0:01

What's the furthest start that we can

0:03

see with the naked eye? To answer

0:05

this question, you have to make some

0:08

assumptions about your have been a And they could

0:10

Why can't we predict the sun's Why field?

0:12

I'm gonna say good question probably for

0:14

the last time this year. say good

0:16

question, probably for the last time

0:18

this year. and welcome to the the

0:20

supermassive podcast Astronomical Society with me

0:22

with me science journalist Isie astrophysicist Dr.

0:24

Becky Dr. Becky Smetherst. Now the Eagle-eyed or among

0:26

you you notice that our

0:28

last podcast of of 2024 is not an

0:30

not an episode about the

0:32

scientific search for extraterrestrial life

0:34

we we promised. A slight change slight

0:37

change of plan. We weren't

0:39

quite ready for that one.

0:41

it it turns out getting, you

0:43

know, someone who studies, like,

0:45

the search for alien you know...

0:47

I trying to the - universe down

0:49

in December down in December trying to

0:51

find the aliens themselves. to find the aliens

0:53

themselves. just swap things around things around.

0:55

So we're going to tackle some

0:57

of your brilliant questions for

0:59

this episode and obviously we can't

1:01

have an episode without without Dr. Robert

1:03

the Deputy Director of the

1:05

Royal Astronomical Society. Astronomical going to

1:07

kick things off with an easy

1:09

question for the both of

1:11

you. for you have a you festive

1:13

astronomy fact? fact? Well, I don't have

1:16

a huge I don't have a huge number,

1:18

but I think there is a sort

1:20

of night sky object, which which is the genuinely

1:22

named named Christmas of cluster which has of NGC

1:24

as well. It just which has got a to

1:26

as well. It just happens to be

1:28

visible right now as in the Monoceros, the

1:30

the unicorn to the east of the So if of in

1:32

So if you're in the North event,

1:35

looking to the left of it. And

1:37

it just so happens that infrared images, some

1:39

telescopes of this Christmas tree cluster tree

1:41

to be coded to show it in

1:43

green. to show to why they do that. in

1:45

their why they would do it's a really lovely object and it

1:47

does look a little bit like the lights of

1:49

a Christmas tree. does look a little bit make

1:51

lights of a Christmas tree. Yeah, why don't

1:54

they make that false color in this show?

1:56

It's impossible to guess, I think. Yeah, my

1:58

fact for this week, week. come

2:00

on the No Such Things a Fish

2:02

podcast. This is great. My fact for

2:04

this week was in 2017 undergraduate students

2:06

at the University of Leicester calculated the

2:08

number of Christmas lights you would need

2:10

to add to the outside of your

2:12

house to make it visible from space.

2:14

Amazing. Yeah, I'm like I want to

2:16

find these students and I want to

2:18

shake their hands because this is fantastic.

2:20

So it turns out if you're interested

2:22

you would need 10,060. lumens, so it's

2:24

the like, you know, magnitude of lights

2:26

you would need, or the equivalent of

2:28

2,638 LED. Christmas lights. Oh my gosh,

2:30

I know. It's wonderful. They were inspired

2:32

by the Christmas film from 2006, they

2:34

decked the halls for those who've seen

2:36

it, because I think that's the whole

2:38

premise of the film and they were

2:40

like, well, let's visit this. We could

2:42

do this. Yeah. Also, speaking of Christmas

2:44

films, easy, did you? Did you? Have

2:47

you seen the new Netflix Christmas films?

2:49

Well, with Lindsay Lohan, it's called Our

2:51

Little Secret? And the premise of the

2:53

film is like, like, like, something happened.

2:55

in 2014 and they have to zoom

2:57

through to 2024 and the opening credits

2:59

of the scene is then basically going

3:01

through like you know a load of

3:03

like world events to show time passing

3:05

and three astronomy news stories made it

3:07

in there and they were the only

3:09

science things that were shown in that

3:11

global sort of news recap from 2014

3:13

to 2024 in an episode. Yeah it

3:15

was Pluto's so the New Horizons fly-by

3:17

of Pluto with that first image of

3:19

Pluto we got was perseverance landing on

3:21

Mars and then the first ever image

3:23

of a black hole in Messier 87.

3:25

There was also William Shatner going to

3:27

space which I guess you could also

3:29

count but I didn't. obviously the era's

3:31

tour from Taylor Swift at the end

3:33

of it. But I figured that one

3:35

of the projection team on the film

3:37

must have been a big astronomy fan,

3:39

you know, maybe they're listening now, who

3:41

knows? Amazing, I mean that's just maybe

3:43

even more excited to watch this, Lizzie,

3:45

Christmas, I'm too honest. Actually, I'm gonna

3:47

throw something in here as well, because

3:49

I was looking at Christmas on the

3:52

ISS, and then I got into a

3:54

bit of. rabbit hole so my fact

3:56

that I want to bring to the

3:58

table is in 1973 on board the

4:00

Skylab orbital station astronauts Gerald Carr William

4:02

Polk and Edward Gibson made their own

4:04

Christmas tree they used discarded food cans

4:06

and sort of pushed them all together

4:08

to create a stem and then like

4:10

various branches of the tree and then

4:12

use little stickers as decorations and put

4:14

a cardboard cut out of a comet

4:16

on top. that once they were back

4:18

to earth, they were like, yeah, your

4:20

Christmas tree is nice, but it's not

4:22

as good as the one we made,

4:24

but in space. Exactly, exactly. Nothing ever

4:26

compares to it, ever. Yeah, totally. Okay,

4:28

so let's get on to the listener

4:30

questions. And Robert, Matt P. 24601, wants

4:32

to know which star or planet do

4:34

you think was most likely to have

4:36

been the star of Bethlehem? Well, Matt,

4:38

Matt P. 24601, definitely a perennial question

4:40

there, one that funny enough. of every

4:42

year at this time of year. I

4:44

think the answer is, you know, something

4:46

we'll never know for sure. And as

4:48

an atheist, I'm probably going to get

4:50

into at least warm water over this.

