Latest / Space Nuts: Astronomy Insights & Cosmic Discoveries / Martian Meteorites, Gas Giants & The Search for Alien Life | Q&A

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Martian Meteorites, Gas Giants & The Search for Alien Life | Q&A · Space Nuts: Astronomy Insights & Cosmic Discoveries

• 0:00
  Speaker 1: Hello again, thanks for joining us. This is a Q
• 0:02
  Speaker 1: and A episode of Space Nuts where we answer astronomy
• 0:06
  Speaker 1: and space science questions from our audience. Today. David wants
• 0:10
  Speaker 1: to know about Mars meteor showers. Penny is asking about
• 0:15
  Speaker 1: fly through emissions for Satin and Jupiter that could be messy.
• 0:19
  Speaker 1: Andy is asking about the gravitational effect of Jupiter on
• 0:23
  Speaker 1: its moons, particularly Europa. And Duncan wants to talk about
• 0:28
  Speaker 1: alien civilizations. We will deal with all of that and
• 0:32
  Speaker 1: more on this episode of Space Nuts fifteen in Channal
• 0:37
  Speaker 1: ten nine Ignition sequence Space Nuts NY or three two
• 0:47
  Speaker 1: Space Nuts. As Can I reported, Bill's good. This is
• 0:52
  Speaker 1: Fred Watson's favorite segment. He's back again for more. Professor
• 0:56
  Speaker 1: Fred Watson, Astronomer at Large, Hello, Hello Andrew, you I
• 1:00
  Speaker 1: am quite well. It's been a long time, like an
• 1:03
  Speaker 1: anatu or three minutes.
• 1:07
  Speaker 2: I hope nobody's guests that we record these impairs. But
• 1:10
  Speaker 2: never mind, never mind.
• 1:11
  Speaker 1: If they haven't figured it out by now, they probably
• 1:14
  Speaker 1: never will.
• 1:16
  Speaker 3: That's right.
• 1:17
  Speaker 1: I'm pretty sure most people know how it works. I mean,
• 1:20
  Speaker 1: they just have to look at the shirts we're wearing
• 1:21
  Speaker 1: every week. That's if they do it on the YouTube channel. Well,
• 1:26
  Speaker 1: I don't know if I don't know if they put
• 1:27
  Speaker 1: the video on anymore, because it could be could be
• 1:31
  Speaker 1: a bit of a turn off. So I don't know. Anyway,
• 1:36
  Speaker 1: all is well with you, I trust it is. Thank you. Yes,
• 1:39
  Speaker 1: I I already knew the answer, but we have to
• 1:41
  Speaker 1: ask because you know, this is just to be that light. Yes,
• 1:44
  Speaker 1: that's exactly. Why don't we try and answer some questions? Oh?
• 1:49
  Speaker 1: Or if you must, well you do it. I'm just
• 1:52
  Speaker 1: going to push them in there. Let's go to our
• 1:55
  Speaker 1: first question that comes from David.
• 1:57
  Speaker 3: Kind of a Compson here otly Spring in the UK,
• 2:03
  Speaker 3: Back to Mars. As a child of the fifties and sixties,
• 2:08
  Speaker 3: reading the comics at the time, there was always a
• 2:13
  Speaker 3: risk of meet your showers. I'm just wondering, given that
• 2:19
  Speaker 3: Mars atmosphere is not as dense as the IRBs, what
• 2:25
  Speaker 3: are smaller meteorites would be able to hit the surface
• 2:31
  Speaker 3: of Mars and be a real hazard to anybody put
• 2:39
  Speaker 3: in the house there. Find the podcast absolutely amazing. Everybody,
• 2:45
  Speaker 3: have a great day. Bye.
• 2:48
  Speaker 1: Thank you David, Thanks for those kind words. I'm glad
• 2:50
  Speaker 1: you're enjoying the podcast. Sorry, way back to Mars I
• 2:54
  Speaker 1: didn't push him there. I didn't. Everyone knows a lot
• 2:57
  Speaker 1: of Mars, but yeah, your shows it makes up. It
• 3:02
  Speaker 1: brings up an interesting point. It's got a much less
• 3:05
  Speaker 1: significant atmosphere than Earth. So does that mean smaller things
• 3:09
  Speaker 1: can get through?
• 3:11
  Speaker 2: It does, Yeah, it does. David's absolutely right. I'm delighted
• 3:17
  Speaker 2: we've got a listener in hot and this spring. I
• 3:20
  Speaker 2: used to drive past there very very frequently. It's between
• 3:23
  Speaker 2: Durham and Sunderland in the north of England, and I
• 3:27
  Speaker 2: was a very very regular user of the A one
• 3:30
  Speaker 2: m which goes us taught and the spring. And it's
• 3:34
  Speaker 2: lovely to hear your voice, David, and hear that lovely
• 3:37
  Speaker 2: North Durham accent there. The answer is yes, so because
• 3:43
  Speaker 2: the atmosphere, you know, the atmospheric pressure on Mars is
• 3:46
  Speaker 2: I think it's point six percent of our atmospheric pressure,
• 3:49
  Speaker 2: which means that meteorites coming in are going to have
• 3:52
  Speaker 2: a lot less resistance. We know of meteorites on Mars,
• 3:57
  Speaker 2: many have been identified by both Curious City and Perseverance, usually.
