0:00

This is a Triple J Podcast. Hello.

0:02

Welcome back to Science with Dr. Karl,

0:04

where this week we were joined by

0:06

radio astronomer and science communicator, Dr. Laura

0:09

Dreesen from the University of Sydney. Laura

0:12

absolutely blew my mind in

0:14

this episode. We found out

0:16

about spaghettification, whether

0:18

there is beef between astronomers

0:21

and astrologers, and if

0:23

shooting stars are happening in real time.

0:26

I'm Lucy Smith. Let's get into it. This

0:30

morning, we have a very exciting guest

0:32

joining us on this year Thursday, Dr.

0:36

Laura Dreesen from the University of

0:38

Sydney, who is a radio astronomer,

0:40

science communicator. And Laura, you are

0:42

using some of the biggest telescopes

0:44

to look at the stars, but these are some of

0:46

the biggest telescopes in the world. Tell us a bit

0:48

about the work that you do. They

0:50

are, and I'm even more excited to say

0:52

that a lot of them are here in

0:55

Australia. And most people don't know that we

0:57

have an absolutely fantastic big telescope over in

0:59

Western Australia, about eight hours from Perth called

1:01

ASCAP, as well as a couple of other absolutely

1:03

fantastic instruments over there. So it's really exciting to

1:05

be able to use Australian instruments. We love being

1:07

the best and doing the biggest. We really are.

1:09

And I think we don't talk about it because

1:12

most of our telescopes are really far away from

1:14

people. So you can't just like go for a

1:16

drive and see a telescope. So it's a bit

1:18

hard to say we're the best. Trust us. You

1:21

can't see the telescopes, but trust me, they're there.

1:23

So we really are the top of the world

1:25

with radio astronomy. So what have you been looking

1:27

at recently? So I do a couple of things

1:29

like most scientists, I can't be contained,

1:32

but I mainly work on searching

1:34

for radio stars and searching

1:36

for mystery things, particularly we call them transients.

1:38

And these are things that flash, appear, disappear.

1:40

We see them once, maybe never again, or

1:42

we see them a few times. So those

1:45

are the sort of the main areas that

1:47

I investigate. What is a radio star? So

1:50

it's a star that emits radio light.

1:52

I know we're on the radio, but

1:54

radio is actually kind of light, not

1:56

sound. So it's the lowest frequency of

1:58

light, very low energy. go

2:00

down to red and then you keep going to infrared,

2:02

then you go to millimeter, then to microwave

2:04

and then your radio. So it's right down

2:06

the bottom and it basically tells us that

2:08

these stars have big magnetic field so they're

2:10

like giant magnets. Our Sun is a radio

2:13

star but only because it's so close. If

2:15

we put it a bit further away we wouldn't

2:17

be able to see it. So as far as

2:19

radio stars it's a bit of a small fry

2:21

but the stars that I'm talking about have huge

2:24

magnetic fields, big plasma bursts, lots of exciting things

2:26

happening with these stars. Wow. Now

2:28

I should explain here that astronomers are

2:30

weird. So Dr. Astronomer how

2:36

many elements are there in the periodic table? Well

2:38

for scientists there's only a couple, it's only

2:41

three and most of them are metals. Okay

2:43

so everybody else thinks there's

2:45

90-something elements in uranium and gold and

2:47

lead and all that sort of stuff

2:49

and you think that there's three. There's

2:51

hydrogen and helium and

2:54

metal and everything else. Okay that's

2:56

the first odd

2:58

thing about astronomers. The second one is

3:00

that you call that entire electromagnetic

3:03

spread from you know microwaves and

3:05

TV and radio and ultraviolet and

3:07

gamma rays, you call it light.

3:10

Yes, everybody else in the universe calls light the

3:12

stuff that you can see with your eyeball. Yep

3:14

that's it. Okay now we're going to come to

3:16

the shameful secret that we uncovered a while ago.

3:18

Firstly how many radio astronomers are there in the

3:20

world? Oh that's a good question.

3:23

I mean it's a few hundred radio. A few hundred okay

3:25

and when we did our podcast a few years ago on

3:27

shirtless of science, Dr. Laura

3:30

how many radio stars are there that we knew

3:32

back then? Only a couple of hundreds

3:34

so I mean there's probably still more radio astronomers

3:36

but there's more radio astronomers. So you

3:39

sort of decide look I've

3:41

spent the next 10 years doing this while I go

3:43

off and then I'll have a cup of coffee and

3:45

then come back in 10 years. No. Well yes I

3:47

mean I was a student for a while there so I

3:49

did have to come back a little bit later. But there's more

3:51

than just radio stars there's also

3:53

galaxy. Yes one of the key things that radio

3:55

astronomers love to look at and we can't really avoid looking

3:57

at them which is one of my problems is... holes.

