>>> THE MOON MAY HAVE PLAYED AN IMPORTANT ROLE IN THE DEVELOPMENT OF LIFE ON EARTH?

HOW?

THAT'S SOMETHING SCIENTISTS ARE STUDYING.

DO YOU HAVE A QUESTION ABOUT THE MOON?

SCIENTISTS ARE STANDING BY WITH ANSWERS.

STAY TUNED.

"D4K" IS NEXT.

>>> I'M JOAN CARTAN-HANSEN.

WELCOME TO "D4K."

TODAY WE'RE LEARNING ABOUT THE MOON.

BEFORE WE GO TO THE STUDIO TO ANSWER YOUR QUESTION, LET'S LEARN MORE.

THE MOON IS THE EARTH'S ONLY NATURAL SATELLITE.

A SATELLITE IS AN OBJECT THAT TRAVELS AROUND ANOTHER OBJECT.

IT TAKES THE MOON ABOUT 27 DAYS AND EIGHT HOURS TO GO AROUND THE EARTH.

THE MOON IS ABOUT 238,000 MILES AWAY.

THAT SOUNDS LIKE A LOT, BUT IN TERMS OF SPACE, THAT'S PRETTY CLOSE.

OUR NEXT NEAREST NEIGHBOR IS THE PLANET VENUS, AND THAT'S 25 MILLION MILES AWAY.

THE MOON IS MADE OF ROCK.

FROM EARTH WE CAN ONLY SEE ONE SIDE OF THE MOON AND IT'S ALWAYS THE SAME SIDE.

ITS SURFACE HAS THOUSANDS OF CRATERS.

CRATERS ARE RING-SHAPED FLAT LANDS WITH WALLS AROUND THEM.

A CRATER FORMS WHEN A METEORITE HITS THE SURFACE OF THE MOON.

THAT'S BASICALLY A PIECE OF ROCK FLYING THROUGH SPACE.

THERE ARE ALSO WIDER FLAT PLACES ON THE MOON, AND THAT'S WHERE HUMANS FIRST WENT.

12 MEN HAVE WALKED ON THE MOON AS PART OF THE APOLLO SPACE MISSION.

THIS IS WHAT IT LOOKED AND SOUNDED LIKE WHEN APOLLO 15 LANDED ON THE MOON.

>> YOU COULD LAND OVER HERE.

THERE'S GOOD DUST.

LOOKING GREAT.

>> 60 SECONDS.

>> 40 FEET.

THREE FEET PER SECOND.

LOOKING GREAT.

20 FEET.

CONTACT.

>> AUTO, AUTO.

>> WE'RE ON THE SURFACE.

[CHEERS] >> ROGER.

>> HERE ARE TWO ASTRONAUTS EXPLORE THE MOON'S SURFACE AND COLLECTED MOON ROCKS.

GRAVITY, OR THE FORCE THAT HOLDS YOU DOWN ON EARTH, IS MUCH LESS ON THE MOON, ABOUT ONE-SIXTH AS STRONG.

COULD YOU STILL FALL DOWN, BUT IT'S EASIER TO BOUNCE BACK UP.

THERE'S NO WATER OR WEATHER ON THE MOON, AND THERE'S NO AIR.

BECAUSE THERE'S NO AIR, THE MOON IS TOTALLY SILENT.

THE MOON HAS A LONG DAY AND A LONG NIGHT, EACH LASTING ABOUT TWO WEEKS.

IT CAN GET PRETTY HOT AND PRETTY COLD ON THE MOON.

IN THE DAYTIME, THE TEMPERATURE RISES TO ABOUT 250 DEGREES FAHRENHEIT.

THAT'S HOTTER THAN BOILING WATER.

IN THE NIGHT, THE MOON GETS ICY COLD, ABOUT 290 DEGREES BELOW ZERO.

ASTRONAUTS MADE SPECIAL SUITS TO PROTECT THEM AND TO COPE THEM THE RIGHT TEMPERATURE.

THEY ALSO CARRY TANKS OF AIR ON THEIR BACKS SO THEY CAN BREATHE W NO AIR OR WATER AROUND, THE MOON'S SURFACE HAS CHANGED VERY LITTLE.

SO SCIENTISTS CAN LEARN LOTS ABOUT HOW IT WAS FORMED.

THESE ASTRONAUTS FOUND SOMETHING INTERESTING WHEN THEY EXPLORED PART OF THE MOON CALLED FRAMOROW.

>> VISIBLE FROM THE ARM PITS UP RIGHT NOW.

>> NOTHING LIKE BEING UP TO YOUR ARM PITS IN LUNAR DUST.

>> NOT ALL OF THE SURFACE IS THAT DEEP IN MOON DUTION.

THE ASTRONAUTS ALSO COLLECTED 173 POUNDS OF MOON ROCKS AND BROUGHT THEM BACK TO THE SCIENTISTS ON EARTH TO STUDY.