• 4:02
  Speaker 1: By there but by their color.
• 4:04
  Speaker 2: But both those rovers were equipped with lasers appas that
• 4:09
  Speaker 2: could give us an idea of the content and some
• 4:11
  Speaker 2: of those meteorites have been found to be metallic. So
• 4:14
  Speaker 2: meteorites on Mars are something that happens. And yes, there's
• 4:17
  Speaker 2: probably a higher risk of damage from an incoming meteorite
• 4:22
  Speaker 2: on Mars than on Earth because the likelihood is but
• 4:28
  Speaker 2: their terminal velocity, the sort of final velocity after they've
• 4:32
  Speaker 2: passed through the atmosphere, will be much higher than it
• 4:36
  Speaker 2: will be on Earth just because of a lot lower pressure.
• 4:39
  Speaker 2: And so yes, meteorite protection might turn out to be
• 4:44
  Speaker 2: quite an important aspect of putting humans on Mars. We
• 4:47
  Speaker 2: haven't had any reports of you know, there's how many
• 4:52
  Speaker 2: rovers have been on Mars now, I can think of
• 4:55
  Speaker 2: long two, three, four, five, six, at least six, probably
• 4:59
  Speaker 2: more like seven or eight. They are Andrew is googling
• 5:05
  Speaker 2: it as we speak.
• 5:06
  Speaker 1: Yeah, six six rovers. Sojournal, Spirit, opportunity, curiosity, perseverance, and Jurong,
• 5:15
  Speaker 1: the Chinese mission.
• 5:16
  Speaker 2: The Chinese one. That's right, Yeah, so I did get
• 5:19
  Speaker 2: the right answer.
• 5:20
  Speaker 1: Six.
• 5:20
  Speaker 2: Yeah, yeah, it's so none of those, as to the
• 5:27
  Speaker 2: best of our knowledge, has suffered any kind of meteoritic impact.
• 5:31
  Speaker 2: So at least, so far, so good in terms of
• 5:34
  Speaker 2: our understanding of the meteorite hazard on Mars. But a
• 5:39
  Speaker 2: good question to raise, David, and it's always always gives
• 5:42
  Speaker 2: us a chance to talk about Mars.
• 5:44
  Speaker 1: He did ask about the danger to housing on Mars.
• 5:49
  Speaker 1: They probably won't build houses on Mars like they do
• 5:52
  Speaker 1: on Earth. And because of the radiation issues, they're probably
• 5:56
  Speaker 1: going to have to go underground, which would pretend get
• 6:00
  Speaker 1: them from anything like that. But there will be surface
• 6:03
  Speaker 1: something or other there one day, infrastructure. Yeah, perhaps domes
• 6:09
  Speaker 1: that they could be susceptible. Maybe.
• 6:12
  Speaker 2: Yeah, it looks like I mean what we imagine is
• 6:14
  Speaker 2: something like White Cliffs in western New South Wales where
• 6:18
  Speaker 2: people live underground. They do, and that's just to get
• 6:21
  Speaker 2: out of the heat.
• 6:23
  Speaker 1: So that's radiation.
• 6:26
  Speaker 2: Yes, it is silver radiation, that's right.
• 6:29
  Speaker 1: Yeah, indeed, yeah, sort of another question. Yeah, here it is.
• 6:34
  Speaker 1: We are constantly monitoring for big objects that could be
• 6:39
  Speaker 1: threatening to Earth, things that could destroy these cities or
• 6:42
  Speaker 1: regions or god forbid, the planet itself as we know it.
• 6:47
  Speaker 1: What about Mars? Do we keep an eye on anything
• 6:49
  Speaker 1: that might hit that?
• 6:52
  Speaker 2: So yes, to some extent. If you you know, if
• 6:56
  Speaker 2: you can identify near Earth objects look at their orbits,
• 7:01
  Speaker 2: you would certainly find out from the analysis very quickly
• 7:06
  Speaker 2: if there was any risk of one of those hitting
• 7:08
  Speaker 2: the planet Mars. But there's probably many small objects in
• 7:12
  Speaker 2: the vicinity of Mars because it's closer to the asteroid
• 7:14
  Speaker 2: belt than we are, which are undetectable from the distance
• 7:19
  Speaker 2: of Earth. You know, objects that might even be as
• 7:22
  Speaker 2: big as Phoebost, Mars's biggest moon. We would be able
• 7:26
  Speaker 2: to detect that from Earth quite easily, but as we
• 7:29
  Speaker 2: obviously can. It was discovered in the eighteen hundreds. But
• 7:32
  Speaker 2: you know, if you had something that was only a
• 7:35
  Speaker 2: few tensimeters across, which could pose a hazard to houses
• 7:41
  Speaker 2: on Mars, that would be hard to detect from the
• 7:45
  Speaker 2: distance of Earth unless it unless it was also a
• 7:48
  Speaker 2: near Earth object, so it was coming close to closer
• 7:52
  Speaker 2: to our telescopes.