4:52

I'm treading carefully. But on the other

4:55

hand, I'd be genuinely interested in astronomical

4:57

phenomena that coincide with the suggested date

4:59

or dates, actually, of the birth of

5:01

Jesus. Now, there's actually a nice piece

5:03

on the Vatican Observatory website, which is

5:05

a respectable. but it's just on astronomical

5:07

institution actually and it invites us to

5:09

use our sense of wonder over what

5:11

it might have been and I think

5:13

that's absolutely fine. Yeah, it's a totally

5:15

reasonable way of looking at it and

5:17

happy Christmas to the astronomers in the

5:19

Holy Zay. But turning to the suggested

5:21

ideas, so it ranges from it didn't

5:23

exist at all to all manner of

5:25

things and it could have been invented

5:27

as this so-called pious fiction or midrash

5:29

where the star was added in to

5:31

emphasize Jesus's divine nature. And in astronomy

5:33

though, there are quite a few obviously

5:35

significant things in the sky that could

5:37

be candidates. And for example, there was

5:39

a really incredibly close conjunction of Jupiter

5:41

and Saturn in 7BCE, or an even

5:43

ridiculously close. conjunction in Jupiter and Venus

5:45

in 2 BC where the two worlds

5:47

would actually have a pitch pit of

5:49

merge that's very very rare indeed so

5:51

I imagine if you were looking at

5:53

that in the sky thinking the astrological

5:55

significance run the astronomical significance you know

5:58

if you're thinking about the mythology associated

6:00

with that you would have thought wow

6:02

or something something very unusually is happening

6:04

here and that came after Jupiter and

6:06

Venus were close together a year earlier

6:08

and they were also near the star

6:10

regular the bright star regular in Leo

6:12

as well. Another idea is a comet,

6:14

although there don't seem to be records

6:16

and the Chinese are really really good

6:18

at keeping those records at the time,

6:20

of anything that bright in that period

6:22

of time, there's possibly one in five

6:24

BCE, you know, just again really quite

6:26

uncertain what it might have been like.

6:28

And there could also have been a

6:30

supernova, although... you know, again, he sort

6:32

of imagined somehow that would have had

6:34

more of an impact in historical text.

6:36

But anyway, there could have been one

6:38

in the 4 BC that happened to

6:40

create the system with the unromantic name

6:42

PSR 1913 plus 16, which happens to

6:44

be the first binary pulsar discovered. So,

6:46

but all these things, my personal hinges,

6:48

either the star never existed at all,

6:50

or it's probably, you know, the Jupiter

6:52

Venus conjunction seems to me like a

6:54

good explanation, because the idea of which

6:56

I don't think... anything like that happened

6:58

in the 20th century, it certainly hasn't

7:01

happened yet in the 21st century, the

7:03

idea that two planets are so close

7:05

together that they're actually touching is extraordinarily

7:07

rare. So maybe that was so significant

7:09

that people drew on that. Yeah, there

7:11

was a Jupiter Venus conjunction. Was it

7:13

like a few Christmases ago now, like

7:15

two, three Christmases ago? And I remember

7:17

that was really nice to see that

7:19

they were coming so close together and

7:21

they were so bright. But I mean,

7:23

they came still like a thumb width

7:25

apart or something. I can't even imagine

7:27

what it would look like if they

7:29

overlapped completely from our perspective here on

7:31

earth. Absolutely. And even the Jupiter Saturn

7:33

one that we all got very excited

7:35

about that. you know they were very

7:37

close they were well under you know

7:39

somewhat of a fairly small fraction of

7:41

a degree but they were still not

7:43

touching and it must be so extraordinarily

7:45

rare. that happens. I want to look

7:47

now when the next time that's going

7:49

to happen, like is it going to

7:51

happen in our lifetime? We'll get back

7:53

to you in the future. I have

7:55

a feeling from memory not but we

7:57

can check. So not my lifetime at

7:59

least. Well at least now we'll have

8:01

an answer when someone asks like if

8:04

you could go in the future if

8:06

you could go anywhere to see the

8:08

web and I'll go to the next

8:10

conjunction. Okay well we'll stick on the

8:12

theme of spotting things in the night

8:14

sky because Robert there's a question What

8:16

a brilliant name can we just say?

8:18

And their question is, what's the furthest

8:20

star that we can see with the

8:22

naked eye? Yeah, I mean, perring Posa,

8:24

a great name, great question. Well, I

8:26

started, funnily enough with the Google search,

8:28

because it's not the sort of thing

8:30

Astronomers. collate in papers and part of

8:32

the reason is you know it depends

8:34

how good your eyes are and circumstances

8:36

to what the faintest thing you can

8:38

see with the naked mind. Mine is

8:40

not very good. Yeah yeah see but

8:42

you can probably see the Andromeda galaxy

8:44

right two and a half million light

8:46

years away so on you know for

8:48

non-stars for big things it's a really

8:50

long way. But, so when I looked

8:52

around, there were several articles saying, oh,

8:54

this is variable style v762 Cassiope, which

8:56

means it's in the constellation Cassiopea, 16,000

8:58

light years away, but then you dig

9:00

around quickly and the Wikipedia article said,

9:02

oh, actually it's 2,500 light years. So

9:04

I went into the Simbag database, which

9:06

has things like parallax. looking at how

9:09

it shifts back and forth as the

9:11

earth goes around the sun, measured by

9:13

the Gai satellite, and indeed that comes

9:15

up with two and a half thousand

9:17

light years, so a lot closer. You

9:19

can get these numbers for yourself if

9:21

you good luck remembering this, but if

9:23

you put HD 7389 into that Simbad

9:25

database, you get those numbers and then

9:27

there are calculations to help you work

9:29

it out. So then I was looking

9:31

around a bit more and there isn't...