SCIENTISTING LEARN A LOT ABOUT THE MOON BY LOOKING AT ITS ROCKS.

THEY DISCOVERED THE MOON IS ABOUT THE SAME AGE AS THE EARTH.

BUT THE MOON'S SOIL AND ROCKS ARE DIFFERENT THAN OUR PLANET'S.

FOR ONE THING, MOON ROCKS CONTAIN NO WATER, UNLIKE ROCKS HERE ON EARTH.

APOLLO 17 WAS THE LAST SPACESHIP TO CARRY PEOPLE TO THE MOON IN DECEMBER OF 1972.

WHEN THE ASTRONAUTS DEPARTED, THEY LEFT BEHIND A FALCON FEATHER AND A FOUR-LEAF CLOVER.

JUST TO REMIND EVERYBODY OF ALL THE LIVING THINGS HERE ON EARTH.

SCIENTISTS WANT TO GO BACK TO THE MOON TO LEARN MORE FOR THE IMPRINT OF THE SOLAR SYSTEM'S HISTORY CAN BE FOUND ON THE MOON.

AND JOINING ME NOW TO ANSWER YOUR QUESTIONS ABOUT THE MOON ARE TWO SCIENTISTS.

JOINING US IN OUR MOSCOW STUDIO IS JASON BARNES, PROFESSOR OF PHYSICS FROM THE UNIVERSITY OF IDAHO.

THANK YOU FOR JOINING US.

>> THANKS.

>> AND IN OUR BOISE STUDIO IS DARYL MACOMB, ASSOCIATE PROFESSOR OF PHYSICS AT BOISE STATE UNIVERSITY.

>> THANKS, JOAN.

>> WE WANT TO HEAR FROM YOU.

CALL US AT 1-800-973-9800 OR EMAIL US AT D4K@IDAHOPTV.ORG, OR TWEET US AT @D4KONIDAHOPTV.

WHEN YOU SEND IN A QUESTION, AND YOU YOUR CLASS WILL HAVE A CHANCE TO WIN DVDs AND OTHER PRIZES.

LET'S GO TO OUR FIRST QUESTION FROM MRS.

HUDSON'S CLASS FROM DANIEL, WHO WANTS TO KNOW, WHY IS THE MOON IMPORTANT TO THE EARTH?

>> WELL, THAT'S A LITTLE BIT HARD TO ANSWER.

JASON MIGHT HAVE SOME GOOD THINGS TO SAY ABOUT THAT.

I WOULD SAY IT'S IMPORTANT TO US PARTLY BECAUSE SOME PEOPLE THINK THE MOON ACTUALLY HELPS STABILIZE THE SPIN OF THE EARTH.

AND THAT'S -- IT'S A LITTLE HARD TO UNDERSTAND HOW THAT WORKS, BUT POTENTIALLY THAT'S A BENEFICIAL ASPECT OF THE MOON.

ALSO, OF COURSE, YOU KNOW, WE'RE USED TO THE MOON, IT AFFECTS THE TIDES, LIGHT AT NIGHT, AND SO ON.

AND SO THOSE ARE SOME OF THE REASONS WHY THE MOON IS IMPORTANT TO US.

>> JASON, WHY DO YOU IT THIS MOON IS IMPORTANT TO THE EARTH?

>> I THINK DARYL'S RIGHT.

THE MOON HELPS STABILIZE EARTH'S ROTATION AXIS.

WHAT CAUSES THE SEASONS IS THE TILT OF EARTH'S AXIS, SO WITHOUT THE MOON, OVER LONG TIME SCALES, HUNDREDS OF THOUSANDS OF YEARS, THE INTENSITY OF EARTH'S SEASONS WOULD CHANGE.

MEANING THAT WINTERS WOULD BE COLDER AND SUMMERS WOULD BE WARMER, OR SUBJECTERS WOULD BE LESS WARM AND WINTERS WOULD BE WARMER.

WOULD BE MORE WARM.

AND SO ACTUALLY YOU MIGHT THINK THIS IS A SMALL EFFECT, BUT THE SMALL VARIATIONS WE HAVE RIGHT NOW ARE WHAT CAUSE THE ICE AGES, OR WHAT CAUSES THE GLACIERS TO MOVE FORWARD AND BACK.

SO WITHOUT THE MOON, WE MIGHT ENTER INTO MUCH MORE SEVERE ICE AGE LIKE CONDITIONS AND BACK INTO WARMER CONDITIONS MUCH MORE OFTEN, AND THAT UNSTABLE CLIMATE CAN BE -- CAN'T HELP LIFE FORMS.

>> LET'S GO TO A QUESTION FROM RIVERSIDE ELEMENTARY, MATT WOULD LIKE TO KNOW HOW BIG IS THE MOON?

JASON, WE'LL TOSS IT TO YOU.