4:00

Black holes, if you look up at the

4:02

night sky, we see dots and they're almost

4:04

all stars. Our radio telescopes also see heaps

4:06

of dots and they're almost all black holes

4:08

at the centres of very distant galaxies. Right,

4:12

okay so we should dive in, dive straight

4:14

into the questions for you. Yes, let's do

4:16

it. You have a real page, oh by

4:18

the way, how many radio stars do we

4:20

know now maybe? So there's about three to

4:22

four hundred before this moment but I've been working

4:25

for the last couple of years on a project

4:27

to find new ones and I've more than doubled

4:29

that number in the last couple of years

4:31

of research. You, an individual person,

4:34

you have doubled, you and your

4:36

team, yes and the excellent team that I work with, have

4:38

doubled what we know. Yes, oh my

4:41

god, big it up for Laura, hooray

4:43

Laura, yeah. Also Bailey who's texted in

4:45

saying you Laura are the

4:48

radio star. Oh wow, thank you. I

4:51

am also a superstar of STEM from Science and

4:53

Technology Australia so I am also a superstar. Oh

4:55

my god, you're making the rest

4:57

of us look good. Okay, we've got

4:59

Laura and Collaroy here. Now Laura you're

5:02

kicking us off, what's your question? Yeah,

5:05

hi doctors. I'm wondering

5:07

if we see stars in the

5:09

past, do we see shooting

5:11

stars in the past or real

5:13

time? I absolutely love

5:15

this question, thank you for the question doctor. So this

5:19

tags into a few different physics things and

5:21

we see, you're right, we do see stars

5:23

in the past. Even our own Sun, the

5:25

light that you're seeing from the Sun right

5:27

now is actually from eight minutes ago. So

5:29

we're definitely seeing stars in the past, the closest

5:32

star is Proxima Centauri. Doctor Collaroy you might have

5:34

to tag in with the exact distance for that one. Four and a bit

5:36

light years. Four and a bit light years, so Proxima

5:38

Centauri, when we see light from that it

5:40

took four years to get to us. But

5:42

the key difference here is that shooting stars

5:44

aren't stars. It's a little astronomy

5:47

quirk that we tend to name things really

5:49

badly. It's one of the things that we

5:51

do, we're very good at it. And a

5:53

shooting star is actually a lump of something

5:55

rock from space that hit our atmosphere and

5:57

burned up. So we are seeing that very...

6:00

close to real time. So time

6:02

still, the light still takes time to travel to

6:04

us from the atmosphere to earth, but it's a

6:06

really short amount of time. So shooting stars are

6:08

so close to us and they're lumps of rock

6:10

burning up. But there have been

6:12

cases of people seeing

6:14

a shooting star which becomes visible

6:17

at maybe 90 kilometers up and

6:20

simultaneously hearing a crackling.

6:24

I emphasise simultaneously because I had instruments and it

6:26

turned out that it was putting out radio waves

6:28

and you were picked up by a barbed

6:30

wire fence about 10 metres from them and then

6:33

transmitting only the 10 metres to them rather than

6:35

90 kilometres down. I was going to say, because sound

6:37

is so much slower than light. I'd expect that you'd hear the, if

6:40

you were to hear something, that that sound

6:42

would be slower. But if it's actually the

6:44

radio wave, then it's light. If it's 90

6:46

kilometres, then that's multiplied by three,

6:48

270 seconds. That's a

6:50

couple of minutes. Exactly. Wow. We've

6:53

got Paul in Sydney here. Dr. Paul, you got a question about

6:55

telescopes. Hi,

6:57

doctors. I was just

6:59

wondering, is it true that there's not

7:01

a telescope powerful enough on Earth to

7:04

see the remnants of the lunar missions

7:06

on the Moon? That is

7:08

true. The telescopes are very powerful and

7:11

they're also far away. However, we have

7:14

a less powerful telescope, smaller, in orbit

7:16

around the Moon. So look

7:18

up LRO on

7:21

Wikipedia, Lunar Reconnaissance

7:23

Orbiter. And it's not

7:25

very powerful, but it is awfully close. And

7:28

it has seen the things that's behind

7:31

by the astronauts on missions, what is it, 11 to 16

7:33

or 17? They're

7:35

only six anyway. Mm-hmm, all right. Is that an

7:38

easy question? It does, and

7:40

hopefully that proves that we actually went

7:42

there. Well, it's gonna be hard for

7:44

the Moon landing deniers To

7:46

have a job, because as they keep on

7:48

landing stuff on the Moon and end up

7:51

going there, they'll say, oh, you're lying. They

7:53

Do say that the astronauts or live, the

7:55

planet Earth is, because they say that there's

7:57

only the firmant above us at 200 kilometers,

7:59

and there's... No such thing as the

8:01

sun or the moon or astronomy and

8:03

the Gps comes from join balloons of

8:05

they have hang in the is it

8:08

that until about a bit in the

8:10

satellites. That time we had a Nasa

8:12

astronaut on it ends someone said what would you say

8:14

to someone who believes the Us is flat and she

8:16

guys I sat. Planets decide

8:18

up we've got right anymore ago. He

8:21

a bright in you have a question

8:23

about black holes. The Laura: what's up.

8:25

Yesterday. Losses of good

8:28

I question concerning potholes

8:30

though when. You. Go through

8:32

the bottle. Was. Actually on the other. so

8:35

I bought. All. Got no clue,

8:37

but then it's like thirty now as well.

8:40

As all over been through a black hole

8:42

you set aside ships ruining think. I.

8:45

Love experience. I love that. What a fantastic lesson

8:47

states. they see things. This is another case of

8:49

astronomers been really bad at naming things that when

8:51

we think is a town hall we think of

8:53

something that you can go through like a hole

8:56

in a piece of paper or the whole that

8:58

you put ya meaning is leave. But a black

9:00

hole is not a whole at all. Not that

9:02

kind of whole anyway. so the idea that we

9:04

can go through it is just it's just not

9:07

something that we can do because a black hole

9:09

is actually a whole lot a mass in zero

9:11

space. Still be like saying how you gonna go

9:13

through a bowling ball. We can't. Do that of

9:15

I'd suggest you don't try that stuff we had

9:18

I try this at home and as situation but

9:20

we do have an idea of what happens when

9:22

we get too close to the whole wheat and

9:24

answer to one of the questions we can't do.

9:26

The closest black hole is quite a few hundred

9:29

light years away. I think it's guy a black

9:31

hole one with some numbers after that cause another

9:33

astronomer things so we can't do that and we've

9:35

never seen anything. Anywhere near a black

9:38

hole as far as we know anyway and

9:40

so we need a close to like all

9:42

something called spaghetti the case since happens which

9:44

is one of my favorite things where you

9:46

get pulled and stressed so much the he

9:48

gets threats, dad and step dad into spaghetti.