9:33

I don't think there's any definitive answer

9:35

to this yet at least. Somebody needs,

9:37

probably it needs to be some sort

9:39

of, you know, post-op with time on

9:41

their hands. I think, well, Jackie doesn't

9:43

really have time on their hands, but

9:45

you know, yeah, exactly. But, and that's

9:47

because the stars get fainter, we see

9:49

a lot more of them, so unless

9:51

something is very luminous or very notable,

9:53

you know, we can just about see

9:55

if they're naked. we might not have

9:57

a record of it. Two examples are

9:59

stars in Cepheus, which happens to be

10:01

visible at this time of year quite

10:03

well, and one of them is Mucefi,

10:05

famous as an incredibly red Garnet star,

10:07

and it might be about 3,000 light

10:09

years away, but it's actually quite hard

10:12

to tell the measurements are not that

10:14

good. as it happens that one is

10:16

also so large that you know even

10:18

without uncertainty it would fill the solar

10:20

system as far out as Jupiter absolutely

10:22

enormous colossal star the other one called

10:24

New Cephi and that's a white blue

10:26

super giant that might be as far

10:28

away as 4,700 light years you know

10:30

with again with a lot of uncertainty

10:32

but you know both of those are

10:34

actually comfortably a lot brighter than the

10:36

naked eye limit of a... about magnitude

10:38

6.5 and even the fainter one is

10:40

about seven and a half times brighter

10:42

so somebody really needs to go out

10:44

there and trawl through the catalogs right

10:46

some crawler software or something to try

10:48

and work this out. And the one

10:50

thing I'd add is if you get

10:52

a supernova then they're obviously visible over

10:54

much greater distances and exploding star is

10:56

really very bright indeed. The one in

10:58

1987 which I remember but didn't see

11:00

down in the large Magellanic cloud, seen

11:02

for months in the southern hemisphere and

11:04

that was 170,000 light years away. So

11:06

supernova, single star, really are so bright,

11:08

you see them a long long way

11:10

off, but nothing like that around the

11:12

moment. I really hope I get to

11:15

see one in my lifetime. That is

11:17

just like a fingers cross, 2025, amazing,

11:19

but lifetime. Yeah, that'll be great. Since

11:21

we have one in our galaxy, four

11:23

centuries. So we are overdue. Yeah. Oh,

11:25

and Becky in true Q&A style. We

11:27

have a question for you about black

11:29

holes and I think we've got quite

11:31

a few on the way to this.

11:33

I've been disappointed if we didn't come

11:35

through it. And do you know one

11:37

wants to hear about black holes this

11:39

episode? Kelsbury's. No. So Joe has a

11:41

question about planet X, which is also

11:43

known as the solar systems planet 9.

11:45

We did an episode about this back

11:47

in May 2021 2021. do go and

11:49

have a listen back to that. I

11:51

thought that was more recent than that,

11:53

but time is doing its thing. Anyway,

11:55

Joe says, I have a question about

11:57

the possibility that Yeah Joe, this is...

11:59

the dream, right? So if the solar

12:01

system did have this baby black hole

12:03

just hanging around, you know, and if

12:05

you work out the maths from sort

12:07

of like, okay, the reason we think

12:09

this black hole might be the edge

12:11

of the solar system is because, you

12:13

know, there's all these dwarf planets at

12:15

the edge of the solar system, sort

12:18

of like, like, asteroid-style things, and their

12:20

orbits are being affected by something, and

12:22

we don't know why, and we can't

12:24

explain it, and people have like, like,

12:26

like, like, like, like, 400 to 800

12:28

A-U distance. So an A-U is the

12:30

distance from Earth to the sun. So

12:32

400 to 800 times more distant than

12:34

the Earth is from the sun. That's

12:36

like 10 to 20 times the distance

12:38

of Pluto from the sun to give

12:40

you an idea. The voyage probes, which

12:42

launched at the end of the 70s,

12:44

are not that far out yet. There's

12:46

some figure out while you're around 115

12:48

70-ish, something like that A-U. So we

12:50

would definitely need to send something quicker.

12:52

Well, we said voyage of probes. Big

12:54

problem there, though, is slowing something down

12:56

once it's that far out so that

12:58

you could actually maybe like orbit this

13:00

little baby black hole from, you know,

13:02

a safe enough distance for the probe,

13:04

for example. Otherwise, essentially, you're just going

13:06

to each something straight past it. which,

13:08

you know, is not what you want.

13:10

This is why we haven't put a

13:12

probe in orbit around Neptune or Uranus,

13:14

or even Pluto, right? The New Horizons

13:16

probate did a flyby of Pluto. Voyager

13:18

did, the Voyager probes did flybyes of

13:21

Uranus and Neptune. Because it's very hard

13:23

to slow down. And people have sort

13:25

of talked about this idea of... atmospheric

13:27

breaking, almost kind of like skimming a

13:29

stone off the surface of the pond,

13:31

right? It's kind of like what you

13:33

do to your probe. You just skim

13:35

into the top of your in a

13:37

sun atune atmosphere to slow it down.

13:39

No look there though with a black

13:41

hole. So assuming we can solve that

13:43

problem, then yes, we would totally send

13:45

a probe to orbit around this black

13:47

hole if it was there on the

13:49

edge of the solar system. Of course

13:51

we send a camera, I think it

13:53

would be stupid if we didn't. It's

13:55

not like they're overly expensive, right? It's

13:57

not the most expensive part of sending

13:59

a probe is the camera these days.

14:01

And I think, if you're thinking, would

14:03

we really even see anything? Like, yes,

14:05

I think we would. We would definitely

14:07

see the black calls impact on the

14:09

light from stuff behind it, for example.

14:11

So as it passed in front of,

14:13

you know, stars in the Milky Way,

14:15

for example, we would basically have this

14:17

sort of this sort of perfect. gravitational

14:19

lens telescope, right? It's the light room

14:21

stars behind it, got sort of bent

14:23

by the gravity of the black hole.

14:26

In terms of other things you'd send

14:28

though, like one thing we want to

14:30

test for is gamma rays, because if

14:32

this, so it's a black hole that's

14:34

thought to be a primordial black hole,

14:36

someone that was forming in the very

14:38

early days of the universe, like, you

14:40

know, 13.8 billion years ago, let's say.

14:42

And so because it's been around for

14:44

that long, it... sort of would have

14:46

collected like a little halo of matter

14:48

over the years. Like it's just sort

14:50

of wandering through the solar system and

14:52

empty space like you know it is

14:54

the vacuum space but it's not quite

14:56

empty it's like one particle every huge

14:58

volume right it would have slowly sort

15:00

of gathered those things like close to

15:02

it and around it. So it would

15:04

have gathered matter, but it also would

15:06

have gathered like antimatter, right? And antimatter

15:08

and matter when they collide and meet,

15:10

they annihilate and produce gamma rays. So

15:12

you might expect if there's quite a

15:14

bit of a halo of stuff around

15:16

that black hole from over the years,

15:18

it might annihilate and we might see

15:20

those annihilations going on, which would be

15:22

really cool to see as well. And

15:24

finally the spigetification question. I think we'd

15:26

be stupid if we didn't send something

15:29

into water back off. Like if we've

15:31

got a probe orbiting it from a

15:33

safe distance and then we just send,

15:35

you know, like a little cube set

15:37

or something. almost do like

15:39

the the test where

15:41

it's like okay

15:43

you've got got an Alice who's

15:45

observing Bob fall into a black hole

15:47

and they'd be called be

15:49

called Alice and Bob

15:51

it it would be

15:53

the most most physics

15:55

ever right you sent

15:57

this little cube set

15:59

that would probably

16:01

have a camera on

16:03

board as well board

16:05

as also probably send

16:07

out some sort

16:09

of beep of a

16:11

signal that we would

16:13

probably be able

16:15

to see to of

16:17

have that time dilation

16:19

to it where

16:21

we would where we that

16:24

that. beep was going off every minute gets

16:26

slower and slower because of the gravitational effects because of

16:28

the black hole and things like that. We

16:30

could almost directly test it. got closer right, you think,

16:32

well, at some point it's gonna get like around

16:34

a black hole like that. But, you know, it's

16:37

like sending probes into atmosphere, well,

16:39

right? it's at some point it's going to get lyric

16:41

acid, right? We still did it, a

16:43

you know? I think like that. to

16:45

the extreme. like I was just

16:47

like, we're sending something to break

16:49

it. Yes. right? Yeah. Just a good way.