>> THE MOON IS ABOUT ONE-FOURTH AS BIG AS EARTH IN SURFACE OF ITS DIAMETER, BUT ONLY 1% AS MASSIVE AS THE EARTH.

SCIENTISTS LOOK AT PLANETS AND MOON AND WE LOOK AT THEIR MASS, ABOUT EQUIVALENT TO YOUR WEIGHT.

SO WE WANT TO KNOW HOW MUCH STUFF THERE IS IN IT.

THE MOON HAS ONLY ABOUT 1% THE MASS THAT THE EARTH DOES, WHICH SOUNDS LIKE NOT VERY MUCH.

BUT COMPARED TO OTHER MOONS IN OUR SOLAR SYSTEM, OURS IS THE BIGGEST MOON COMPARED TO ITS PLANET IN ANY OF THE SOLAR SYSTEM THAT'S NOT AN STEROID OR SMALLER BODY LIKE THAT.

>> WE HAVE A VIDEO CALLER, VIDEO QUESTION, LET'S SEE IF WE CAN GO TO JACK.

>> MY QUESTION IS, HOW DO STARS FORM?

>> WE PUT THAT IN THERE BECAUSE THE MOON FORMED ALONG THE SAME TIME.

>> RIGHT.

WELL, STARS -- FIRST OF ALL, IT'S GOOD TO KNOW THAT STARS ARE FORMING ALL THE TIME.

AND SO STAR FORMATION IS SOMETHING THAT HAS BEEN GOING ON FOR BILLIONS OF YEARS IN OUR GALAXY, AND WILL CONTINUE FOR A LONG TIME.

THE BASIC IDEA IS THAT IT ALL HAS TO DO WITH GRAVITY.

THE SAME THING THAT KEEPS US ATTACHED TO THE PLAN EXPET CAUSES THE MOON TO ORBIT AROUND THE EARTH IS ULTIMATELY THE CAUSE OF STARS FORMING.

IF YOU HAVE A LARGE BALL OF GAS, WHAT IN ASTRONOMY WE CALL A NEBULA, AND IF THERE'S ENOUGH MASS, IF THIS NEBULA IS LARGE ENOUGH, THEN GRAVITY IS GOING TO CONEXPIRE TO SHRINK THIS GAS CLOUD DOWN MORE AND MORE, AND EVENTUALLY YOU BUILD UP MOST OF THE MASS OF THE CLOUD WILL END UP IN THE CENTER, WHERE A STAR IS.

SO THAT'S WHY, FOR INSTANCE, OUR SUN IS BY FAR THE MOST MASSIVE THING IN OUR SOLAR SYSTEM, BY FAR HAS THE MOST MASS, BECAUSE GRAVITY TRIES TO MOVE EVERYTHING INTO THE CENTER.

AND SO GRAVITY DOES MOST OF THE WORK AND AS THE STUFF GOES TOWARDS THE CENTER, THE GASSES GO TOWARDS THE CENTER, THEY HEAT UP AND EVENTUALLY NEW PHYSICAL PROCESSES TAKE OVER, BUT TO STABILIZE IT AND TO STOP FOR A WHILE GRAVITY FROM SHRINKING THE GAS CLOUD, THAT'S WHEN YOU GET A STAR.

>> LET'S GO TO HIRAM IN BOISE.

GO AHEAD.

>> Caller: [INAUDIBLE] >> WHY DOESN'T THE MOON FALL DOWN?

OK.

JASON, GO AHEAD.

>> THE ANSWER IS THE MOON IS FALLING DOWN.

IN FACT, IT WAS A -- IN THE 16 HUNDREDs HE WONDERED WHY THE MOON WASN'T FALLING THE SAME WAY AS THE APPLE FALLS, AND IT IS.

THE FACT THE MOON IS FALLING KEEPS IT IN THAT STABLE CIRCULAR ORBIT AROUND THE EARTH.

AND SO ANY OBJECT THAT'S IN A CIRCULAR ORBIT IS IN THAT ORBIT BECAUSE GRAVITY IS KEEPING IT FALLING IN THAT ORBIT.

SO ACTUALLY, THAT'S WHY ASTRONAUTS WHEN THEY'RE IN THE SPACE STATION OR ON THE SPACE SHUTTLE OR IN FREE FALL, THEY LOOK LIKE THEY DON'T HAVE ANY GRAVITY AT ALL, BUT THE EFFECT OF GRAVITY IS WHAT'S KEEPING THEM IN ORBIT.

>> FROM MRS.

McCAMIRISH'S CLASS, CHRISTIAN WANTS TO KNOW CAN THE MATERIALS BE REMOVED FROM THE EXPHOON TAKEN BACK TO EARTH TO STUDY?

OF COURSE WE'VE DONE THAT ALREADY.

CAN YOU TELL ME ABOUT THAT?

>> THAT'S ONE OF THE GREAT THINGS ABOUT EXPLORING THE MOON.