9:51

What wowed the Ah and a

9:54

Pr and in Austin Rosen Bridge.

9:56

Ah, now it's health and wormhole

9:58

allow he says. They were more

10:01

there's theorized way Sort of is

10:03

a. I guess it's I know is

10:05

how I thought of. Think about it, connecting to

10:07

points in space that you otherwise wouldn't be able

10:10

to connect on this he arrives. They don't think

10:12

we know if we have any proof at all

10:14

that they they truly exist is that the one

10:16

of those and problems on I suppose you could

10:18

if they existed use one to get too close

10:20

to buy call but again spaghetti the case and

10:22

is not a wave staying alive for very long

10:25

I think. also by the time you get that

10:27

close. Your also not doing so well

10:29

anyways. I wouldn't recommend. It has anything

10:31

ever been Spaghetti Five. Do we know this?

10:33

Yes we see stars get too close to

10:35

black holes all the time. So we add

10:38

another spirits a cases the right way that

10:40

we think about as astronomers we call it

10:42

accretion were black hole that that the process

10:45

is sucking things in were a black hole.

10:47

Post things on and it goes. Sort of

10:49

around the black hole. like what a going down

10:51

the drain say. That that almost exact visually can

10:53

imagine. I'm and it happens when stars get

10:55

too close a black hole aren't pulling everything

10:57

in, it's only if you get too close

10:59

to slightly been held on to the earth

11:01

right now but if we went away from

11:03

the earth and the gravity isn't pulling his

11:06

down anymore so we do see stars and

11:08

called title Disrupts in advance if you wanted

11:10

to google it. Didn't we are

11:12

visibly accidently discover the brightest of that

11:14

in the universe? A long ago we.

11:16

Did I was another? Just look at the

11:18

just wonderful space telescope results and I think

11:20

it was a black hole. A distant black

11:23

hole that was doing. this is decrease in

11:25

things. So when black holes and eat these

11:27

stars lots of interesting things happen and some

11:29

of them we don't actually know why. one

11:31

of those things it's is that these big

11:34

jets of really. Really bright light com

11:36

out of. The Black hole and to get we

11:38

don't know why this is happening. That mean the cinema

11:40

the still in a job. the goodness. But it's incredibly

11:42

bright and I think that might be. Don't quote me

11:44

on this. I think that might be what happened with

11:46

a black hole. And is a one

11:48

solar system could die yet so

11:50

it's not a hungry by calling

11:53

our one the end of the

11:55

jets Sometimes. the lives

11:57

of users are the of the size it

11:59

takes One and a half seconds to

12:01

get to the moon at the speed of light. That's as

12:03

far as we've ever got. The

12:05

nearest star is four light-years away. These

12:08

jets are sometimes 10,000 light-years

12:11

long. Now

12:13

we've got Rachel in Ailey Beach. Rachel,

12:16

you got a gift for your birthday.

12:18

What was it? Yes, it was

12:20

a picture of the stars

12:22

and it was apparently what the stars

12:24

looked like at the exact location I

12:27

was born, at the night I was

12:29

born. It was 50 years ago. So

12:31

I was wondering, is

12:33

this something that they can do and if

12:35

so, how or could it have just been

12:37

a scam for a present idea? Oh,

12:40

luckily for you, Dr. Rachel, I think this is 100% real. I

12:45

mean, I can't speak for your exact picture because of course

12:47

we'd have to check, we'd have to do the math. But

12:50

luckily we have a really good understanding of the

12:52

orbit of the earth and also the angle that

12:54

it's on and where you are. If you have

12:57

the coordinates of where you are and the time,

12:59

then yes, you can wind back that clock and

13:01

work it out. In fact, there's something called

13:03

Stellarium where you can actually put in

13:05

your coordinates on earth and it will

13:07

show you what the night sky looks

13:09

like. And you can also give it

13:11

a time. So you can also work

13:13

out when and where and see what was

13:16

above you and even what was below you

13:18

on your favourite holiday, what did the stars

13:20

look like at that date and time. So

13:22

we absolutely can. I can't say if your

13:24

particular picture is absolutely correct, but I would

13:26

say not a scam because it's a known

13:28

problem with a bit of maths. You good, Rachel? You're

13:31

good. That's amazing. Oh, cool.

13:34

That'd be a lovely anniversary present. It is, it's really

13:36

nice. What does the night sky look like on your

13:38

first date with someone? Yes, and they usually frame double

13:40

beautifully, so it is a nice one. Okay, that's gorgeous.

13:42

Now, Dr. Carl, I think we've got one which you

13:45

might be able to speak to. Peter and Victoria, let's

13:47

hope this doesn't happen, but hypothetically, you've got a

13:50

question. Hey, Dr. So

13:52

my question is, if

13:54

I was to be choking on an

13:57

ice cube, who would win?

14:00

with the ice melt first and

14:02

I'd be okay or would I choke to death?

14:05

Ah, so it turns out that we humans are the

14:08

only animal that can choke to death. Really? Because

14:10

other animals have two separate pathways that

14:12

do not cross over in the way

14:14

that ours do and the

14:17

price, the reason that we've incurred

14:19

that is that we have shifted our larynx to

14:21

a different place with evolution and

14:23

we can speak clearly and

14:25

articulate words and come

14:27

out with all sorts of different sounds. So

14:29

the price of speech is that we can

14:31

choke to death. However, there is a slight

14:34

disclaimer in that babies can suck

14:36

and talk at the same time because

14:38

the edges of their larynx have got

14:40

a little fold so they can keep

14:42

on breathing and milk can go down

14:44

and so they can suck and breathe

14:46

at the same time. In

14:49

the case of ice I had once the

14:51

terrible experience of swallowing a bit of ice

14:53

and I could feel this cold spot in

14:55

my lungs and never before and never since

14:57

have over felt this cold spot in the

14:59

middle of my chest as the ice gradually

15:01

melted. So in your case it's sort of

15:03

maybe one will win one or the other.