16:51

In a great way for some weird

16:53

always say learn something more if it breaks you

16:55

go to fix it. to fix it. Well,

16:57

there we go. Joe, I hope that

16:59

answered your question. that And we have

17:01

this question from Matt in Australia. question

17:04

from Becky Izzy, Robert Becky, Izy, Robert, and producer

17:06

that Richard always appreciates that always So

17:08

there we go. the Christmas, Richard.

17:10

go. Merry Christmas Richard. Maybe this is it. In

17:12

the last bonus last bonus episode,

17:14

19 had a had a question

17:16

about accelerating particles with

17:18

mass to the speed of

17:20

light. So I thought

17:22

I'd throw a wrinkle at

17:24

Dr a wrinkle at you accelerated

17:26

an uncompressed an potato to

17:28

99 % the speed of

17:31

light, would that potato

17:33

become a black hole due

17:35

to Einstein's mass hole due to

17:37

Einstein's mass energy equivalents?

17:39

this question. so much Matt and it was

17:41

much was like was undergraduate undergraduate

17:43

maths question a with a

17:45

puzzle in the morning

17:47

newspaper, like all in one. damned I was

17:49

in heaven, honestly. right so let's

17:51

go through this go through this.

17:54

not aware for those not aware, first

17:56

of all, let's do a little Einstein's

17:58

generalativity 101 as you excel objects close

18:00

to the speed of light, the more

18:02

energy you put in, it doesn't go

18:05

into increasing an object speed, but instead

18:07

increases the objects mass, at least when

18:09

you get close to the speed of

18:12

light. So that's what we were talking

18:14

about in last month's bonus episode. So,

18:16

as for our potato. Sadly, no, the

18:19

potato would not become a black hole

18:21

at 99% of the speed of light.

18:23

So essentially, the equation for this is

18:26

quite simple. You have the mass of

18:28

the potato originally, and it gets timed

18:30

by this thing called the gamma factor

18:33

to give you the relativistic mass, right?

18:35

So, the gamma factor is one over

18:37

the square root of one minus the

18:40

speed over the speed of light all

18:42

squared. Okay? So, if our speed is...

18:44

0.99 times the speed of light, 99%

18:47

of the speed of light, then our

18:49

gamma factor is about seven-ish. So our

18:51

potato only increases by mass about seven

18:54

times and that's not heavy enough to

18:56

become a black hole. Like potatoes aren't

18:58

that heavy in the first place. I

19:01

don't know if you've noticed. I've seen

19:03

lumps of metal that are seven times

19:05

in the other than a potato. So,

19:08

so... You might ask, is he and

19:10

Matt, and Robert, since everyone's here, how

19:12

fast does a potato need to be

19:15

travelling to become so heavy? Well, yeah.

19:17

It becomes a black hole. It's on

19:19

my mind for Christmas. Yeah, you know,

19:22

I just can't fall asleep thinking of

19:24

all the presents I've got a wrap

19:26

and how big a potato and need

19:29

to move. Okay, seriously. To answer this

19:31

question, you have to make some assumptions

19:33

about your potato. Okay, so Matt said

19:36

a medium-sized potato. So, you know, not

19:38

a new potato, not a baked potato,

19:40

a medium-sized potato. I've got loads of

19:42

those in my cupboard, ready for roasted

19:45

on Christmas Day. Is it a flowery

19:47

or waxy? It's a Maris Piper, I

19:49

don't know. Flowery, flowery. Anyway, so I

19:52

grabbed a few, I had a little

19:54

measure. I basically decided on some round

19:56

numbers in the end because I was

19:59

like well let's say roughly it's about

20:01

a 10 centimetre wide potato let's assume

20:03

it's this fear because I'm a physicist

20:06

and that's what we do and let's

20:08

assume it's around about 100 grams for

20:10

those saying at home I should have

20:13

done it properly and taken a specific

20:15

potato and I should have got the

20:17

numbers right you will very quickly see

20:20

the numbers don't matter so we are

20:22

going to go with a 10 centimetre

20:24

potato that's about 100 grams so Because

20:27

we know that black holes collapse when

20:29

you squish an object into a volume

20:31

that's less than it's what's called it

20:34

swatch shield radius, right? So that's essentially

20:36

like the radius of which you'd have

20:38

to be traveling fast in the speed

20:41

of light to escape it, right? So

20:43

we need to work out the mass

20:45

of a 10 centimetre, diameter, potato. So

20:48

that's a swatch shield radius of 5

20:50

centimetres. Which if you do the mass

20:52

is 30 trillion kilograms. It's about 5.6

20:55

times the mass of Earth. Or instead

20:57

of you remember our gamma factor before

20:59

being 7-ish, it would be 300 trillion

21:02

trillion potatoes, so a gamma factor of

21:04

300 trillion trillion trillion. Which unfortunately it

21:06

actually makes the math very very difficult

21:09

because if you try to get back

21:11

from your gamma factor to what the

21:13

velocity would be, remember I said gamma

21:15

was like one over the square root

21:18

of one minus the velocity over the

21:20

speed of light or squared. To get

21:22

back to it you need to do

21:25

like one over gamma squared, which if

21:27

you've got a gamma factor of 300

21:29

trillion trillion, if you square that number

21:32

and then do one over that massive

21:34

massive number, most calculators are going to

21:36

be like, you've got zero, if you're

21:39

going to do one minus zero, you've

21:41

got one. So I managed to hack

21:43

this with Python code, thankfully, that lets

21:46

you go out to a ridiculous number

21:48

of decimals to get you an accurate

21:50

answer. Well, that's potato. And it is

21:53

99.9.9. 52.9s. percent of

21:55

the speed of light.