WE'VE HAD THE CHANCE FOR HUMANS TO GO THERE AND ACTUALLY BRING MATERIALS BACK.

AND IT'S HARDER, THE FARTHER AWAY SOMETHING GETS IN GENERAL THE HARDER IT IS TO STUDY.

IT'S HARD TO STUDY DISTANT STARS, BECAUSE THE INFORMATION WE GET IS REALLY IN THE FORM OF JUST LIGHT.

BUT IF WE CAN SEND THINGS THERE, LIKE PROBES GOING TO NEARBY PLANETS, THEN THAT SORT OF ALLOWS YOU TO DO SORT OF BETTER AMOUNT OF STUDY, AND THEN IF YOU CAN ACTUALLY SEND HUMANS THERE, THAT OF COURSE IS A WAY TO GET THE MOST INFORMATION BACK.

BUT WE'RE FORTUNATE THAT WE'VE BEEN ABLE TO GO TO THE MOON AND BRING THIS STUFF BACK.

>> AND WHAT'S ON THE DARK SIDE OF THE MOON?

JASON, THE ONLY -- WE ONLY SEE PART OF THAT.

AND WE HAVE A QUESTION ABOUT THAT TOO.

WHAT'S ON THE DARK SIDE?

>> WELL, THE DARK SIDE OF THE MOON IS SORT OF A MISNOMER.

THE DARK SIDE OF THE MOON IS THE NIGHT SIDE OF THE MOON AND THE DARK SIDE OF THE MOON IS WHICHEVER HALF IS NIGHT AT A GIVEN TIME, AND IN GENERAL, HALF THE MOON IS DAY AND HALF IS NIGHT, BUT WHICHEVER HALF IS WHICH KEEPS CHANGING.

THERE IS, HOWEVER, A FAR SIDE OF THE MOON, SO THE NEAR SIDE OF THE MOON IS THE SIDE WE CAN SEE AND THE FAR SIDE OF THE MOON IS THE SIDE WE CAN'T SEE.

AND THERE ACTUALLY IS QUITE A BIG DIFFERENCE BETWEEN THE NEAR SIDE AND THE FAR SIDE OF THE MOON.

IF YOU LOOK AT THE NEAR SIDE, YOU SEE THE DARK SPLOTCHES, AND THOSE DARK SPLOTCHES ARE LAVA PLAINS LIKE THE DARK ROCK WE HAVE UP NEAR MOSCOW AND DOWN IN THE SNAKE RIVER PLAINS, AND THAT'S THE SAME STUFF, MADE OF BASALT.

THE FAR SIDE OF THE MOON IS ALL BRIGHT, THERE'S HARDLY ANY DARK MATERIAL, SO THE FAR SIDE OF THE MOON LOOKS LIKE THE BRIGHT SIDE OF THE NEAR SIDE OF THE MOON.

>> OK.

WE HAVE A QUESTION FROM JERRY, WHO IS HOME SCHOOLED WHO WOULD LIKE TO KNOW, HAS ANYONE BEEN ABLE TO FILM IT WHEN A METEOR HIT THE MOON TO MAKE A CRATER?

>> I DON'T KNOW THE ANSWER TO THAT.

MAYBE JASON DOES.

>> WE'VE BEEN LOOKING REALLY HARD FOR THAT.

THAT'S A GOOD QUESTION.

DURING METEOR STORMS, A LOT OF SCIENTIST AND AMATEURS AS WELL TAKE VIDEO CAMERAS THAT LOOK AT THE MOON LOOKING FOR SPECIFIC IMPACTS TO HAPPEN.

AND WE HAVE TO THIS -- AT THIS POINT WE HAVE NOT YET SEEN AN ACTUAL METEOR HIT THE MOON.

HOWEVER, WE HAVE -- WE'RE GOING TO BE LOOKING FOR THE APOLLO ASTRONAUTS IN THE LATE 1960s TOOK A BUNCH OF PICTURES OF THE MOON WHILE THEY WERE ORBITING AROUND.

RIGHT NOW WE HAVE ANOTHER SPACECRAFT ORBITING THE MOON THAT'S TAKING MUCH BETTER HIGH RESOLUTION PICTURES.

SO ONE OF THE THINGS WE'RE GOING TO DO IS COMPARE THE PICTURES THE APOLLO ASTRONAUTS TOOK 50 YEARS AGO, TO THE NEW PICTURES THAT ARE TAKEN TODAY AND WE'RE HOPING TO SEE SOME DIFFERENCES AND NEW CRATERS THAT HAVE FORMED IN THE INTERIM TO BE ABLE TO COUNT HOW MANY CRATERS HIT THE MOON AT ANY GIVEN TIME.

>> I THINK -- I WAS THINKING WE HAD -- MAYBE I'M THINKING IT WAS MARS OR SATURN WE SAW HIT.

>> JUPITER.

YEAH.