• 7:53
  Speaker 1: Yeah, there'd be nothing much we could do about a
• 7:57
  Speaker 1: beefing hitting Mars anyways, there or they'd be good experiment
• 8:00
  Speaker 1: if we want to test our capabilities.
• 8:01
  Speaker 2: Well, that's right, if there was you know, the bigger
• 8:04
  Speaker 2: ones are the ones that we know more about because
• 8:08
  Speaker 2: they're easier to see. If something like that was looking
• 8:11
  Speaker 2: as though it might collide with Mars, yes, it might
• 8:15
  Speaker 2: be a good time to test out the theories that
• 8:18
  Speaker 2: were put into place with the Dart mission a few
• 8:20
  Speaker 2: years ago. Yes, see, whether it'll actually work on something
• 8:23
  Speaker 2: a bit bigger.
• 8:23
  Speaker 1: Than that, one can only wonder, And hopefully we don't
• 8:28
  Speaker 1: ever have to put it to the test for ourselves.
• 8:31
  Speaker 1: But you just never know. There's always something going on
• 8:35
  Speaker 1: out there. There's so much stuff bumping into it. There's
• 8:38
  Speaker 1: something else out there. It's only a matter of time
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  Speaker 1: before one of them kareems into our sector and becomes
• 8:45
  Speaker 1: a potential threat. Although we seem to be finding them
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  Speaker 1: more and more now, don't we.
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  Speaker 2: Frere with And that's the good news parts of this story.
• 8:53
  Speaker 2: Two good news sides of this story. One is that
• 8:55
  Speaker 2: the big ones are the easiest to find, and the
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  Speaker 2: other is that we've been finding these things now for
• 9:00
  Speaker 2: the last forty years and have a good idea of
• 9:03
  Speaker 2: what this environment's like.
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  Speaker 1: Yep, great to hear from you, David. Great question and
• 9:08
  Speaker 1: thanks for sending it in. Our next question comes from Penny.
• 9:12
  Speaker 1: It's a short, quick one. I think I know where
• 9:16
  Speaker 1: this one might go to in terms of an answer.
• 9:18
  Speaker 1: As Satin and Jupiter are gas giants, are there any
• 9:22
  Speaker 1: plans to fly a spacecraft through the Middle of one
• 9:25
  Speaker 1: or both of them. Interesting question, Penny. I do recall,
• 9:30
  Speaker 1: when you're talking about comet or asteroid impact, the impact
• 9:36
  Speaker 1: with Jupiter many many years ago that we almost got
• 9:40
  Speaker 1: footage of it was just quite not quite the right angle,
• 9:43
  Speaker 1: but we did see the aftermath of it.
• 9:46
  Speaker 2: That's Schumacher Levy.
• 9:48
  Speaker 1: Yes.
• 9:48
  Speaker 2: Second, the one Jupiter, Remember what year ninety four I
• 9:53
  Speaker 2: think it might have been. So the issue is that
• 10:01
  Speaker 2: the gas giant aspect of these planets is really just
• 10:05
  Speaker 2: their outer envelope that's gassy, and we don't really know
• 10:09
  Speaker 2: what's underneath that. The likelihood is there will be a
• 10:12
  Speaker 2: solid core there. It may be rocky. Some have suggested
• 10:18
  Speaker 2: that it will be made of metallic hydrogen, which is
• 10:21
  Speaker 2: hydrogen in a very unusual form. So you've got a
• 10:25
  Speaker 2: core of something called metallic hydrogen. So flying through is
• 10:30
  Speaker 2: not anything that's planned because it will be impossible.
• 10:33
  Speaker 1: But even if.
• 10:35
  Speaker 2: These gas giants were sort of gaseous all the way through,
• 10:39
  Speaker 2: it still would be a very hard thing to achieve
• 10:42
  Speaker 2: because you're entering an atmosphere. You'd have to slow the
• 10:47
  Speaker 2: rocket the spacecraft down enormously in order to prevent it
• 10:51
  Speaker 2: from just melting by friction. With the atmosphere, which is
• 10:55
  Speaker 2: what happened to Cassini. Cassini was plunged into Saturn's atmosphere
• 10:59
  Speaker 2: at the end its mission in twenty seventeen. It didn't
• 11:02
  Speaker 2: burn up because there's no oxygen in Saturn's atmosphere, but
• 11:06
  Speaker 2: the friction made it melt. Basically, it just melted and
• 11:08
  Speaker 2: felt pieces. In fact, NASA produced some real tear jerker
• 11:13
  Speaker 2: footage of what that might have looked like, which we
• 11:16
  Speaker 2: saw often at the end of the Cassini mission.