15:05

If it's just big enough to slide out

15:08

of the way you'd survive otherwise I would

15:10

not recommend this experiment at home. Interesting thought

15:12

experiment. How did you come up with the

15:14

idea by the way? I

15:17

was just having some ice the other day and I just

15:19

wanted to doubt it. And you went, huh? I

15:21

don't know where it happened. I'd

15:25

likely take one with a milk then.

15:28

It was a big lump of ice. It could

15:31

jam in and you could choke to death. You

15:33

only need to have, hang on. With

15:36

a choke hold you stop and never do this.

15:39

A choke hold leads to a high

15:42

incidence of strokes later on

15:44

and a choke hold will make somebody unconscious

15:46

in 15 seconds. Don't do it in martial arts. The cough shouldn't do

15:48

it. Nobody should ever do the choke

15:50

hold. It's a bad thing. So

15:53

the choke hold causes unconsciousness in 15

15:55

seconds because you're stopping the blood which

15:57

is still carrying oxygen. But if

15:59

you run out of time, air you'll still

16:01

stay alive for four minutes because your heart

16:03

is still beating and bringing oxygenated blood at

16:06

lower levels but still oxygenated to your

16:08

brain so you've got four minutes so

16:10

you've got four minutes from going unconscious

16:12

to having the ice melt and then slipping

16:14

down and then you're okay. Okay that's kind

16:16

of promising but let's hope that's

16:19

never something we need to think

16:21

about Pete. Hey Laura I wanted

16:23

to ask you when did you become

16:25

interested in astronomy and space and know

16:27

that that was a career path you

16:29

wanted to take? Well I think

16:32

those are two different questions so apparently this is

16:34

you know mum's very reliable narrators but I

16:37

went to a mini blow-up planetarium in

16:39

my local library, Lilydale library for anyone

16:41

who knows that area and

16:43

after that when I was four years old I came out and that

16:45

was just it and I remember doing

16:47

primary school projects on Pluto before while it was

16:49

still a planet and things like that but

16:52

it wasn't until I was 17 and I attended the Professor

16:55

Harry Messle International Science School at the University

16:57

of Sydney during year 11 that I saw

16:59

Professor Geraint Lewis give a talk and that

17:01

was the moment where I actually went wait

17:04

that guy he does this every day like

17:06

I could actually be an astronomer and get

17:08

paid for it. Exactly and so I sort

17:10

of knew I loved space but I

17:12

thought maybe I'd be something else like

17:15

a medical doctor or something like that who has

17:17

a telescope so someone who just you know dabbles

17:19

in space but it was that moment that

17:21

light bulb moment that I went wait you

17:23

can actually do that every day. Yeah

17:26

so the motto of the philosopher is I

17:29

think therefore I am and the

17:31

motto of the scientist is I think therefore

17:34

I get paid. Yeah yes

17:36

or in my case I program. Well there's one area that

17:38

you get asked

17:42

about a lot Vivian in Ngunnawal country what's

17:44

your question for Dr. Laura? Good

17:47

morning doctors I just

17:49

want to know if there's a scientific basis

17:51

for astrology you know you constantly hear phrases

17:54

like oh the moon was in Venus when

17:56

you were born so you're going to inherit

17:58

these sorts of traits. Is

18:00

there actually an astrophysiological basis for

18:03

it? So I get

18:05

this question a lot and it's a sort of question around like

18:07

you've asked me about astrology, lock the doors, you're about to hear

18:09

some astronomy because you know people often use

18:11

it as a bit of a gutter but then I you know

18:13

I can always make it astronomy. So

18:16

I would say as far as

18:18

the planets influencing

18:20

you affect less likely.

18:23

But some planets do. There's ideas about

18:26

whether Jupiter for example either

18:28

maybe pushes asteroids towards Earth or

18:30

deflects them away. We haven't really decided but

18:32

that's definitely a way that the planets influence

18:34

life on Earth for example and all the

18:36

orbits as well the way that the orbits

18:38

of the planets work mean that we're in

18:40

a nice stable spot. So

18:42

that is a way that the planets do affect life of

18:45

course because we need to be right here right now for

18:47

life to happen. But

18:49

astrology is based on the motion of the

18:51

stars and where they were at a particular time. So

18:54

astrology was developed during ancient Greek

18:56

times which was a few thousand years

18:58

ago and they said that your

19:00

star sign of these dates based

19:02

on when your constellation in the

19:04

sky rose and set. But

19:07

the key thing here is the Greeks did a couple

19:09

of sneaky things. They didn't

19:11

like the number 13 but there are in fact

19:13

13 constellations along the

19:15

plane that they chose for these constellations.

19:18

The 13th is called a theicus which

19:21

I'm sure there's other astronomers going Laura that's not how you

19:23

pronounce that but we're going with it. And

19:25

also things have moved on the sky since 3000

19:27

years ago. So actually if

19:30

the Greeks were going to design astrology

19:32

today those dates would be different. So

19:34

I'm not saying things have changed

19:36

but just that if they did that calculation

19:38

today things would be different in your dates

19:40

and your star sign would be different. I

19:42

would be I'm Aquarius based on the

19:45

Greek dates. But if we

19:47

calculated it today I would be a Capricorn. Oh

19:49

OK. And whenever they do

19:51

the studies just try to find it is

19:53

a relationship between your personality and the stars.

