Mysteries of the Moon

01Our interaction with the moon over human history mirrors technological advances that we've made here on the Earth.

02The first observations of the moon, the ancients, when they looked up and saw light and dark areas, that was the very first scientific observation because just to see that there are differences there tells you something happened.

03Then the invention of the telescope and the advancement of telescopes that let you look closer.

04And then we get to the space age and we send our first rockets and then we send Apollo and we send astronauts to the surface.

05In that very, very narrow window of time, our complete understanding of Earth's history, of the moon's history, of solar system's history transformed.

06And I expect that with this next era of lunar exploration that we'll have similar fundamental revisions in our understanding of how things work.

07This is NASA's Curious Universe.

08Our universe is a wild and wonderful place.

09I'm your host, Patti Boyd, and in this podcast, NASA is your tour guide.

10Most of what we know about our universe, we've learned through data and imagery from spacefaring technology or ground-based telescopes.

11But there's one planetary body humans have had the chance to study from the surface.

12The moon.

13The moon is our closest celestial friend, staying nearby in our Earth's orbit and impacting life here in so many ways.

14When it's visible, it's the brightest object in the night sky.

15And for as long as humans have looked up, it's captivated our imaginations.

16So let's explore the moon.

17What we've learned over centuries of science, and why we are so fascinated with this constant yet changing cosmic companion.

18We know more about the moon than we know about most other objects in the solar system because we have the benefit of having been there.

19That's Noah Petro, a lunar research scientist and moon enthusiast.

20Our moon is a fascinating fixture for us here on Earth.

21Technically speaking, it's a natural satellite, smaller than a planet, but bigger than an asteroid.

22And just like the man-made satellites we send into space, the moon stays in orbit because of Earth's gravitational pull.

23Most planets in our solar system, and even some asteroids, have a moon.

24The moon is unique in our sky.

25Everything else we can see – planets, stars, meteors – are all small little pinpricks of light.

26But the moon is a main feature.

27So it's not surprising that for centuries, scientists have wanted to learn more about it.

28The moon is a rocky object.

29It is a geologist's paradise.

30From ancient astronomers spotting lunar details through a telescope in 1609, to astronauts setting foot on the surface with the Apollo 11 mission in 1969, we've been studying the mysteries of the moon from many vantage points.

31And we realized there was a lot to learn – not only about space, but about our home planet.

32It is roughly the same surface area as the continent of Africa.

33The rocks that we've brought back from the Apollo program, the rocks that we can understand from looking at the moon with different instruments, are similar to rocks that we have here on the Earth.

34We know that the dark areas that we see from the Earth are similar to rocks that we see in Hawaii or Iceland.

35The bright surface on the moon, the ancient crust of the moon, is a rock called a northosite.

36We see places in Montana, upstate New York, that have a northosite as well.

37So the moon is made of rocks that are similar to things that we see here on the Earth, but the moon is very different than the rocks that we see here on Earth as well.

38And so it's a wonderful contrast and comparison to the rocks that we have here on our home planet.

39The composition of the moon can teach us about our Earth today, but it also provides a unique place to study processes that the Earth doesn't experience very often.

40The Earth has a protective layer between us and space, our atmosphere.

41So a lot of space things that might hit us, like meteors and asteroids, burn up instead.

42The moon is unprotected, so it is constantly bombarded by space debris, from tiny micrometeorites to larger rocks, and each impact results in a crater.

43Every place we go on the Earth tells us something about how the world works, how the Earth has worked today or in the geologic past.

44But there's one process that's not well represented on the Earth, and that's impact cratering.

45And that's when a meteorite or a comet strikes the surface of a planet, and you go to the moon, and you can learn about impact cratering.

46It's a fundamental process that happens everywhere in the solar system that's not well represented here on Earth, because we have this wonderful atmosphere to protect us, we have plate tectonics, we have erosion, and so those features disappear with geologic time.

47But on the moon, they're preserved.

48And so when you study the moon, you get a window into not only what's happening today, but what happened four and a half billion years ago, just after the planets formed.

49And there's a record that's on the lunar surface that is absent, effectively, here on the Earth.

50I'm Casey Honeyball.

51I'm a NASA Postdoctoral Program Fellow at NASA Goddard Space Flight Center, and I study the moon looking for water on the surface.

52Casey is also a lunar scientist.

53She uses telescopes to track different chemicals and particles on our moon's surface.

54The moon is made of all kinds of elements and layers.

55So how exactly did the moon come to exist?

56So the moon is believed to have formed from a giant impact, a Mars-sized object impacting the Earth, which would have then created a lot of debris in a ring around the Earth, which would eventually collect together to form the moon.