>> LET'S SEE -- GO AHEAD.

>> GO AHEAD.

>> LET'S GO TO A QUESTION FROM MRS.

CHASEY'S CLASS, ADRIAN WOULD LIKE TO KNOW, WHY DOES THE MOON HAVE SO MUCH WATER TO PULL ON THE WAVE AND TIDES BUT DOES NOT PULL UP OTHER STUFF FROM THE EARTH?

>> THE MOON DOES PULL UP EVERYTHING.

THERE'S A TIDE -- THERE WAS A MOON -- THERE IS A TIDE IN THE EARTH'S OCEAN AND THERE'S A TIDE IN THE LAND AS WELL.

AND THE TIDE IN THE LAND IS A LITTLE SMALLER BECAUSE THE LAND RESISTS BEING PULLED, IT HAS STRENGTH.

WHEREAS THE OCEAN DOES NOT.

BUT EVERYTHING GETS PULLED BY THE MOON BACK AND FORTH.

THE LAND, THE WATER, THE AIR, BUT ALL TO DIFFERING AMOUNTS.

THAT'S WHAT WE PERCEIVE AS THE TIDE, BECAUSE THE OCEANS GET PULLED MORE, YOU SEE THAT EFFECT MORE.

>> WE'RE BEING PULLED TOO, WE JUST DON'T REALIZE IT BECAUSE IT'S IN RELATION TO EVERYTHING ELSE AROUND US.

>> RIGHT.

>> OK.

FROM NATALIE, WE HAVE -- WHY DO WE HAVE DIFFERENT SHAPES OF THE MOON?

I ASSUME SHE'S TALKING ABOUT THE DIFFERENT -- HOW WE SEE THE MOON IN DIFFERENT PHASES.

>> DIFFERENT SO-CALLED PHASES.

THE FIRST POINT IS WHAT JASON MENTIONED EARLIER, THAT ALL THE TIME NO MATTER WHAT WE SEE, HALF OF THE MOON IS IN SUNLIGHT, AND HALF IS DARK.

AND SO THE REASON WE SEE DIFFERENT PHASES, WHAT WE'RE SEEING FROM OUR PERSPECTIVE, WE'RE SEEING THE SHADOW OF THE MOON JUST FROM DIFFERENT POSITIONS.

WHAT'S REALLY IMPORTANT IS WHERE THE MOON IS WITH RESPECT TO THE EARTH AND THE SUN.

SO AS THE MOON ORBITS AROUND THE EARTH, THE SUN IS A LONG WAYS AWAY.

AND SO WHATEVER SIDE OF THE MOON THAT'S FACING THE SUN IS, THAT'S THE BRIGHT SIDE.

THAT'S THE ILLUMINATED SIDE.

AND SO WHEN THE MOON IS BETWEEN US AND THE SUN, THEN THE ILLUMINATED SIDE IS FACING COMPLETELY AWAY FROM US.

BUT THEN AS THE MOON ORBITS AROUND, EVENTUALLY WE START TO SEE THE ILLUMINED SIDE MORE AND MORE, AND UNTIL EVENTUALLY YOU GET A FULL MOON, AND THAT'S WHEN THE MOON IS ON THE OPPOSITE SIDE OF THE EARTH FROM THE SUN.

AND THEN SLOWLY IS AS IT CONTINUES ITS ORBIT, THE FACE IS REVERSED AND YOU GET LESS ILLUMINATION TO A NEW MOON.

AND SO IT REALLY HAS TO DO WITH WHERE THE MOON IS WITH RESPECT TO THE DIRECTION TO THE SUN, AND THEREFORE WHAT PART OF THE ILLUMINATED SIDE WE'RE SEEING, REALLY.

>> LET'S GO TO OUR NEXT VIDEO QUESTION, FROM DANIEL.

>> MY NAME IS DANIEL, I GO TO DARWIN ELEMENTARY SCHOOL, AND -- DALTON ELEMENTARY SCHOOL, AND MY QUESTION IS, WHY DO WE ONLY SEE ONE SIDE OF THE MOON?

>> WE JUST TALKED ABOUT THAT, HOW WE ARE IN RELATIONSHIP TO THE EARTH.

>> RIGHT.

IT HAS TO DO WITH THE MOON'S ORBIT, BUT IT'S A VERY SPECIFIC THING.

IT'S NORMAL TO THINK THAT SINCE WE SEE THE SAME SIDE OF THE MOON ALL THE TIME, THAT THE MOON DOESN'T SPIN AROUND.

BUT IN FACT THE MOON DOES SPIN AROUND.

IT'S JUST SPINNING AROUND AT THE SAME RATE AT WHICH IT'S ORBITING AROUND US.