19:56

They never find a link in a standard

19:58

thing done in first year psychology. where they

20:00

hand out a paper and say, look,

20:02

we know, is Laura here? Is Isabelle here?

20:05

Is Lucy here? Okay, this is for you.

20:07

And they say, this is a profile

20:10

of you based on your birthday. Can

20:12

you tell us if it's accurate or

20:14

not? And it says things like, you're

20:16

really kind, and occasionally you don't suffer

20:18

furloughs, but overwhelmingly you're really nice, and

20:20

you're rooted to the ground solidly, but

20:23

your dreams float like a cloud. And

20:25

they say all of these things that

20:27

are vaguely complementary and contradicting each other,

20:30

and at the end they say, they

20:32

hand them in ticker with right, and

20:34

everybody's just describing exactly, and they all

20:36

got the same one. It wasn't individual

20:38

for each astrology cycle, it

20:41

was just purely the same one all the way through. And

20:44

we've done so many studies over and over. It's

20:46

nice to belong to a group though. Yeah, I

20:48

think that's what we like, is a psychological thing.

20:50

I'm not a psychologist, but it is nice to

20:53

feel like you identify with a group of people,

20:55

regardless of kind of what that group is. So

20:57

I think it is nice. Zach said, is there

20:59

peace between astrologers and astronomers? I

21:01

mean, to be honest, I don't think we interact that

21:04

much. So I don't really think that we're there particularly.

21:06

I think it depends, because I try and bring

21:08

in the astronomy really, and you know, like another

21:11

thing, that the line across the sky is called

21:13

the ecliptic, and it's the plane of the planets,

21:15

and that's where all the constellations are that they

21:17

chose. So that's, you know, fun. So I actually,

21:20

when people ask me about astrology, I'm happy because

21:22

it means I can talk more about space. I

21:24

consider any question about space to just be an

21:26

opening for you to learn something. So I'm not

21:29

really that bothered by it. Can I

21:31

ask you, is the ecliptic where the plane, the

21:33

planets will go? Is that roughly lined up with

21:35

the equator of the Sun? It's

21:37

roughly lined up with the equator of the Sun, not the

21:39

Earth, because as we know, the Earth's got a little bit

21:41

of a tilt about 21 to 24 degrees. So

21:46

it's not exactly that line. And that's why I

21:48

think that that ecliptic, that line moves, because as

21:50

the Earth goes around the Sun, our

21:52

angle means that the Sun is tilted. So

21:54

otherwise, it would be the same dates all

21:56

the time. If everything was aligned beautifully, and

21:58

we were exactly lined up, up with that

22:00

same plane of the sky there wouldn't be star

22:02

signs because all they would be at the same

22:04

place basically all the time so

22:06

that wouldn't help us so it's all about the angle. We've

22:09

got Ben in Canberra here. Dr Ben

22:11

what's your question? Morning doctors,

22:13

my question is about stars and

22:16

their visibility. Given enough time like

22:18

a hundred years, thousand years, stars

22:20

that you can't see to the

22:22

naked eye will they become visible?

22:25

This is also an excellent question and I'm sure Dr

22:27

Karl can pipe in too but I'm so

22:30

I'm going to say no based on

22:32

a couple of factors. The way the

22:34

telescopes deal with this is something called

22:36

integration time. So the longer a

22:38

telescope stares at a spot on the sky the

22:40

more light that it collects and that means if

22:43

I look at a spot on the sky for

22:45

10 minutes I might see a hundred stars but

22:47

if I stare at that spot with my telescope

22:49

for half an hour well I'll see a lot

22:52

more stars just because I am getting more and

22:54

more photons of light and so I can see

22:56

things that are fainter because I'm staring at them

22:58

for longer. But human eyes are no good at

23:00

that. We can't integrate

23:02

and catch those photons and kind of record them

23:04

so that they stack up over time so that

23:07

we can see them. And the

23:09

other thing is the universe is expanding so everything

23:11

is moving away from us excluding

23:13

the effects of gravity so it's actually more

23:15

likely that we'll see fewer stars. Following

23:18

on from that astronomers can call their

23:20

light telescopes they call them light buckets so you get

23:22

this bucket you take it out and on you fill

23:24

it up with photons. That's the first thing. The second

23:26

thing the number of stars you can see with the

23:28

naked eyes roughly a thousand and that

23:31

was worked out by Claudius Ptolemy in

23:33

Alexandria who got a bunch of mates

23:35

and they went out and lay on

23:37

ground sheet had some cocoa or something

23:39

divided the night sky up into six

23:42

sectors like the slices of a pie

23:44

and they counted about a thousand stars

23:47

so that's the number of stars that you can see

23:49

all together and will you be and there is a

23:51

star that's brightening every 80 years.

23:54

There are a few that change brightness and I

23:56

should also say there's a really amazing space telescope

23:58

my absolute favorite space telescope because I ground-based

24:00

telescope astronomer called Gaia and

24:03

it has counted 1.46 billion stars. So

24:07

that's a little bit more but the experiment of lying on

24:09

the ground and looking up, that is when you can do

24:12

it at home. We often say don't try this at home

24:14

but you could do that one at home counting stars. Do

24:16

that little rug, little cocoa. That's another

24:18

great date idea. Okay Laura, I'm through. Darian

24:23

Liz Moore, you have a question about the Tasmanian devil

24:25

but it's not the one that I'm instantly thinking of.

24:27

Talk to me, what's going on? Yeah,

24:30

hi. I was out camping in

24:33

Southwestern New South Wales. I had

24:35

a big drive to get back to where I

24:37

was going so it was 4am in the morning.