57That's right.

58The moon is made of Earth.

59Billions of years ago, around four and a half billion to be exact, scientists think an emerging planet collided with a very young and still-forming Earth, sending debris out into orbit.

60As all those Earth rocks swirled around, they collected into a hot and molten mass and eventually formed what we now see as one solid, rocky object.

61Our moon.

62The moon currently isn't changing very much, so the surface we see today we will see for a very long time.

63But over the moon's lifetime, which is like 4.5 billion years, it's changed drastically.

64It went from being a molten body with no solid surface to a solidified surface that would have big comets and asteroids impacting it, which would create the dark patches and the light patches that we see on the moon today.

65The moon is a pretty large body.

66It's actually one of the largest satellites in our solar system.

67So it's got a lot of rocky locations, but it also has a lot of surface area that is covered with lunar dust or regolith.

68Regolith is a really fun word for moon dust.

69Generally, the term regolith means any kind of dusty, rocky material.

70It's a scientist's description of choice for the fine, thin particles that cover the lunar surface.

71Not only is the moon our window to the solar system, it also greatly impacts life here on Earth.

72The gravity of this large satellite pulls on the Earth as it orbits, causing all sorts of natural phenomena we might take for granted.

73The moon controls our tides.

74So without the moon, our tides would be very weak.

75We wouldn't have big surfing waves that people like to do those crazy stunts on.

76So when the moon is on one side of the Earth, it creates a bulge on that side.

77So it basically pulls the water towards the moon.

78And as the moon rotates, that bulge is going to follow the moon, which is what creates our tides.

79The moon also controls our time of day.

80So without the moon, our days would be much, much shorter.

81And then because we have the moon and it's gravitationally bound to the Earth, it controls our seasons as well.

82The Earth's mass isn't distributed perfectly evenly across the planet's surface.

83This uneven distribution causes Earth to wobble as it spins around the sun on its axis.

84But the pull of the moon's gravity balances out some of that wobbling, making our climate here on Earth more stable and livable.

85With the moon having such an impact on our daily lives, scientists have been pretty keen to answer fundamental questions.

86So we've developed really cool ways to learn more about our next-door neighbor.

87Some of the major ways that we study the moon is using remote sensing.

88So spacecraft or telescopes here on Earth that can look at the surface of the moon or the space environment around the moon.

89I use the NASA Infrared Telescope Facility on Mauna Kea in Hawaii.

90And I use the NASA Stratospheric Observatory for Infrared Astronomy, SOFIA, which is an airborne telescope.

91And using these two things, I look for signatures of water on the surface of the moon.

92My day-to-day is basically either planning observations on those two telescopes or looking at the data that was collected from the telescopes.

93The wonderful thing about studying the moon is that we can apply almost any technique to studying it.

94From taking a rock that was brought back by an Apollo astronaut and analyzing its age, its composition, its history.

95To looking at data taken from satellites that orbit the moon.

96To take a look at a picture of the lunar surface and try to reconstruct its history.

97That's NOAA asking the interesting questions lunar scientists study every day.

98What is it made of?

99What is its composition?

100What does that composition tell us about how this area formed?

101How it changed over time?

102How old is it?

103And if this feature is young or old, what does that tell us about how the moon has changed in its life?

104The moon might seem pretty calm from here on Earth.

105Going about its phases logically and predictably.

106But it's actually pretty active underground.

107Just like the Earth experiences seismic activity and changes, so does the moon.

108We know that because of the measurements that were made during the Apollo exploration of the moon, that the moon does have seismic activity.

109It has moon quakes.

110It rings like a bell when it's struck by a meteorite.

111There are properties of the lunar interior that suggest maybe there's still some liquid outer core.

112But maybe there's not.

113So we can apply all of the same types of science that we do on the Earth.

114Volcanology, seismology, and apply them to the moon.

115And indeed, one of the things that we do is try to understand the Earth better so that we can understand the moon.

116And apply that understanding then onto Mars and so on and so forth.

117The moon is our friend in space, but it isn't always visible to us.

118It is always there, in a constant orbit, but it goes through eight distinct phases over the course of an Earth month.

119You're probably familiar with these phases already, though some of their names are a little strange.

120The invisible new moon, the waxing crescent, the first quarter, waxing gibbous, the bright full moon, and then the waning gibbous, last quarter, waning crescent, and new moon once again.

121And the naming doesn't end there.

122For centuries, people have tracked full moons and named them based on their months and seasons.

123These include the wolf moon, the strawberry moon, and even the worm moon.