• 11:21
  Speaker 1: You know, this thing which had.
• 11:23
  Speaker 2: Performed valiantly for the previous thirteen years and done a
• 11:27
  Speaker 2: marvelous job at revolutionizing our knowledge not just of Saturn
• 11:31
  Speaker 2: and its rings and moons, but also the way planets
• 11:33
  Speaker 2: form and things like that. This footage of Cassini hitting
• 11:37
  Speaker 2: the top of Saturn's atmosphere and having its antennas ripped
• 11:41
  Speaker 2: off and eventually just melting into becoming part of the
• 11:44
  Speaker 2: atoms of the atmosphere of Saturn, and that is you know,
• 11:49
  Speaker 2: any mission to try and penetrate down through the atmosphere
• 11:54
  Speaker 2: would struggle because of the rapid increase in density, the
• 11:59
  Speaker 2: fact that you've got to slow the spacecraft down in
• 12:01
  Speaker 2: order to stop it just burning up my friction. I
• 12:04
  Speaker 2: think one of the Jupiter missions, I can't remember which
• 12:09
  Speaker 2: one might have been Galileo actually sensed as it hits
• 12:16
  Speaker 2: Jupiter's atmosphere to burn up again or to melt. I
• 12:20
  Speaker 2: think there were sensors on board that were giving us
• 12:23
  Speaker 2: some readings of what the conditions were like.
• 12:26
  Speaker 1: Yeah. I think the other big problem would be pressure,
• 12:31
  Speaker 1: wouldn't it if you tried.
• 12:32
  Speaker 2: To yeap, So the pressure just goes up, probably exponentially
• 12:38
  Speaker 2: at some level.
• 12:39
  Speaker 1: Yeah, and Penny might be interested to know that there
• 12:42
  Speaker 1: are some missions slated for the near future, europea Clipper
• 12:50
  Speaker 1: which will launch in it's already launched, I should recite
• 12:53
  Speaker 1: it's quite yet twenty thirty. There's the Juice mission, which
• 12:58
  Speaker 1: launched in twenty twenty three, which arrives in twenty thirty
• 13:01
  Speaker 1: one and drag and fly with the helicopter off to Totem. Yeah,
• 13:09
  Speaker 1: we'll launch in twenty twenty eight. So they're more interested
• 13:13
  Speaker 1: in some of the moons around those gas giants. But yes,
• 13:19
  Speaker 1: that they are fascinating, and of course we're most interested
• 13:23
  Speaker 1: in Europa Clipper because we want enough anything's living in
• 13:27
  Speaker 1: the ocean, and maybe there is, Maybe there isn't. Who knows,
• 13:32
  Speaker 1: it could just be made of jelly. We don't really know,
• 13:36
  Speaker 1: although the Juice mission is more likely to figure all
• 13:38
  Speaker 1: that out. Boom boom, Thank you, Penny Lovely to hear
• 13:42
  Speaker 1: from you. This is space Nuts Q and a edition
• 13:44
  Speaker 1: with Andrew Dunkley and Professor Fred Watson. Let's take a
• 13:50
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• 15:21
  Speaker 1: space nuts. Okay, we take your space nuts. And speaking
• 15:29
  Speaker 1: of Europa and Jupiter, we've got a question now from Andy.
• 15:34
  Speaker 3: This is Andy the train driver from London.
• 15:36
  Speaker 1: I just got a question about Europa.
• 15:39
  Speaker 4: I know Europa erupts because it's being sort of squeezed
• 15:42
  Speaker 4: by the gravity of Jupiter. But what I don't understand
• 15:47
  Speaker 4: is if Europa is being affected by Jupiter's gravity, why
• 15:51
  Speaker 4: is it not just being pulled closer to Jupiter. I
• 15:55
  Speaker 4: thought gravity pulls things down, like when you throw a
• 15:59
  Speaker 4: ball in air, gravity pulls it back down. I don't
• 16:02
  Speaker 4: understand how Europa is being squeezed. That suggests to me
• 16:07
  Speaker 4: that it's being affected by gravity from all directions. Squeeze
• 16:11
  Speaker 4: it like you could squeeze the tennis ball. Maybe you
• 16:14
  Speaker 4: can shed some light on this or tell me that
• 16:17
  Speaker 4: I'm blocking up the wrong tree.
• 16:19
  Speaker 1: Anyway.
• 16:20
  Speaker 4: Thanks for the podcast, guys, really interesting and see you
• 16:23
  Speaker 4: in the next one.
• 16:24
  Speaker 1: It's Jordie's job to bark up the wrong tree.
• 16:27
  Speaker 2: But nicely done, Andrew.
• 16:33
  Speaker 1: Your point is well taken. Andy. It's not just Europer though.