24:40

I was up and I looked

24:42

at the sky. It was complete, no moon

24:44

so it was as crisp as you

24:46

could get. In my

24:48

peripheral vision was an explosion in

24:51

the sky and it was

24:53

a long way away. It wasn't in the Earth's atmosphere.

24:55

I kept thinking about it. It was a long way

24:57

in space. I turned to

24:59

that point and the star

25:02

that was in that explosion within

25:04

two seconds just faded away and

25:06

vanished. I'm

25:08

questioning was that

25:10

a Tasmanian devil that I saw

25:13

or is it even possible to see a

25:15

Tasmanian devil with the naked eye? So

25:17

for context Laura, what is the Tasmanian devil

25:20

in the space world? So

25:22

the Tasmanian devil is not a

25:25

class of stars, it's a particular

25:27

one. The class is called luminous

25:29

fast blue optical transients. Oh

25:31

my gosh. I know. I

25:33

think we call them F-bots. Let's call them F-bots. And

25:38

this is a thing that happens and this

25:40

is another one of these fun things that we actually

25:42

don't know what's happening which is just the best. We

25:44

love that. So when a

25:46

star dies, if it's a massive star, so our sun

25:48

is not going to do this but other stars do

25:50

it, they explode. And then what's left

25:52

behind is either a black hole or something called a

25:54

neutron star. We've talked a lot about black holes already

25:57

so let's give neutron stars their time to

25:59

shine. And these are really small,

26:01

really dense stars. So they can be heavier

26:03

than the sun, but the

26:05

size of greater Melbourne. So the

26:07

sun is many times bigger than the earth, but this

26:09

is a teeny tiny star, just as heavy as

26:12

the sun. So that's a lot of mass in a

26:14

really small space. Hang on. So it's as

26:16

heavy as the sun, but it's the size of the city

26:18

of Melbourne. Yes. What?

26:20

So you're squishing a lot of stuff

26:22

into a very small space. But

26:24

these things, these S-bots, we

26:26

think that it's a big flash from

26:28

one of these kind of leftover stars

26:31

after the explosion. We're not exactly sure

26:33

how or why, but the particular type

26:35

is called a magnetar, which is a

26:37

super extra magnetic one of these. Again,

26:39

with the astronomers coming there with the

26:41

really good names, magnetar, for something that's

26:43

really magnetic. Very creative. And

26:46

the Tasmanian devil is one of these. So it's

26:48

an example of one of these things that's really

26:50

bright. Now, I'm not sure if you could see

26:52

it with a naked eye. One of the other

26:54

possibilities is maybe like an iridium flare from a

26:56

satellite or something like that. So those really

26:59

bright flashes of light. The

27:01

interesting thing here is that we're not

27:03

good, and this goes for telescopes as

27:05

well, and astronomers too. We're not good

27:07

at judging distance in space. So

27:10

most of the things that we see in space,

27:12

sort of the way that we think about it,

27:14

and even us as astronomers when we're pointing to

27:16

a particular star, is like taking a sphere and

27:18

projecting it outwards and then painting the stars on.

27:20

So we sort of talk in where it is

27:22

sort of in a longitude and latitude sort of

27:24

style, but measuring how far things are away

27:26

and judging them from on Earth is really tricky.

27:28

So there might be some other options that Dr.

27:31

Powell has too. Yeah. So Dr. Darrin,

27:33

did it move across the sky or was

27:35

it in one location? In

27:37

one location, it was like turning down

27:39

the dimmer of a light. It just

27:41

slowly disappeared in that two seconds and

27:44

it vanished completely. And what time of

27:46

night, like close after sunset or close

27:48

before sunrise or deep in the morning?

27:50

It was 4am in the morning. When

27:53

does the sun go to about 6? Yeah.

27:55

So it'd be a couple hours before that. Okay. So it

27:57

couldn't be in a ritian flag because it's not close enough.

28:00

true I think you have

28:02

a degrees or something yes

28:04

I agree something and there

28:07

are lots of things that happen in space that

28:09

it could even be something like a meteor that

28:11

might be almost coming directly towards you so a

28:13

shooting star usually goes across the sky but you

28:16

can imagine if it's sort of coming

28:18

straight towards you instead that you would see a

28:20

black glass that would fade and appear to be

28:22

in the same location on the sky but

28:24

I think I no matter what it is it sounds very

28:27

cool and also I'm very jealous of the view of the

28:29

night sky that you must have had on a dark night

28:31

I just want to take time to admire

28:34

before I jumped in my car and started

28:37

driving these beautiful sounds amazing thanks Darren

28:39

we've got Ruby in Newcastle here Dr.

