the military." "The interesting possibility" "Is that life might be able" "To develop sensors" "That were so good" "That they could" "Actually sense starlight," "And this would be" "Something colossal." "It looks and sounds like" "A rough and too tough world," "Unfit for human habitation." "Luckily, when the moon formed," "It created the conditions" "For people to develop" "And prosper." "But our moon is also moving" "Farther away from earth" "Every year." "Does that mean" "There will be another time" "In earth's future" "Without the moon?" "4.5 billion years ago," "The young earth" "Was a hellish molten place," "Unfit for life." "So then," "How did a violent collision" "By an object the size of mars" "Soon after the earth's formation" "Create the conditions" "For the complex life" "We're part of today?" "The body blow to earth" "Knocked our planet" "To its current tilt" "And the formation of the moon" "Kept it there." "The mass of the moon" "Out there," "What it's done is it's prevented" "The tugs of the other planets" "From causing the earth's tilt" "To change too much." "So it provided" "A real stabilizing effect" "On our climate because of that." "The collision also created" "A chain reaction of forces" "That set the stage for life." "When the iron cores" "Of the two planets combined," "It created a larger core" "For the new earth." "The collision also knocked off" "Much of the earth's crust." "This combination" "With large amounts of heat" "Pushing up from a giant core" "Through a thin crust" "Likely created the conditions" "For sustained plate tectonics." "The movement of these plates" "Formed mountain ranges" "And deep basins," "And the resulting" "Volcanic activity" "Spewed out the gases" "That created our atmosphere." "Water eventually settled" "In the basins, creating oceans," "Leaving continents" "Of land above." "But life" "Still had a tough time" "Getting started" "In the early days of earth." "For the first" "Half billion years" "Of the earth's" "And the moon's existence," "They were bombarded by debris" "That was still finishing up" "The formation" "Of the solar system." "So even if primitive life," "Microbes and bacteria," "Had formed in the first" "Few hundred million years," "They might easily" "Have been wiped out" "By these giant things" "Crashing into earth." "Now, we have evidence for life" "Dating back" "To 3.8 billion years ago." "That's shortly after the end" "Of the era of heavy bombardment." "By then," "Due to tidal friction" "Between the earth and moon," "The moon had moved" "Slightly farther away" "From earth," "And earth's rotation" "Had slowed to roughly" "A 10-hour day." "But since the moon" "Was still much closer" "Than today," "The tides in earth's" "Early oceans were humongous." "The tides went way inland" "And poured back out to sea." "Twice a day," "You'd get big Gulf of water in" "And when it drained back out," "It carried a lot of minerals" "And solland other rts" "Of the earth's crust" "Back out to sea with it." "So there was" "This constant erosion" "And scrubbing of the land," "Certainly a unique environment" "That might have been" "Just right for life to develop." "The area" "Between high and low tide," "Known as the intertidal region," "Was enormous." "High tides would rush" "Hundreds of miles inland," "Then back out a few hours later." "During the low tides," "Molecular strands began forming" "In some of the endless miles" "Of tide pools." "What happens" "When water evaporates?" "The h2o molecules go away" "And everything else is left." "So the organic sludge" "In the pool" "Gets more and more concentrated" "As the water evaporates," "So this was the idea" "That life formed" "In these little pools." "Around 570 million years ago," "Almost 3.9 billion years" "After the giant impact," "Earth's ocean life" "Begins moving onto land," "Giving birth to complex species." "The bigger" "The intertidal regions," "The greater" "The resulting diversity of life" "Because you can have species" "That live in these environments" "That are sometimes" "Exposed to the sun" "And sometimes underwater." "Over billions of years," "Our earth seems to have reached" "A perfect equilibrium" "That has allowed" "For the evolution of a diverse," "Intricate and fragile ecosystem." "There are some climates" "That are too uniform," "No seasonal changes and so on," "And don't need the life" "Because there's" "No environmental stress." "And on the other hand," "Climates that are too variable" "Where the seasons are changing" "All the time," "You're getting hit" "By an asteroid" "Every million years." "Planets like that" "Would probably try to form life," "But they couldn't get it going" "Because things" "Would change too fast." "So maybe there was a situation" "That's just right in the middle" "And maybe the earth-moon system" "Is somewhere in that range," "Which has fostered," "Not only formation" "Of primitive life," "But the evolution of that life" "Into folks like us." "But though" "Our moon stabilizes things," "It continues to recede from us" "At a rate of 1.5 inches per year" "While it slows our spin." "Scientists estimate" "That we're adding 2 seconds to our day" "Every 100,000 years." "A billion years from now," "Our days might last 26 hours" "Rather than 24 hours," "Which is great if you're" "A procrastinator like me," "You could always use more time." "So what will happen" "To the unique" "Earth-moon partnership" "That made life on earth" "Possible?" "Will the moon eventually" "Just drift away" "Out of earth's" "Gravitational influence?" "The rate will be so slow" "That it won't be" "A very big effect" "And long periods of time" "Will pass without much change," "So long that we will" "Have had time for our sun" "To run out of fuel" "And become a red giant." "At that time," "The earth will be destroyed," "And so will the moon" "At the same time." "We'll all get baked together." "So maybe it's comforting" "To know" "That five billion years from now" "On the day the earth" "Faces its end," "We won't be alone." "Our anchor in the sky" "Will be there," "The glowing orb" "That made advanced life on earth" "Possible."