• 16:36
  Speaker 1: There are several moons orbiting the gas giants that do
• 16:40
  Speaker 1: get that squeeze effect tightened. I think is one of them,
• 16:44
  Speaker 1: and I look probably all of them to some degree.
• 16:48
  Speaker 1: But Europe, yeah, it's it's it's in a difficult position.
• 16:53
  Speaker 1: It's a good question though, why don't they just get
• 16:55
  Speaker 1: sucked in? Doesn't? But we're not a gas giant.
• 17:00
  Speaker 2: No, the same thing happens to our moon though, so
• 17:03
  Speaker 2: it's actually probably I think the moon that and is
• 17:06
  Speaker 2: thinking of his Eo, which is the innermost of the
• 17:10
  Speaker 2: of the moons that the big moon, big four moons
• 17:13
  Speaker 2: of Jupiter, and it is the one that gets the
• 17:15
  Speaker 2: most squeezing and squashing because of its proximity to Jupiter.
• 17:22
  Speaker 2: Europa probably also has the same phenomenon, and there may
• 17:26
  Speaker 2: be eruptions of it on Europa that possibly a bit
• 17:32
  Speaker 2: like Enceladus, where you've got stuff streaming out through the
• 17:35
  Speaker 2: cracks in the in the ice. But the genuine volcanic eruptions,
• 17:40
  Speaker 2: which they really are, it's hot lava, is what takes
• 17:44
  Speaker 2: place on Eo, the innermost of those moons. So the
• 17:48
  Speaker 2: way to understand this is to realize recognize that if
• 17:54
  Speaker 2: you've got an object in a very strong gravitational field.
• 17:58
  Speaker 2: First of all, let me just clarify the reason why
• 18:01
  Speaker 2: objects in orbit around other objects don't just get pulled in.
• 18:05
  Speaker 2: They are getting pulled in, but they've got a forward
• 18:08
  Speaker 2: motion that compensates for the for the pull. So basically
• 18:12
  Speaker 2: the motion of the object through space is what balances
• 18:17
  Speaker 2: out the gravity of a giant like Jupiter. And so
• 18:21
  Speaker 2: that you know, the greater the gravity of a of
• 18:24
  Speaker 2: a planet, the faster its satellites have to orbit in
• 18:27
  Speaker 2: order not to not to fall in. And so that's
• 18:32
  Speaker 2: that's the mechanism that stops these things just immediately being
• 18:36
  Speaker 2: sucked in to Jupiter. They're already moving. And that comes
• 18:39
  Speaker 2: about why are they moving because they were formed that
• 18:42
  Speaker 2: way with the way the you know, the planets and
• 18:45
  Speaker 2: their satellites evolve the way they formed, they're basically swirling
• 18:49
  Speaker 2: around right from the start and that swirling motion is
• 18:52
  Speaker 2: what stops which is fossilized in the in the planets
• 18:56
  Speaker 2: themselves and the moons of the planets, and stops them
• 18:59
  Speaker 2: falling into their parent object. But the squeezing and squashing
• 19:04
  Speaker 2: comes from what we call the tidal effect, and it
• 19:07
  Speaker 2: is actually exactly the same thing that gives rise to
• 19:09
  Speaker 2: tides on the Earth. But let's concentrate for a minute
• 19:13
  Speaker 2: on EO. Here's this little world right next to gas
• 19:17
  Speaker 2: giant Jupiter. One side of EO is feeling the gravitational
• 19:22
  Speaker 2: pull of Jupiter. The other side is as well, but
• 19:26
  Speaker 2: it's feeling slightly less because it's further away, because the
• 19:30
  Speaker 2: gravitational pull falls off as the distant squared one of
• 19:34
  Speaker 2: the distant squared, So further on the further side of
• 19:38
  Speaker 2: EO from Jupiter, it's going to feel less force. And
• 19:42
  Speaker 2: that is what contributes to this tension that there is
• 19:47
  Speaker 2: and basically elongates the planets slightly in the direction of Jupiter.
• 19:51
  Speaker 2: Now why we talk about squashing and squeezing is that
• 19:56
  Speaker 2: throughout the orbit of EO, she's not a planet, it's
• 19:59
  Speaker 2: a subtleite. But around the orbit of EO as it
• 20:02
  Speaker 2: goes around is not circular. So sometimes that force is
• 20:06
  Speaker 2: greater than others. That tension that's trying to pull it apart,
• 20:10
  Speaker 2: it's greater than at other times. And basically it's that
• 20:15
  Speaker 2: squashing stretching really is the best word for it. As
• 20:18
  Speaker 2: it goes round, as it goes around Jupiter. That change
• 20:22
  Speaker 2: in the stretch force that's being applied is what generates
• 20:26
  Speaker 2: the heat that causes these eruptions to continually take place.
• 20:31
  Speaker 2: And that's called the tidal effect. The fact that one
• 20:33
  Speaker 2: side of a body feels a different gravitational force from
• 20:36
  Speaker 2: the other. It's what makes us susceptible if we fall
• 20:39
  Speaker 2: into a black hole to spaghettification. Spaghettification is just a
• 20:43
  Speaker 2: nicer word than tidal effects.