28:41

Ruby what is your question hi

28:44

doctors my question is do you have any

28:46

tips on getting into the astronomy career I've

28:48

always been interested but I have no idea

28:50

where to start excellent

28:53

question so the first thing is a

28:55

Bachelor of Science and you can do

28:57

that a lot of universities and they're all fantastic

29:00

I went to Monash University as my undergrad

29:02

and that one has an astronomy kind of

29:05

minor or a major that you could do so that's

29:07

an even better choice if you've got a uni nearby

29:09

that has a lot of astronomy subjects and

29:12

then you can do an honors in Australia

29:14

or a master's and then a PhD but

29:16

some of the things that are in between

29:19

those steps are sort of the fun things

29:21

and will give you a good try and

29:23

some nice references there's things like a summer

29:25

research project so if anybody listening is maybe

29:27

a second or third year undergrad there's a lot

29:29

of places in Australia and around the world that

29:32

will offer for you to come for eight to

29:34

ten weeks over the summer and do a

29:36

real research project and often get

29:38

paid too so there's lots of little things that you can do

29:40

to try it out and see if it's the

29:42

career for you so does that mean if you're a

29:44

university that happens to be nearby which is very handy

29:46

for your first couple of years this

29:49

would be offered by somewhere somewhere else in the

29:51

world not by your university so even if you

29:53

were way out in the middle of the sticks

29:55

of the time University you could still go on

29:57

this summer project that's right so I did my undergrad

30:00

in Melbourne but I did a summer project

30:02

at the International Centre for Radio Astronomy Research

30:04

over in Western Australia and then I also

30:06

did one in the Netherlands at the Netherlands

30:08

Radio Astronomy Institute called ASTRON. So the usual

30:11

thing is to you know get all the

30:13

degrees but it's also nice

30:15

to kind of keep an eye out

30:17

for these extra opportunities to really do

30:19

research and some universities also offer say

30:22

semester-long undergraduate research projects where instead of

30:24

doing say your university does four subjects

30:26

one of those subjects is a research

30:28

project so lots of universities will give

30:30

you opportunities because research is not really the

30:32

same as studying an undergraduate degree. I don't

30:35

do exams anymore thank goodness. You

30:37

mentioned earlier as well Laura that you

30:39

are a superstar of STEM. We've had

30:41

previous superstars on the show like Tiani

30:43

from South Australia, Dr Theresa Larkening, Wollongong

30:46

and this is an initiative that really

30:48

brings female and non-binary folk

30:50

to the forefront when it comes to science

30:52

communication. What advice would you have for someone

30:54

like Ruby who maybe doesn't see themselves in

30:56

the science world that much you

30:58

know beyond the scope of I guess maybe

31:00

yeah the conversations like this? I

31:03

would suggest that everyone you know if you're driving

31:05

just take a quick glance in your rear view

31:07

mirror or have a look in the mirror and

31:09

I would say that you're looking at someone who

31:11

looks like a scientist. We often see scientists who

31:14

look a certain way you know Einstein is kind

31:16

of the typical one that students go oh yeah

31:18

that's what a scientist looks like and I often

31:20

do this exercise with primary school kids and ask

31:22

them to draw a scientist and they'll draw usually

31:24

an older white man with crazy hair in a

31:26

lab coat maybe holding a colored glass beaker of

31:29

some kind but I can tell you

31:31

that if you look like a human being

31:33

which I'm sure you do if you're listening then

31:35

you look like a scientist so I really

31:37

and I really want to also highlight that

31:40

part of science is about the

31:42

perseverance and the curiosity so sure

31:44

you know being smart is nice

31:47

but a lot of it is kind of having that curiosity

31:49

and that drive to keep going because science is a lot

31:51

you know it's not like I spend one week on a

31:53

project and then it's done it takes a long time so

31:55

that perseverance and curiosity is really

31:58

what's going to get you through there. say

32:00

everyone listening looks like a scientist to

32:02

me. Ruby thanks so much for

32:04

your question. Thank you.

32:06

We've got Dean and Frankston here.

32:08

Now Dean another hypothetical which I

32:10

hope doesn't happen but what's your

32:13

question? Hey guys my question is

32:15

what happens if you take your space

32:17

suit off while you're in the middle

32:19

of space? Carl? You will

32:21

not explode you've got a chance of surviving

32:23

as was shown in the movie 2001. So

32:26

what's going to happen is that you've got

32:30

air inside your lungs and none

32:32

outside. The surface area of your

32:34

lungs is around 70 square meters.

32:38

The air pressure inside is 10 tons per

32:40

square meter so that's 700 well 700 tons

32:42

trying to push out. So what you got to do

32:44

is open your mouth. As soon as you

32:46

go into space open your mouth and just

32:49

let all the air go and you'll probably

32:51

stay conscious for about a minute or so.

32:53

Your skin your body

32:55

will expand to some degree but skin is

32:58

made of leather and you'll probably survive. There

33:00

has been or there have been two cases

33:02

that I know of where

33:04

in altitude testing in

33:06

decompression chambers people accidentally got exposed

33:08

to virtually the vacuum of space

33:10

in a very short time and

33:13

they survived. So you

33:15

would unfortunately die after a

33:17

short period of time but

33:20

what you're counting on is that there's another space suit over

33:22

there another space you over there and you're going to jump

33:24

across the vacuum of space and they will get you pull

33:26

you inside shut the door and crank the pressure up and

33:28

you should survive. Does that make you a little bit

33:31

happier? Yeah well I was

33:34

curious if like you know you had to hold

33:36

your breath a little longer than normal or something

33:39

and no that explains it. Just let

33:41

the air out. I think I'm wrong about the

33:44

surface area for a gas exchange as opposed to the

33:46

surface area of your lungs. Call it maybe 10 maybe

33:50

5 tons for trying to explode you but skin is

33:53

made of leather. Jared

33:56

and Greensboro what's your question? Yeah,

33:58

hi doctors. I'm wondering. if you can

34:01

speed up or slow down the speed of

34:03

sound and what would happen if you did?