SO, FOR INSTANCE, IF YOU TRIED -- YOU COULD DO A SIMPLE THING IN THE CLASSROOM, FOR INSTANCE, IF YOU HAVE SOMEONE STAND IN THE MIDDLE OF THE CLASS, AND THEN YOU WALK AROUND THAT PERSON, AND IF YOU'RE ALWAYS FACING THAT PERSON, YOU HAVE TO BE ROTATING AROUND IN ORDER TO KEEP YOUR FACE ALWAYS TOWARDS THAT PERSON.

AND SO WE SEE THE SAME SIDE ALL THE TIME BECAUSE IT'S SPINNING AT THE SAME RATE AT WHICH ITS ORBITING.

>> LET'S GO TO OUR NEXT VIDEO QUESTION, FROM ATHENA.

>> HI.

I GO TO DALTON ELEMENTARY.

MY QUESTION IS, HOW IS THE MOON MADE OUT OF THE SAME MATERIAL AS THE EARTH?

>> JASON?

>> WELL, IT TURNS OUT IT HAS TO DO WITH WHERE THE MOON CAME FROM.

ALL THE PLANETS, THE INNER APPELLANTS, MERCURY, VENUS, EARTH, AND MARS, ARE MADE OF THE SAME KIND OF STUFF IN THE SENSE THEY'RE ALL MADE OF ROCK.

HOWEVER, THE MOON IS MADE OF VERY NEARLY THE SAME STUFF AS THE EARTH, ALMOST EXACTLY THE SAME WHEN YOU LOOK AT THE ACTUAL CHEMISTRY OF THE CHEMICALS THAT MAKE UP THE MOON ROCKS.

AND THE REASON FOR THAT IS WHERE THE MOON CAME FROM.

WE NOW KNOW THAT THE REASON -- THE -- WHAT FORMED THE MOON, WHERE THE MOON CAME FROM WAS FROM A GIANT IMPACT ON THE EARTH.

SO AS THE EARTH WAS STILL FORMING, THERE WAS A GIANT PROA TOE PLAN THEAT WAS ABOUT THE SIZE OF MARS, ABOUT 10 TIMES MORE MASSIVE THAN THE PRESENT MOON THAT SMACKED INTO THE EARTH AND THE DEBRIS THAT WAS THROWN UP BY THAT HUGE IMPACT WAS IN ORBIT AROUND THE EARTH AND EVENTUALLY COALESCE AND BECAME THE MOON.

SO THE MOON IS MADE OF THE SAME STUFF AS THE EARTH BECAUSE THE MOON AND EARTH ARE BOTH MADE UP OF STUFF IN THE MOON -- BOTH THE EARTH AND THAT GIANT OBJECT THAT HIT THE EARTH AT THE TIME THE MOON'S FORMATION 4.5 BILLION YEARS AGO.

>> WE HAVE A QUESTION FROM CALI, WHO WOULD LIKE TO KNOW, WHY IS SO IT COLD ON THE MOON AT NIGHT?

>> THAT IS REALLY TWO THINGS.

TEMPERATURE ON THE SURFACE IS KIND OF INVOLVES HOW FAST AN OBJECT ROTATES AND WHETHER OR NOT THERE'S AN ATMOSPHERE.

AND SO WITH THE MOON, THERE'S NO ATMOSPHERE, AND THE ATMOSPHERE HELPED SPREAD THE HEAT OUT AROUND THE PLANET.

AND THE MOON IS ROTATING VERY SLOWLY.

IT TAKES ROUGHLY FOUR WEEKS FOR THE MOON TO SPIN AROUND ONCE.

AND SO THERE'S NO ATMOSPHERE TO SMOOTH THE HEAT OUT, AND SO FOR A COUPLE WEEKS AT A TIME PART OF THE MOON WILL BE FACING THE SUN.

AND THEN FOR ANOTHER COUPLE WEEKS, IT WILL BE FACING AWAY FROM THE SUN.

DAY VERSUS NIGHT.

AND SO FOR THE SAME REASON, THEN, THAT WE HAVE COLD NIGHTS AND HOT DAYS HERE, WE HAVE COLD NIGHTS AND HOT DAYS ON THE MOON, BUT THEIR LACK OF AN ATMOSPHERE, THE MOON'S LACK OF AN ATMOSPHERE MAKES IT MUCH MORE EXTREME.

>> QIET LIKE TO KNOW, WHY DOES JUPITER HAVE TWO MOONS?

IS JUPITER JUST GREEDY?

>> JUPITER ACTUALLY HAS A NUMBER OF MOONS.

PROBABLY 60.

WE ACTUALLY HAVE LOST COUNT.

WE HAVEN'T LOST COUNT, BUT WE KEEP GETTING -- FINDING MORE AND MORE MOONS AROUND OTHER PLANETS, SPECIFICALLY JUPITER.

JUPITER HAS FOUR BIG MOONS ABOUT THE SIZE OF OUR MOON THAT ARE PRETTY SUBSTANTIAL, THOSE AR, THOSE ARE BIG MOONS THAT ARE BIG SUBSTANTIAL PLACES.