• 20:46
  Speaker 1: Yeah. So you've got a real combination of effected. Yeah,
• 20:49
  Speaker 1: that's right. You've got the gravitational effect, You've got all
• 20:53
  Speaker 1: little dynamics, yeah, or sort of coinciding to keep these
• 20:57
  Speaker 1: things from falling into the planet that there's attack war
• 21:00
  Speaker 1: going on. I saw a really good demonstration online or
• 21:05
  Speaker 1: probably three or four weeks ago on how the tides
• 21:09
  Speaker 1: work on Earth and of because most people, and I
• 21:13
  Speaker 1: must confess guilt here, assume that the Moon causes the
• 21:17
  Speaker 1: water to rise and then fall. But it's not. It's
• 21:20
  Speaker 1: the fact that the Earth is rotating, the Moon is orbiting,
• 21:24
  Speaker 1: and there's always a wave. It's just always there, and
• 21:27
  Speaker 1: it's just that when it when the moon reaches your vicinity,
• 21:32
  Speaker 1: that that lump of water comes up and goes down again.
• 21:37
  Speaker 1: It's it's not the water so much rising, it's just
• 21:40
  Speaker 1: it's always risen in proximity to the moon. Am I right?
• 21:44
  Speaker 2: You are?
• 21:46
  Speaker 1: You're partly right, because it's a bit more you I
• 21:48
  Speaker 1: missed something.
• 21:49
  Speaker 2: Yeah, that doesn't explain the bulge on the other side, because,
• 21:54
  Speaker 2: as you will, you get a high tide every toye
• 21:58
  Speaker 2: and that's because again it's the tidal effect. So the
• 22:03
  Speaker 2: moon's pulling on the ocean on the near side, it's
• 22:06
  Speaker 2: also pulling on the earth itself and that leaves behind
• 22:11
  Speaker 2: the water on the other side, so you get a
• 22:13
  Speaker 2: bulge on each side.
• 22:15
  Speaker 1: That works. Fascinating. It's worth looking up that demo. I
• 22:21
  Speaker 1: didn't really fine print obviously, but yeah, that makes sense.
• 22:24
  Speaker 1: So the water's being poured earth sort of dragging with it,
• 22:28
  Speaker 1: and then the water's been left behind on the other side.
• 22:31
  Speaker 1: So you've got two bulges, two bulges exactly, so fascinating. So,
• 22:36
  Speaker 1: and that's kind of ague. What's happening to all these
• 22:38
  Speaker 1: these moons in various ways. If I have not water,
• 22:41
  Speaker 1: something else has been.
• 22:43
  Speaker 2: Well, that's right, it's the rock, does it as well?
• 22:45
  Speaker 2: The same is true on Earth. The rock goes up
• 22:48
  Speaker 2: and down as well. I've got a question for Andy though,
• 22:51
  Speaker 2: if he's for getting back to us, I'd like to
• 22:54
  Speaker 2: know what sort of trains he drives, because yeah, I'm
• 22:58
  Speaker 2: a bit of a train myself. Of train drivers are
• 23:02
  Speaker 2: my heroes.
• 23:03
  Speaker 1: Yeah, I live next door to a retired train driver.
• 23:06
  Speaker 1: So yeah. But when we flew into Dubbo the other day,
• 23:11
  Speaker 1: I looked down at the rail maintenance facility. It's a
• 23:15
  Speaker 1: brand new system facility that's just been built in Dubbo
• 23:19
  Speaker 1: and they're fitting out all the new regional trains and
• 23:22
  Speaker 1: you can see them all lined up, bright red, all
• 23:25
  Speaker 1: getting ready to go. They're putting all the furniture in
• 23:28
  Speaker 1: them and the Wi Fi systems, and yeah, they'll be
• 23:33
  Speaker 1: rolled out pretty soon, not exactly sure when, but the
• 23:37
  Speaker 1: plan is soon. That's the answer to the question.
• 23:39
  Speaker 2: Officially, have you ridden on a new metro trains here
• 23:45
  Speaker 2: in Sydney, Yes, I have, yes, so you'll know that
• 23:47
  Speaker 2: they drive one hundred kilometers an hour. With new driver.
• 23:50
  Speaker 2: You can stand at the front, look out the front
• 23:52
  Speaker 2: window and pretend you're driving it.
• 23:54
  Speaker 1: And I've done that in a taxi in San Francisco.
• 23:57
  Speaker 1: Oh yes, yehs for rival as taxi. That's next level.
• 24:01
  Speaker 1: That's just amazing. But yeah, yeah, pretty incredible stuff. Thanks. Andy,
• 24:07
  Speaker 1: really enjoyed that question. And yeah, if you want to
• 24:10
  Speaker 1: tell us what sort of train you drive, send us
• 24:11
  Speaker 1: another message. We'd love to find out how their barlow.