21:57

Is the speed

22:00

a medium -sized potato

22:02

would have to be

22:04

traveling at two?

22:07

collapse into a black hole. And

22:09

there you go, That's Christmas of. I

22:11

mean, who knew that that's where it would

22:13

lead us? Matt in Australia, thank you

22:15

so much. Honestly, Matt had an absolute joy

22:17

answering that question and that's all I'm

22:19

going be able to think about Christmas Day

22:21

making my roasties. We know what you're

22:23

going be talking about around the dinner table.

22:25

Did you know? OK,

22:28

Robert, Jane Payne

22:30

on Instagram asks, What

22:32

do we need a moment to regroup?

22:34

We probably do. I'm just thinking whether it

22:36

applies to sprouts or what size of

22:38

turkey would be. kind kind like of a had

22:41

a sized sprout. Exactly. Big or a

22:43

small turkey, geese, you know, nuts, things, nut

22:45

you you know. Oh,

22:47

brilliant. Okay, Robert, Robert

22:49

J. Payne on Instagram

22:52

has a question and they ask. Is

22:54

there a certain criteria for a

22:56

planet or moon to become tidally

22:58

locked? Yeah. Well,

23:00

I'm going to say good question, probably for the

23:02

last time this year. Yeah,

23:04

the answer is yes. But first of

23:06

all, should say what it is. So tidal

23:08

locking is or captured rotation is where the

23:11

rotation period of a body or how long

23:13

it takes to spin on its axis matches

23:15

its revolution period or how long it takes

23:17

to complete an orbit around its parent

23:19

body. So the example being the moon and

23:21

the earth the classic one, because the moon

23:23

more or less keeps the same face to

23:25

us. And we see a bit more than

23:27

half of it because if you're further north.

23:29

or or depending on where you're looking

23:31

at moon rise or moon set or

23:33

the fact the moon's orbit is an ellipse

23:36

you get to see a bit round

23:38

the back but there are still two -fifths

23:40

of the moon we never see from Earth

23:42

for this reason because its face is

23:44

locked towards us. Now it happens because you

23:46

get energy dissipated through tidal heating the

23:48

object and stretching and so on and that

23:50

eventually eventually over a long time scale

23:52

typically billions of years it depends on the

23:54

system means that the rotation that object

23:56

slows down until it locks into place and

23:58

that happens to both of them actually so you

24:00

know it will happen to the earth as

24:02

well in about about billion years time which

24:04

is much much longer than the than of the

24:07

of the sun the earth moon would do the same thing

24:09

and the thing the the both be moon would both

24:11

each other locked with each other to give you a

24:13

kind of number for when it happens is

24:15

quite hard what it depends on what the

24:17

objects made rigid it is. What you on how rigid

24:19

it is you know, you can it, is that

24:21

more massive will happen, the quicker it will happen, and closer the quicker

24:23

it will happen it, the closer the quicker it the

24:25

quicker and the closer well, and it's very strongly

24:28

dependent on that it goes to the power

24:30

going to, when it is going to, when it going to, when it is know

24:32

if it's it is going to, when is going to

24:34

rapidly it's going to, think it's going the it's system that

24:36

might have happened going quickly as well because we

24:38

think the moon was much it's closer to

24:40

the to, when it formed when it's in this big

24:42

collision between the proto the and a mars sized

24:44

body a the debris forming the moon debris know

24:46

it may have been that the moon locked

24:49

into place quite quickly as a result moon

24:51

really hard to say exactly how long though as

24:53

a if you sat around if you had

24:55

an infinite amount of time then in theory

24:57

all if you eventually end up like this it's

24:59

just time, then in theory, all very long time if

25:01

they're further apart and if the body

25:03

is less rigid and all of those

25:05

things very, very no easy answer but the

25:07

criteria is just really that they're in

25:09

orbit around each other and this process is

25:11

going to happen if you sit around

25:13

long enough long you know that could

25:15

be know that could guess hundreds or even billions

25:17

or even trillions of years in of

25:19

cases. We do by the way also

25:21

see it with lots of satellite planet

25:23

systems in the solar system and famously

25:25

Pluto and and its biggest moon Sharana already mutually locked they

25:27

keep the same face to each other.

25:30

there all the time as they orbit round. And you

25:32

know we see it with other know we see it with

25:34

other moons in the solar system I think

25:36

it's about them of them doing that particularly big

25:38

moons of and Saturn and Saturn. also with planets going

25:40

going stars as well because if you get

25:42

say a planet say, a a very near to star

25:44

then it's locked in place in the same

25:46

way way. So I'm not not giving you a very

25:48

precise answer but the criteria are essentially you

25:50

know pretty much everything will do if you've

25:52

got enough time to wait to wait. know what you

25:54

should have done, Robert? should have worked out how long it would have

25:56

took to a medium how long it would have took a

25:59

medium-sized potential. It probably is the more than

26:01

the lifetime of the years, but yeah, right now

26:03

that is another, that is another Christmas dinner question,

26:05

is it? Or a sprout. Well, we should do

26:07

with a sprout this time. Yeah, it's no sprout.

26:10

Yeah, it would make more sense. I

26:13

want to take a moment to break from

26:15

the questions and reflect on the year in

26:17

space. So for the JOV, what have been

26:19

some of your favorite astronomy moments of 2024?

26:21

Well, mine's from the very start of the

26:23

year. I'm still not over it. And that

26:25

is that Neptune is not as blue as

26:27

we all collectively thought it was. Do you

26:29

remember this story? So wild. Yeah, so this

26:31

was, we met there was one in Oxford

26:33

actually, it was by Irwin and collaborators. And

26:35

the thing that makes me laugh about this

26:37

is that they started wanting to study Uranus

26:39

and then they were like, oh, this thing

26:41

about Neptune, and we're like, oh no. But

26:43

yeah, they were trying essentially to work out

26:46

sort of with the seasons on Uranus as

26:48

it orbits the sun. How does that the

26:50

color of Uranus change? And so to do

26:52

that, you need obviously like observations of Uranus

26:54

over the past like, you know, as many

26:56

decades as you can get your hands on

26:58

from the ground. But then essentially you need

27:00

to calibrate all of that data from the

27:02

ground with the voyage of probes fly by

27:04

of Uranus that actually took like true color

27:06

images, like true color images from. from Voyager

27:08

and they were like, oh okay, well we

27:10

should probably reprocess them ourselves again. And they

27:12

were like, wow we're here, we're doing Uranus,

27:14

should we do Neptune as well? We grabbed

27:16

the Voyager images and they did it and

27:18

they realized, oh. the true color of Neptune

27:20

isn't like the blue image that we you

27:22

know is like the image that you know

27:24

that you always show for Neptune and they

27:27

realize that NASA like very clearly communicated like

27:29

in the press conference from the voyage of

27:31

probes back at the end of the 80s

27:33

like oh hey we fiddled with the sort

27:35

of levels here and the saturation just to

27:37

show you the features in Neptune's atmosphere that

27:39

like Uranus is super smooth and Neptune has

27:41

all these features but and you can only

27:43

see them if we like with the levels.