124Monthly moon phases are visible to everyone on Earth, no matter what side of the planet you're on, though they might look upside down depending on your hemisphere.

125That's because the shape we see depends on what part of the sun is reflecting off the moon during its orbit around Earth.

126When the moon is between the sun and Earth, the side facing us can't reflect any sunlight.

127But when the moon is on the other side of Earth, away from the sun, its whole face is lit up.

128This monthly dance of sun, moon, and Earth has helped people for generations keep track of the year, plan important events in agriculture, and keep the allure of the moon alive.

129If the moon always looked the same way, every night, same place, same spot, always looked the same, it would just fall into the background.

130Because the moon changes, its appearance in the sky changes.

131And because we have lunar eclipses where the moon all of a sudden takes on a different color, oh my goodness.

132I think that sparks our curiosity and some emotional response as well.

133And so whether it's the desire to go off and write poetry or talk about how you feel, it's comforting as well.

134It's a constant reminder that we're not alone.

135And again, it's a rock, it doesn't know, but it is there and it feels comforting, at least to me.

136And that's wonderful because it then becomes not just the scientific object, but part of literature, part of art, part of culture.

137The moon changes a lot of things about life here on Earth.

138But what if we were to live on the moon?

139How would life be different?

140Depending on where you are on the moon, the sun goes up for 14 and a half days and goes down for 14 and a half days.

141The poles of the moon, the sun goes up for longer and shorter times.

142So just the day-night rhythm is going to be completely different.

143And depending where you are on the surface of the moon, it could be wildly different.

144Obviously, the temperature ranges extremes on the moon are far different.

145So that's why having good spacesuits, having good habitats are so important.

146And then, of course, there's just the complete mind blowing.

147Oh, the sky is dark.

148There's no blue skies.

149There's no weather.

150The gravity is also one sixth that of the Earth.

151And so you'd find moving around very different.

152You can pick up things that are heavy on the Earth.

153You know, the Apollo astronauts, they were on the moon for as long as three days.

154They found it challenging to figure out how to move around.

155You know, they had difficulties judging distances.

156If you or I were to go to the moon, we'd spend the first few minutes just sort of getting our sea legs under us, our moon legs under us.

157All with a constant reminder that, oh, yeah, it's very dark.

158There's the sun.

159The sky is dark.

160There's the Earth.

161Okay, high Earth.

162Now, when we go to the far side of the moon or even some places at the South Pole where you can't see the Earth, that's going to be quite the thing you need to get adjusted to.

163But that's part of exploring is going past that next hill and losing sight of home.

164My name is Jacob Bleacher.

165I'm the chief exploration scientist for NASA.

166And I make sure that our astronauts can take science and science activities when they go to the moon.

167Jacob has one of the coolest titles here at NASA.

168He's a chief exploration scientist.

169He's thinking about all the ways we can take science off our home planet and into space.

170My job is to make sure that as we build our spacecraft and landers and rovers and robots to go explore the moon, that we take science along for the ride.

171Number one thing we want to do when we get there is scientific research to understand the moon, our Earth, our solar system, and basically our place in the universe.

172The biggest leap in lunar discoveries was made during the space race of the 1960s.

173When astronauts stand on the surface of the moon, they will be part of what President Kennedy called the most hazardous and dangerous and greatest adventure on which man has ever embarked.

174Humans went farther than we'd ever gone before, breaking from Earth's atmosphere and setting our sights on the moon with the Apollo missions.

175So we were challenged to go to the moon in the 1960s in part to show we could, right?

176It's a huge technological jump.

177Big challenges are what really drives big technological advances.

178And so that challenge was given to NASA and it pushed us forward.

179Many things that you have in your house today spun out of the technology we developed to meet that challenge.

180From cordless power tools and advancements in computing to reflective insulation, there are tons of space race tech that probably made it into your home.

181Did you know the cordless dust buster vacuum was originally created to bring back samples from the lunar surface?

182But we also went to learn.

183The Apollo missions went to the moon and were able to collect some of the material from the surface, make observations.

184But there was a whole lead up to Apollo.

185We had a spacecraft series called Ranger that actually crashed into the moon because we had some big questions.

186Would things sink into that like quicksand or would we actually be able to interface with that surface and support a big heavy lander?

187We landed a series of landers called Surveyor.

188And so those were robotic landers that went and landed on the surface.

189Combining these together with orbiters we sent to go around the moon, we were able to collect a good bit of data that helped us understand what we were seeing and how to design the vehicles and the suits and the payloads to go there and do the jobs we were asking.