• 24:20
  Speaker 3: If I'm Provan.
• 24:28
  Speaker 1: Spiece notutes. Our final question today, Fred comes from Duncan.
• 24:34
  Speaker 1: He said, I've heard that a group of astrophysicists have
• 24:37
  Speaker 1: calculated that there are an estimated one thousand alien civilizations
• 24:42
  Speaker 1: spread across the Milky Way. But the Milky Way is
• 24:45
  Speaker 1: one hundred thousand light years across. How far away would
• 24:48
  Speaker 1: an advanced civilization have to be in practical terms to
• 24:52
  Speaker 1: be uncontactable? In other words, are we realistically given the
• 24:58
  Speaker 1: distances involved actively alone?
• 25:03
  Speaker 2: Yes, is the answer. And it's not just about the distance.
• 25:08
  Speaker 2: It's also about the time. Because a thousand civilizations with
• 25:14
  Speaker 2: in a galaxy that's twelve billion years old, they might
• 25:18
  Speaker 2: well have turned up and gone long ago or still
• 25:21
  Speaker 2: be in the future.
• 25:22
  Speaker 1: Because assume that we all coexist.
• 25:25
  Speaker 2: That's right, and we probably don't. There's actually a really
• 25:28
  Speaker 2: nice piece. Now let me see if I can find
• 25:31
  Speaker 2: it to direct Duncan to it. It's on one of
• 25:37
  Speaker 2: the space the science media came he today is actually.
• 25:41
  Speaker 1: I think is Oh where is it? Sorry, I've lost it.
• 25:46
  Speaker 2: Yeah, it's basically a summary of thinking by the likes
• 25:51
  Speaker 2: of Richard Feynman and other great minds. And the bottom
• 25:57
  Speaker 2: line is, it's exactly what I've been saying. It's not
• 25:59
  Speaker 2: just the distances, it's the time that you're the era
• 26:05
  Speaker 2: in which you live, and it's very unlikely that we'd
• 26:09
  Speaker 2: find communicable civilizations within the same time zone that we're
• 26:16
  Speaker 2: living in, if I can put it that way. It's
• 26:18
  Speaker 2: actually on. It is on again on the brighter side
• 26:21
  Speaker 2: of news, and the headline is a really very very
• 26:25
  Speaker 2: thoughtful article, well worth a read. Interstellar travel is impossible
• 26:29
  Speaker 2: and aliens haven't visited the Earth, physicists say, and it's
• 26:32
  Speaker 2: because the laws of physics basically make any kind of
• 26:36
  Speaker 2: travel or even communication extremely difficult. The laws of physics
• 26:41
  Speaker 2: are very rigid, worth having.
• 26:43
  Speaker 1: A look at. Yeah, indeed, although there's this new book
• 26:46
  Speaker 1: that I know that's been written that kind of is
• 26:49
  Speaker 1: counted all that. But you can do that in science fiction.
• 26:54
  Speaker 2: Quite so that's why it's called science fiction.
• 26:59
  Speaker 1: Yes, that's what it is. By way of example, though,
• 27:03
  Speaker 1: if I may duncan, if you were to be aware
• 27:08
  Speaker 1: of an advanced communicative civilization on a rocky planet orbiting
• 27:14
  Speaker 1: Alpha centaury A, for example, and you sent them a message,
• 27:20
  Speaker 1: it would take I'm just trying to remember four point
• 27:24
  Speaker 1: three seven years to get there, and that means a
• 27:28
  Speaker 1: return message. If they answered you immediately, would mean that
• 27:33
  Speaker 1: you would not get a reply for eight point seven
• 27:35
  Speaker 1: four years, give or take. But let's round that out
• 27:39
  Speaker 1: though a decade, because you know what the bureaucracy is
• 27:41
  Speaker 1: like around Alpha Tory. They're not going to you know,
• 27:44
  Speaker 1: they're going to take a couple of years to figure
• 27:46
  Speaker 1: out what they want to say. But that's the reality
• 27:51
  Speaker 1: of it, isn't And that's our nearest potential, ye neighbor,
• 27:57
  Speaker 1: It's true.
• 27:58
  Speaker 2: And I mean the point that this article makes is,
• 28:03
  Speaker 2: you know, we live in a bubble of radio radio radiation,
• 28:07
  Speaker 2: which are all the transmissions from Earth that's now basically
• 28:11
  Speaker 2: one hundred light years in radius because we've been sending
• 28:16
  Speaker 2: radio transmissions for about a hundred years and all right,
• 28:20
  Speaker 2: what's that one hundred divided? But it's a thousandth of
• 28:23
  Speaker 2: the diameter of the galaxy, and so you know, it's
• 28:26
  Speaker 2: hardly any distance at all. So yeah, it's in a
• 28:33
  Speaker 2: way and uncomfortable reality. To all intents and purposes. We're alone,
• 28:38
  Speaker 2: We're uncontactable. We are alone. It's good side because we're
• 28:42
  Speaker 2: unlikely to be picked on by any voracious aliens.