34:06

Ah so firstly we

34:08

get free stuff from the Sun we get energy and

34:10

it travels through the vacuum of space and

34:12

by the way when you are getting energy

34:15

through a wire in your house

34:17

say to a little electric heater

34:20

some of the energy goes through the copper wire

34:22

but a lot of it goes through the space

34:24

around it Veritasium has done a

34:26

very good video on this now sound is

34:28

different sound is just bounce bounce

34:30

bounce imagine you've got a whole bunch of people

34:33

in a line or a queue waiting

34:35

to get onto a bus or at a bank

34:37

teller or something and you push the end one

34:39

without warning and they fall onto the next one

34:42

who falls on the next one and so energy

34:44

is transferred from one person to

34:46

the other or with sound

34:48

waves from one molecule to the next

34:51

so the closer the molecules

34:53

are to each other the

34:55

higher the speed of sound so to

34:57

answer your question with air you can

34:59

speed up the speed of sound by

35:01

making it more dense so maybe

35:04

on a very cold night it's a little bit faster

35:06

and if you want to slow it down you just make it

35:09

less dense hot day does that kind

35:11

of help? yeah yeah

35:13

no that works out. Okay we've got Tom in

35:15

NAMM here now Tom you read something recently

35:18

what was it? Yeah hi

35:20

doctors um yeah so I was reading about

35:22

a giant water cloud in space that was like

35:25

40 billion times the

35:27

weight of Earth I was just

35:29

wondering how that's actually possible when water is

35:32

made of oxygen? Okay

35:34

so when the universe started there were no atoms

35:36

then about 380,000 years the energy level

35:41

cooled down the electrons could

35:43

join onto the cores the nuclei of atoms and

35:45

so we had our first atoms which were and

35:47

still are today roughly 90% of

35:50

the atoms in the universe are hydrogen and 10%

35:53

of helium and then everything else is just fairy dust like

35:56

a little bit of sprinkling. Now

35:58

a star is a machine. that turns

36:01

hydrogen into heavier elements up

36:04

to element number 26 and oxygen

36:07

sits in there. So when the first star started

36:09

firing up they started manufacturing oxygen. So then the

36:11

star comes in of its life and it throws

36:13

it out into space. It throws a significant amount

36:16

of its mass into space as they get to

36:18

the end of their life 5, 10, 20,

36:21

40 percent whatever it varies. And then you

36:23

got atoms of oxygen in space, individual

36:25

atoms which can meet up with individual

36:27

atoms of hydrogen and if you do

36:29

it in a 3 to 2 to

36:31

1 ratio H2O to hydrogen

36:33

when oxygen you end up with water.

36:36

And I think that the important thing here is everything

36:38

that we have here on earth we can find it in

36:40

space because that's where it was made. Everything

36:42

that we have here on earth was well

36:44

some of things we make ourselves I should

36:46

say we do make things ourselves but all

36:48

the atoms so that whether they meet each

36:50

other to form molecules which is a different

36:52

thing but the atoms that we have we

36:54

have in space and they usually made in

36:56

stars or at the end of a star's

36:58

life when it explodes that's how some of

37:00

the elements are made. And one of our

37:02

colleagues Tara Murphy she discovered that and the figures

37:05

are a little bit what rubbery but when

37:07

in 2018 10% of all

37:11

the astronomers were in a secret conspiracy not to

37:13

reveal this and I walked down

37:15

a corridor and they'd stopped talking and

37:18

they had the results of two neutron stars that

37:20

ran into each other. When they

37:22

ran into each other they manufactured roughly

37:24

a volume of gold roughly 10,000 times

37:26

of mass as a volume

37:29

of the earth kind of ballpark figure does that

37:31

kind of blow your mind? Mm-hmm thanks

37:34

Tom. Now if you say that they're everything we

37:36

have on earth comes from

37:38

space and is in space does that mean

37:40

Dr. Laura that aliens

37:42

exist? I'm

37:44

surprised this question didn't come up earlier. I told

37:47

you it has. Well people will text in they

37:49

always want to know. So I think aliens exist

37:51

but I don't think we'll meet them and I

37:53

don't think we'll ever have contact with them. The

37:56

universe is so big and I know humans are

37:58

pretty special and we're all individually very... special,

38:00

but we're not that special then in an

38:02

infinite universe we would be the only life.

38:04

So I do think aliens exist but the

38:06

key thing here is space is

38:09

really big, really big. So if

38:11

I wanted to talk to Proxima Centauri, that nearest star,

38:13

I would have to send a signal that would take

38:15

a couple years to get there and then wait a

38:17

couple years for it to get back and

38:20

that's only for our nearest star the rest

38:22

of the stars are very far away further

38:24

away than that. So those are your two

38:26

takeaways from science today. Space is really big

38:28

and you're not special. Dr.

38:31

Laura Dreesen, thank you so much for

38:33

joining us this morning. Seriously, I've expanded

38:35

our minds. So many great questions coming

38:37

through. If we want to read or

38:39

look at more of your work, where

38:42

should we go? So I have a

38:44

website it's astrolora.com and you can find

38:46

the links to all my socials on

38:48

there but astrolora, all one word dot

38:50

com. Thanks so much for listening

38:52

to this episode of Science with Dr.

38:54

Carl and a big thank you to

38:56

Dr. Laura Dreesen for coming through. She

38:58

mentioned that she was part of the

39:00

Superstars of STEM program and I want

39:02

to shout out two episodes we've done

39:04

with other superstars. Dr. Tiani Adamson who

39:06

is a conservation biologist and Dr. Theresa

39:08

Larkin who took us through all

39:11

the different parts of the human body. Search

39:13

the podcast feed if you want to listen

39:15

back to those episodes. Make sure you're subscribed,

39:17

liked so you can be the first to

39:19

know when a new episode drops. I'm Lucy.

39:22

This episode was produced by Sarah

39:24

Harvey and we'll catch you next

39:26

week. Bye. Dave Marchese here from

39:28

the Triple J hack team. Hey if

39:30

you love Dr. Carl's podcast like I

39:32

do you might enjoy the hack podcast

39:34

as well. Each day we bring you

39:36

the news that matters to you from

39:38

the latest science on climate change to

39:41

what's happening in politics and news around

39:43

the world. The Hack Podcast. It's your

39:45

daily fix of the news you need

39:47

to know. Get it wherever you're listening

39:49

now.