27:45

And they released that image to be like,

27:47

hey look, you can see the features. And

27:49

people were like, great, that's Neptune. Yeah. And

27:51

like amazing blue color. And instead, like if

27:53

you actually make like a true color image

27:55

of Neptune, yeah, you don't see the features

27:57

as much because the color difference, you know,

27:59

isn't quite as apparent. But actually the color

28:01

looks more like what we're used to seeing

28:03

for Uranus. That's what hazy pale blue rather

28:06

than that sort of dark royal blue. But

28:08

that's Neptune's identity. Yeah, I know. I have

28:10

to reprogram my brain. Except that, no. That's

28:12

why it's, you know, it's, it's still, it's

28:14

like I'm in 11 months that I'm still

28:16

thinking about it. And Robert, how about you?

28:18

Well, hopefully not not. quite such a, you

28:20

know, traumatic also. No, I think, look, I

28:22

mean, this year, wow, we had two, just

28:24

two displays, the Northern Lights. Honestly, when does

28:26

that happen if you live in the South

28:28

of England? This is absolutely unprecedented. And we

28:30

had a bright comet as well, so, you

28:32

know, really brilliant, actually. It just shows what

28:34

I knew and my powers of prediction were

28:36

completely useless. Again. But wasn't there a clip

28:38

in the US though this year? I wanted

28:40

to be like... I wanted to be like...

28:42

I wanted to taste a trick from it.

28:44

Yes, because that was going to be one

28:47

of my highlights. That was going to be

28:49

one of my highlights. It was just like

28:51

honourable mention to you. Yeah, it's fair. I

28:53

know. I'm just resenting my colleagues across the

28:55

Atlantic who had that too. And the aurora

28:57

and the comet. But I loved... I also,

28:59

but not a discovery, but I did not

29:01

a discovery, but I did love the Jedi,

29:03

but I did, but I did, but I

29:05

did, but I did, but I did, I

29:07

did, I did, I did, I did, I

29:09

did, I did, I did, I did, I

29:11

did, I did, I did, I did, I

29:13

did, I did, I did, I did, I

29:15

did, I did, I did, I did, I

29:17

did, I did, I did, I did, I

29:19

did, I did, I It's taking a really

29:21

really powerful telescope and pointing it at something

29:23

familiar is great. It's always just fun as

29:26

well. Did you see the recent released a

29:28

sombrero image as well? I did. The sombrero

29:30

galaxy, sorry. Yeah, no, I'm a sombrero. I

29:32

can imagine hanging it in front of the

29:34

top. But that one was wonderful for

29:36

was wonderful for me

29:38

to see, because I

29:40

studied galaxies they're stuff. So

29:42

it was really cool

29:44

to see the differences

29:46

between the Hubble image

29:48

that you get, which

29:50

is just looking at

29:52

the the Hubble and then

29:54

the that image that

29:56

they released just at the

29:58

at the star light, and then that

30:00

was giving off by

30:02

dust that was glowing,

30:04

and it's a completely

30:07

different shape. Like, it's

30:09

completely lost that, like,

30:11

that shape that the

30:13

Hubble image dust famously has.

30:15

light So image that really

30:17

nice to see that,

30:19

you know, the dust

30:21

is doing very different

30:23

things to the stars,

30:25

which was quite cool. Yeah,

30:27

Yeah, very cool. back onto the back onto

30:29

the questions. a great we've had

30:31

a great question here from Instagram, Instagram,

30:34

the which is, do with an are there

30:36

jobs you can do with an

30:38

astrophysics degree outside of academia? to go

30:40

to both of you, think I'll to go to

30:42

both of you else to add. Yeah, if I

30:44

have anything else to add. this first. I mean,

30:46

the answer is definitely answer this first. mean, the

30:48

answer is definitely emphatically going to be working you

30:50

know, you're probably not going to be

30:52

working in astronomy, but hey, you know,

30:54

there's loads of things you can do

30:57

with it. with I mean, the big

30:59

secret is that most PhD students, let alone

31:01

let alone... astronomy and then graduates

31:03

go on to work in completely different areas.

31:05

That shouldn't really surprise us. Only a limited

31:07

number of hired astronomers or there's a vast

31:09

number of only a number of people

31:11

that are interested in it. And we at the

31:13

a actually collect examples every so often because we

31:15

wanna know what people are doing. And

31:17

the last time we did it, we found

31:19

people using their skills in this amazing number

31:21

of areas. And they were doing things like

31:23

data science in the to So no surprise And

31:25

kind of processing all these big data sets,

31:27

doing that in the home office so often because we

31:30

want to know cancer cells, you know, using machine learning

31:32

learning techniques to try and identify

31:34

cancer cells cells done that with done that

31:36

well It's just a as of just a

31:38

right? of imaging, right? Exactly, School teaching teaching definitely,

31:40

really inspiring for teachers, really good subject

31:42

for them, and even conserving paintings in the

31:44

National Gallery. I think even you know, it's

31:46

a fact that the technique is being

31:48

used in National a whole range of things

31:50

they could really do with them. So that

31:52

is a good course to do for that

31:54

reason, you know, you don't have to

31:56

use their skills in those areas, but you're

31:58

going to get do with them. degree. You're going to to

32:01

be a literate. literate. You're going to be

32:03

able to do a lot of different

32:05

things. if if good enough to do astrophysics,

32:07

you're pretty much good enough to try try

32:09

at a lot of other things, a too.

32:11

other I'm going to have to say, my

32:13

case, I'm not recommending, say, in my music,

32:15

for example, because the world say I doesn't

32:17

need that. But, know, example because the world really doesn't of

32:20

astronomers yeah but there are very of astronomers who do that very

32:22

not going to encourage me to sing.

32:24

I can encourage me to sing I can tell you. Becky will

32:26

come. I time will come promise that you ate is waiting.