• 28:47
  Speaker 1: But yep, yeah, yeah, I think we've got to be
• 28:51
  Speaker 1: realistic about it. Even if there are a thousand alien
• 28:55
  Speaker 1: civilizations with advanced technology in our gal see, we are
• 29:02
  Speaker 1: probably never going to be in a position to communicate
• 29:04
  Speaker 1: with them more and certainly not be able to travel
• 29:07
  Speaker 1: to them in any meaningful way. And so even if
• 29:13
  Speaker 1: we're not alone, we are alone.
• 29:15
  Speaker 2: Yes, that's right exactly. You know that of that thousand civilizations,
• 29:22
  Speaker 2: maybe five hundred of them have been and gone and
• 29:23
  Speaker 2: five hundred of them are yet to evolve.
• 29:28
  Speaker 1: Do you concur with that estimation or you don't think.
• 29:32
  Speaker 2: It's I look, I have seen similar figures being quoted.
• 29:37
  Speaker 2: Not that there's that number of civilizations, but that there
• 29:40
  Speaker 2: might be that sort of number of habitable planets that
• 29:43
  Speaker 2: might be earth like. We don't know whether being earth
• 29:48
  Speaker 2: like necessarily means you evolve an intelligent species because it's
• 29:53
  Speaker 2: done it once.
• 29:53
  Speaker 1: But but yeah, the only time could be because the
• 29:57
  Speaker 1: circumstances have to be perfectly right. Although you know, we're
• 30:00
  Speaker 1: assuming humanoid type, carbon based life forms, but there could
• 30:04
  Speaker 1: be others out there that were created a completely different way. Yeah.
• 30:08
  Speaker 1: So yeah, that's the stuff of imagination at the moment.
• 30:12
  Speaker 1: But it's a possibility, I suppose. And of course we'll
• 30:15
  Speaker 1: look like Dill's next week when a massive alien mothership
• 30:20
  Speaker 1: sets itself down on top of the White House and.
• 30:24
  Speaker 2: To rescue us all.
• 30:26
  Speaker 1: Maybe maybe. Gosh, thanks Duncan. Thanks to everybody who's said
• 30:32
  Speaker 1: in questions, please send them in to us. I do
• 30:35
  Speaker 1: have a bit of homework, sort of. We got a
• 30:37
  Speaker 1: question twice now I've received it from Mike in New York. Mike,
• 30:42
  Speaker 1: you sent us a question in about black holes, an
• 30:45
  Speaker 1: audio question. The whole guts of the question got cut
• 30:49
  Speaker 1: off somehow, and so we got the first We got
• 30:52
  Speaker 1: your pre amble, then you started asking the question. Then
• 30:54
  Speaker 1: there was about five hours of nothing, probably about twenty
• 30:59
  Speaker 1: seconds and then we heard you say goodbye. So we
• 31:01
  Speaker 1: don't actually have the question, so if you'd like to
• 31:04
  Speaker 1: send it again, please do. I don't know what happened there,
• 31:08
  Speaker 1: but yeah, it's the internet, so that's what happened there.
• 31:12
  Speaker 1: But yeah, Mike would love to get that question so
• 31:15
  Speaker 1: we can run with it and any questions you want
• 31:18
  Speaker 1: to send in via the Ask Me Anything tab at
• 31:20
  Speaker 1: the top of our website Spacenuts podcast dot com, Space
• 31:23
  Speaker 1: Nuts dot io, and don't forget to tell us who
• 31:27
  Speaker 1: you are and we're from. Thank you. Fred has always
• 31:29
  Speaker 1: been a lot of fun.
• 31:31
  Speaker 2: Absolutely, it's great questions. Good to hear everybody's voice and
• 31:34
  Speaker 2: nice to see those questions.
• 31:36
  Speaker 1: Thank you. Indeed, that's Professor Fred Wat's an astronomer at
• 31:39
  Speaker 1: large and thanks to heu in the studio. Couldn't be
• 31:43
  Speaker 1: with us today. He got stopped by border security and
• 31:46
  Speaker 1: they realized he was an alien. It comes from New Zealand,
• 31:49
  Speaker 1: that made sense, So he's been arrested. He might be
• 31:52
  Speaker 1: back next week and from me Andrew Uncley, thanks for
• 31:54
  Speaker 1: your company. We'll catch you on the next episode of
• 31:57
  Speaker 1: Space Nuts. Bye bye, SUTs. Been listening to the Space
• 32:01
  Speaker 1: Nights podcast, available at Apple Podcasts, Spotify, iHeartRadio, or your
• 32:08
  Speaker 1: favorite podcast player. You can also stream on demand at
• 32:12
  Speaker 1: fights dot com. This has been another quality podcast production
• 32:16
  Speaker 1: from nights dot com.