THE OTHER OF 50 JUPITER'S 55 SOME-ODD MOONS ARE ALL KIND OF SMALL CHUNKS OF ROCK, ONLY 10 OR 20 MILES ACROSS.

SOME OF THEM ARE CHUNKS OF ICE.

AND THE REASON IT HAS SO MUCH MORE IS THAT JUPITER AND SATURN AND THE OTHER PLANETS FORMED VERY DIFFERENTLY THAN THE EARTH DID.

JUPITER AND SATURN FORMED FROM A GAS THAT WAS SUCKED IN BY GRAVITY AND IT WAS DOING SO, IT FORMED A DISK OF MATERIAL THAT FORMED THESE MOONS, WHERE EARTH'S MOON WAS FORMED BY THIS GIANT IMPACT.

SO THE FACT JUPITER AND SATURN HAVE MORE MOONS, OWES TO THE FACT THOSE MOONS WERE FORMED DIFFERENTLY AND BY A MORE EFFICIENT MOON FORMING MECHANISM THAN THE GIANT IMPACT WAY OUR MOON WAS MADE.

>> LET'S GO TO KATY IN BOISE.

GO AHEAD.

ARE YOU THERE, KATY?

>> Caller: AM I ON?

>> YOU ARE ON.

WHAT'S YOUR QUESTION?

>> Caller: I WAS WONDERING IF THE MOON CIRCLES -- WHY DOES THE MOON CIRCLE THE EARTH?

>> SO WHAT PUT IT THERE AND WHY IS IT THERE?

>> WELL, JASON DESCRIBED A LITTLE BIT ABOUT HOW THE MOON CAME ABOUT, PROBABLY BECAUSE OF THE COLLISION, BUT WHAT KEEPS IT ATTACHED TO US, WHAT KEEPS IT ORBITING AROUND US IS THE SAME FORCE THAT WE TALKED ABOUT THAT IS RESPONSIBLE FOR BUILDING STARS.

AND THAT'S GRAVITY.

SO GRAVITY IS -- IT'S SOMEWHAT INTERESTING, GRAVITY COMPARED TO OTHER FORCES LIKE ELECTRICITY IS A VERY, VERY WEAK FORCE, BUT IN SITUATIONS WHERE WE HAVE BIG MASSES LIKE THE EARTH AND MOON, GRAVITY IS VERY IMPORTANT.

AND SO THE GRAVITATIONAL ATTRACTION BETWEEN THE EARTH AND MOON THAT KEEPS THE MOON BOUND TO US.

>> WE DID HAVE A WHOLE SECTION OF OUR "D4K" SITE JUST TALKING ABOUT GRAVITY.

SO IF YOU HAVE QUESTIONS ABOUT GRAVITY, CHECK OUT THE "D4K" WEBSITE.

WE DID ONE WHOLE SHOW JUST ON GRAVITY.

WE HAVE A QUESTION FROM JESSE IN MRS.

HUNT'S FOURTH GRADE CLASS, WHAT IS THE MOON MADE OF, AND JASON, WHILE YOU ANSWER, I ALSO WANT TO KNOW, THERE'S NO -- THERE ARE NO WATER IN THE ROCKS BUT HAVE THEY FOUND WATER IN ANY FORM ON THE MOON?

>> SO THERE'S A COUPLE GOOD QUESTIONS.

THE MOON IS MADE OF MOSTLY ROCK.

SAME AS THE EARTH IS MADE OF.

HOWEVER, THE ROCKS ARE SLIGHTLY DIFFERENT.

THE DARK STUFF THAT YOU'RE LOOKING AT WHEN YOU LOOK AT THE FACE OF THE MOON IS MADE OF BASALT AND THAT'S ALMOST THE EXACT SAME STUFF BENEATH MY FEET RIGHT NOW HERE IN MOSCOW AND DOWN THERE IN THE SNAKE RIVER PRINCE RAINIER IF YOU DRIVE ALONG THE HIGHWAY YOU'LL SEE DARK BLACK ROCKS THAT YOU CAN SEE ALONGS THE HIGHWAY, THOSE ARE BASALT ROCKS.

AND THAT'S THE SAME STUFF THAT THE DARK PARTS OF THE MOON ARE MADE OF.

THE LIGHTER PARTS OF THE MOON, HOWEVER, ARE MADE OF DIFFERENT COMPOSITION ROCK, HIGHER IN PARTICULAR CHEMICALS, AND THAT BRIGHTER STUFF WAS FORMED WHEN THE MOON DID.

SO WHEN THE MOON FORMED, IT WAS EXTREMELY HOT.

WHEN THE MOON FORMED IT WAS SO HOT, IT WAS ENTIRELY MELTED.

SO THE WHOLE MOON WAS MADE OF MELTED ROCK.

IT WAS A HUGE LAVA MOON.