32:28

yeah, I mean yeah I for this question,

32:30

though, I always say Astro is

32:32

basically is basically Like applied many things, right? things,

32:34

data science, science, problem problem solving,

32:36

applied software development as days as

32:38

well. Applied teaching, applied there's so

32:40

so many skills that you

32:43

learn from doing astrophysics. like Robert

32:45

was was saying, like you've been in

32:47

many different things. things. And I

32:49

mean, even I'm an example,

32:51

right? Fresh out of my

32:53

undergraduate degree degree and astronomy at

32:55

Durham, I got hired on

32:58

an engineering graduate scheme. graduate scheme,

33:00

right. So that was like in the world of

33:02

work in engineering and they of of their process was

33:04

like, yeah, we hire both physicists and engineers

33:06

because almost the physicists haven't learned the bad

33:08

habits at university. We could like train you

33:10

up fresh, you know, you know how we want want

33:12

you to be trained. obviously I realized that

33:14

wasn't for me and I did come back

33:16

to academia academia I have got mates that

33:18

did, you know, know physics astronomy at uni

33:20

with me that are in data science, teaching,

33:22

you finance, you know, there could be anything

33:24

from like and all and all the stats

33:27

that come with that to, you know, or

33:29

or anything like that medical physics Rob said, said, It's

33:31

just whether that's working with the big

33:33

machines the doing a lot of the sort

33:35

of research side of things for side of things for

33:37

of... sort of... skills you've learned from master physics.

33:39

people in publishing in well, whether that's

33:41

that's you know, publishing public science books,

33:43

like books, or books, or it's publishing, like,

33:45

as in academic publishing. people working in people

33:47

working in the civil service. people who've

33:49

got a friend that works at

33:51

the works at the right? Office, right? Because whether, again, again,

33:54

it's satellites, you're just pointing the

33:56

satellites in a different direction, right? looking

33:58

down at at earth not open to space. And

34:00

I I think one thing I want to

34:02

get across right now is that there is

34:04

a weird that of is a that of like idea that like

34:06

if you do that a you do degree like

34:08

a science PhD, and then you don't go

34:10

on to be a scientist. It's it's.

34:12

weirdly as a failure, don't see it

34:15

like that at all. that at like, I'm if

34:17

you wanna spend three years doing a PhD a

34:19

PhD in know, some area of research, or four

34:21

years doing an undergraduate doing you love the

34:23

subject and you think it's really cool and

34:25

you wanna contribute to the tiny, know, in

34:27

your tiny way to the sort of collective

34:29

human knowledge that we have, you know a great

34:31

way to spend three years of your life.

34:33

Do you know what I mean? And then

34:36

if you go on and do something else

34:38

that's another great way of spending to many years

34:40

of your life, of your life. That's great. It's

34:42

mine to change direction. I I totally agree because I

34:44

think, so I did did physics at Nottingham. I

34:46

I did a master's, I didn't do

34:48

a do a because I knew that

34:50

I didn't want to do a PhD,

34:52

a but I still loved physics. I

34:54

didn't let that. that... you know know, I

34:56

just thought of a different way that

34:58

made it more suitable to my skills

35:00

and what I could do. But I've

35:03

got friends that have gone on to

35:05

be that have gone attorneys and medical attorneys and

35:07

Some are doing coding for are doing coding for

35:09

like massive well. it's just like, and it's

35:11

This is just really, there are so

35:13

many skills that you pick skills that you pick

35:15

path from from to Google, by the way,

35:17

Google by the way is worrying if so up working at

35:19

Google. them working at Google. yeah, exactly. So I

35:22

think, I I mean, I think. I totally

35:24

agree with you you both that... if

35:26

you can get your head around around I

35:29

think you can get your head around

35:31

quite a lot of things and it's

35:33

totally fine if that is not something

35:35

in academia. and it's can make podcasts, if that

35:37

is not something in know. doing it, You but

35:39

not this one. hey, I'm not doing it,

35:41

but nod this one. Okay, just really contributing to

35:43

the whole, do you wanna be

35:45

when you grow up to the whole, a do

35:47

want to be can be anything you wanna

35:50

be. can be a they say, You an

35:52

astrophysics degree and then do a want

35:54

they'll blame you, is he? Yeah, hey, that's

35:57

fine, it's It's fun.

35:59

Okay, so Becky can you help with

36:02

this follow-up question from Sam after listening

36:04

to our fast radio bus episode and

36:06

they've written to say After listening to

36:08

your podcast on fast radio bursts, I

36:10

would like to know more about how

36:12

experts decide where to look for fast

36:14

radio bursts. Your guest Stuart mentioned being

36:16

able to get time on JWST and

36:18

a sample skyshot, but since FRBs are

36:20

so short and so unpredictable, how do

36:22

experts decide where to aim? Yeah, so

36:24

I mean, it's a great question, Sam,

36:26

so the big radio telescopes that detect

36:28

these flash radio bursts like... they don't

36:30

aim right they stare at the biggest

36:32

patch of sky that they count at

36:34

one time in the hope of detecting

36:37

one and the hope of you know

36:39

pointing in the right direction at the

36:41

right time and but you know they

36:43

could easily be missing so many fast

36:45

radio bursts in a night just because

36:47

wrong place wrong time right In terms

36:49

of J-D-B-S-T follow-up, like the field of

36:51

view of J-D-B-S-T, compared to a radio

36:53

telescope, it's really, very small, right? This

36:55

isn't something you can, like, you can't

36:57

search for F-R-B-s in the hope of

36:59

detecting one with J-D-B-I-I-T, because you just

37:01

can't mobilize the telescope quick enough to,

37:03

like, What it's more about is finding

37:05

the host galaxy that the fast radio

37:07

burst has gone off in. So whatever

37:09

object is producing this fast radio burst,

37:12

which galaxy does it live in basically?

37:14

And oftentimes there doesn't seem to be

37:16

a galaxy in the direction that the

37:18

fast radio bursts seems to have come

37:20

from, at least in sort of like

37:22

the archive imaging we have from like

37:24

ground-based telescopes, right, that obviously, you know,

37:26

can't see things as faint as JDAST

37:28

counter in any sort of resolution. So

37:30

what we do with JDAUST is this

37:32

sort of, as you said, like a

37:34

sky shot where we point JDAUST in

37:36

the direction we think that the fast

37:38

radio radio bursts has come from and

37:40

just sort of like collects as much

37:42

light as much light as possible as

37:44

possible and be like possible and be

37:47

like Is there a galaxy there that

37:49

we can now? to take the generous

37:51

tea. Or sometimes we do find that

37:53

there's a smudge of a galaxy there

37:55

in the direction we think the fast

37:57

radio verses come from, but we don't

37:59

know the distance very well because again

38:01

we can't really resolve it. We've not

38:03

been able to get what's known as

38:05

a spectrum where you take the light

38:07

and you split it into its like.