190And so we go through these phases where we learn and each time we make new observations, there's a big pulse of new learning.

191And then the samples and data we had have been studied for decades following that.

19224 people have been to the moon on missions that ran between 1969 and 1972.

193But since the 1960s and 70s, we've made even more advances in our understanding of the moon, including a particularly exciting chemical discovery made only a few years ago.

194When we went in Apollo, you can see from pictures, it's pretty desolate and it looks really dry and it is very, very dry.

195But we've learned since then that there's actually water on the moon.

196In some places that's little molecules of water mixed in with the grains and they kind of get stuck and trapped in with them.

197But we also think there's actually some vast stores of water trapped inside impact craters or big holes in the ground at the polar regions.

198So places that never see sunlight.

199And so this was kind of a big pulse of new knowledge for us to understand.

200And it's actually driving what we're doing with the Artemis program, which is going to the south pole of the moon to learn more about that water history of the moon.

201Casey was the scientist who made the original discovery of water on the sunlit surface of the moon.

202NASA announced that discovery recently in 2020.

203So I was actually a graduate student at the University of Hawaii sitting in my house when I first saw this feature.

204I think I was actually on the phone with my graduate advisor being like, I don't know what's happening with the data.

205Like it's some, it's doing something weird.

206I'm not, I don't know what is happening.

207He suggested me do one little thing.

208And so I did that in my code and I hit enter and then boom, there's the signal.

209And I'm pretty sure he screamed because it was pretty exciting, right?

210Like we hadn't really been able to determine whether or not water was on the surface of the moon in sunlit regions.

211Before that.

212And so it was a pretty exciting moment for both me and my graduate advisor.

213When we went to publish the paper, Sophia and NASA were very excited about it.

214And that made it all just very overwhelming and exciting.

215NASA is now beginning the journey back to the moon with the Artemis program.

216This program, the sister of the Apollo missions, will take humans to the moon and eventually onto Mars.

217But we're not exactly going back to where we went in the 60s and 70s.

218We're exploring a whole new region of our mysterious cosmic friend.

219The south pole of the moon really is a bold new area that we've never been to.

220The lighting there is very different.

221If you have seen pictures of Apollo, we were able to take advantage of a very repetitive cycle of light and dark.

222Just like here on Earth, you have days and nights.

223On the moon there's a similar cycle.

224But even here on Earth, when you go closer to the poles of a planet or a moon or a satellite, the lighting gets a little different.

225You can have permanent darkness if you go into low lying terrain.

226You can have places that are mostly sunlit.

227But what's really complicated is 100 yards that way or 100 yards that way, that ratio can be different.

228So it really is a new, really bold challenge for us to go and explore the south pole.

229What we're doing here is a continuation.

230It's exploring the moon.

231This is a whole exploration strategy.

232Apollo was part of it.

233Artemis is part of it.

234There will be future explorers, hopefully some folks listening right now, who will be part of it.

235The moon continues to fascinate us as humans and explorers.

236It's the next frontier for life in space.

237And it reminds us that we're all connected here on planet Earth.

238As we look to the future of lunar exploration, we can't wait to see what the next generation of explorers will find.

239What questions they'll ask.

240And what mysteries our moon still holds.

241This is NASA's Curious Universe.

242This episode was written and produced by Christina Dana.

243Our executive producer is Katie Atkinson.

244The Curious Universe team includes Maddie Arnold and Michaela Sosby, with support from Carolyn Capone and Juliette Goodconnect.

245Our theme song was composed by Matt Russo and Andrew Santaguida of System Sounds.

246Special thanks to Nancy Neal Jones, Molly Wasser, and the Planetary Communications team.

247If you liked this episode, please let us know by leaving us a review, tweeting about the show at NASA, and sharing NASA's Curious Universe with a friend.

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249Still curious about NASA?

250You can send us questions about the episode or a previous one, and we'll try to track down the answers.

251You can email a voice recording or send a written note to NASA-CuriousUniverse at mail.nasa.gov.

252Go to nasa.gov slash curiousuniverse for more information.

253If we had two moons, well, they would definitely be fighting for the tides, right?

254And also depends on how big the other moon is.

255If the other moon is pretty small, and its gravitational pull isn't very strong, then our moon would dominate it.

256You probably wouldn't notice very many effects.

257But if the second moon was pretty large, comparable to the moon, they would definitely fight for the tides.

258Both of them would be pulling on that water, so your tides would be very different.

259And then the rotation of the Earth would also be different, because the moon is slowly taking away our spin.

260So if you have two, and they're both pulling on the Earth, maybe our days would be even longer?

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