AT THAT TIME THE FIRST STUFF THAT STARTED TO SOLIDIFY FLOWED INTO THE DISPOP THAT FORMED THE BRIGHT PARTS OF THE MOON AND SO THE BRIGHT PARTS OF THE MOON ARE MADE UP OF A SLIGHTLY DIFFERENT COMPOSITION RORK THAT FLOATED TO THE TOP OF THE GIANT LAVA OCEAN 4.5 BILLION YEARS AGO.

BECAUSE THE MOON FORMED SO HOT IN THAT ENCOUNTER WITH THE OBJECT THAT FORMED IT WHEN -- WHEN THAT BIG MARS SIZED BODY SLAMMED INTO THE EARTH, THAT DROVE ALL THE WATER AWAY FROM THE HOT LAVA THAT FORMED THE MOON.

SO THE APOLLO ASTRONAUTS WHEN THEY BROUGHT BACK SAMPLES DIDN'T FIND ANY WATER AT ALL IN THOSE LUNAR SAMPLES.

HOWEVER, WE NOW KNOW THAT THERE IS SOME WATER ON THE MOON.

THERE'S JUST A TINY BIT OF WATER IN THE UPPER SURFACE LAYER OF THE MOON THAT'S VERY LOOSELY BOUND CHEMICALLY AND DOESN'T FORM A HUGE FRACTION OF THE MASS, SO IT'S NOT VERY MUCH STUFF BUT IT'S A LITTLE BIT OF WATER IN THE TOP PART OF THE MOON.

AT THE LUNAR SOUTH POLE THERE SEEMS TO BE WATER.

AS DARYL WAS SAYING, THE DARK SIDE OF THE MOON, THE NIGHT SIDE OF THE MOON GETS VERY COLD.

THERE HAPPENS TO BE A CRATER, A FEW CRATERS NEAR THE SOUTH POLE OF THE MOON THAT NEVER SEE DAYLIGHT THERE.

ARE PLACES WHERE THEY'RE IN PERMANENT NIGHT.

SO BECAUSE THEY'RE IN PERMANENT NIGHT, NOT ONLY DO THEY GET REALLY COLD, THEY GET REALLY, REALLY COLD.

THE COLDEST PLACE THAT WE HAVE YET FOUND IN THE SOLAR SYSTEM IS NOT PLUTO, THE COLDEST PLACE WE'VE MEASURED IN THE SOLAR SYSTEM IS THE SOUTH POLE OF THE MOON WHERE THE TEMPERATURE IS ABOUT 30 DEGREES KELVIN, 400 DEGREES BELOW ZERO FAHRENHEIT.

IT'S SO COLD MRS.

A BUNCH OF TRAPPED WATER AND OTHER CHEMICALS THAT NORMALLY YOU THINK OF AS GASSES ARE TRAPPED IN THESE CRATERS AT THE SOUTH POLE OF THE MOON, AND SO BECAUSE THERE'S WATER THERE, ONE OF THE THINGS -- IDEAS THAT PEOPLE HAVE, IF WE SEND PEOPLE BACK TO THE MOON IT MIGHT BE CHEAPER FOR THEM TO MINE WATER AT THE CRATERS AT THE SOUTH POLE THAN BRING WATER THEMSELVES.

THERE IS SOME WATER ON THE MOON, NOT VERY MUCH, BUT THERE'S A LOT IN THE PERMANENTLY SHADOWED REGIONS AT THE POLE.

>> I WANT TO MAKE SURE, WE HAVE A COUPLE PEOPLE ON THE PHONE, SO SAMUEL, STAY WITH US, AND WE'LL ANSWER YOUR QUESTIONS WHEN WE FLIP OVER TO THE OTHER SIDE ON OUR WEB-ONLY PROGRAM.

SO IF YOU'RE ON THE PHONE NOW, STAY WITH US AND WE'LL GET TO YOU.

GENTLEMEN, THANK YOU.

I APPRECIATE YOU BEING HERE.

DARYL IN BOISE, JASON IN MOSCOW.

IF YOU WANT TO KNOW MORE, CHECK OUT OUR WEBSITE, AND YOU CAN EXPLORE LOTS OF INFORMATION ABOUT THE MOON, CHECK IT OUT AT IDAHOPTV.ORG.

CLICK ON "D4K."

LAST MONTH'S WINNER IN OUR QUESTION CONTEST WAS OLIVIA AT DALTON ELEMENTARY.

REMEMBER, WHEN YOU ?END A QUESTION, YOU AND YOUR CLASS CAN WIN OR CONTEST.

THANKS FOR JOINING US.

WE'LL SEE YOU NEXT TIME ABOUT -- TALKING ABOUT FLIGHT ON OUR NEXT SHOW.

WE'LL SEE YOU THEN.

THANKS FOR JOINING US.

HAVE A GOOD WEEKEND.

WE'LL SEE YOU NEXT TIME ON "D4K."

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