38:09

trace of how much light each wavelength

38:11

you're receiving. And from that you can

38:13

pinpoint things to say how much has

38:15

the light been redshifted by the expansion

38:17

of the universe to work out how

38:19

far away it is. And so with

38:21

JWST we can actually look at their

38:24

galaxy more detailed, get that spectrum that

38:26

we need to pinpoint where the fast

38:28

radio burst is coming from and how

38:30

far away it is. And that gives

38:32

us a lot of information because if

38:34

we know how far away the fast

38:36

radio burst is, then from how bright

38:38

it appeared to us when it went

38:40

off. and so we can put some

38:42

limits on like how much energy was

38:44

involved in the production of this fast

38:46

radio burst and things like that. That

38:48

gives us a better idea of like

38:50

what's producing them, you know, is it

38:52

magnetars, like everybody suspects. And also perhaps

38:54

if that's changing with how distant we

38:56

go out as well and with how

38:59

distant we find fast radio bursts, is

39:01

there different things that produce them and

39:03

does that change with time in the

39:05

universe? Like lots of questions like that.

39:07

Amazing, thanks Becky. And Robert Lucy on

39:09

Instagram asks, why can't we predict or

39:11

understand the sun's magnetic field? Yeah, thank

39:13

you Lucy. When I read this I

39:15

thought, how is that Lucy Green's solar

39:17

physicist who I know quite well, trying

39:19

to catch me out, but probably not.

39:21

She's secretly marking you. Exactly. I definitely

39:23

feel judged. I definitely feel judged. But

39:25

it is a very fair question. I

39:27

mean, the answer is we can predict

39:29

the 11-year solar cycle of activity reasonably

39:31

well. So we know that the number

39:34

of sunspots rises and falls over that

39:36

time, and then when there are a

39:38

lot of sunspots, the sun is generally

39:40

more active, so there are more There

39:42

are more coronal mass ejections when big

39:44

eruptions of material are rejected in space

39:46

and those rise and fall over that

39:48

time. And then a new cycle begins

39:50

with the poles of the magnetic field

39:52

reverse. So you go north to south

39:54

and south to north. And right now

39:56

we are at solar maximum. That's why

39:58

we've had two major... displays of a

40:00

roaring this year. we've

40:02

also already we've signs seen signs of the

40:04

next up and there up, and there was a

40:07

researcher presenting at our National Astronomy meeting in Hull back in

40:09

in July. details are But the details are

40:11

much, much harder. And I remember a

40:13

decade ago harder. And I physicists were absolutely adamant

40:15

that solar activity was headed to record

40:17

lows. And that was going to happen

40:19

in the next few years, and it

40:21

was going to be like the kind

40:23

of very low numbers we saw back

40:25

in the few years. And it century, was going long

40:28

after people kind started observing the we saw back

40:30

in the 17 telescopes and it didn't work out

40:32

like that like know it was low was

40:34

it's high again high again we also also... definitely

40:36

predict exactly when a large when a large is

40:38

going to produce a flare you know

40:40

we see them a don't know exactly

40:42

when they're going to eruptive at all

40:44

when a coronal mass ejection will happen at

40:46

direction it'll take ejection we can only

40:48

guess that it'll probably be only guess we

40:50

see a big Sunspot group in the

40:52

first place we just don't know exactly

40:54

when group that's because the Sun is not

40:56

this sort of super smooth that's because the

40:58

model not this a of plasma to model particles

41:00

of fields, currents of material, you know, know,

41:02

flows in and out of the atmosphere, in and out

41:04

of the and under even tornadoes on

41:06

and under its surface, and trying to

41:08

work out how that that we together

41:11

is really hard. processes that the sense that

41:13

we don't understand a lot of

41:15

the processes that make it happen on

41:17

a or but understanding will predicting how

41:19

it will change over time is quite

41:21

hard. So we do understand how

41:23

the magnetic fields work. We do understand

41:25

that, you know, the interaction with

41:27

charged particles, the fact they're tied together

41:29

with electromagnetic forces, that's okay. But trying to But trying

41:32

to estimate those long is trends is

41:34

really very, very difficult that that cycle or cycle

41:36

or 22 -year cycle, if you prefer, you

41:38

know, when the polls go know, when the the back

41:40

to the position they were in before.

41:42

you know, So Lucy, you know, frankly, doing, but if

41:44

I don't know what you're doing, a

41:46

but if you take up a solve this problem,

41:48

then you solve this problem, on probably be

41:50

on your way to for a a Nobel

41:52

because because astronomers are really struggling with

41:54

it. with it. Okay and Becky we I'm thinking

41:56

we have another black coal question

41:58

for you. you. Amazing. Yeah. Obviously. Abby Girl

42:00

Smith says, hi, love of the podcast.

42:03

My question is, why do black holes

42:05

expand and shrink? Oh, good question. So,

42:07

I mean, expand and shrink. I think

42:09

you mean they're like the size of

42:11

them. So like the size of the

42:14

event horizon, which was like inside that

42:16

we class as the black hole, right?

42:18

So the size of the event horizon

42:20

is actually correlated with the mass of

42:22

the black hole. So how heavy it

42:24

is. Blackhaws expand if they grow in

42:27

mass. So if they take in more

42:29

material over time, so we see that

42:31

in what we call x-ray binaries where

42:33

you've got two stars that are orbiting

42:35

around each other, one goes supernova, becomes

42:38

a black hole, and the other star

42:40

is close enough to start almost like

42:42

feeding the black hole and like the

42:44

black hole is material off that one.

42:46

And so in that respect, the black

42:48

hole will expand its radius, its vent

42:51

horizon will grow, and therefore... the black

42:53

hole is expanding if you will as

42:55

it's growing in mass. Shrinking however is

42:57

an interesting question because you think okay

42:59

well if black calls expand because they

43:02

get heavier then they should shrink when

43:04

they get lighter and they lose mass.

43:06

But the whole point of a black

43:08

hole is that all the material and

43:10

the light and everything is trapped there

43:12

right? That's the point of a black

43:15

hole. However, enter Stephen Hawking stage left

43:17

because Stephen Hawking was very concerned about

43:19

like the fact that black holes seemed

43:21

to break one of the fundamental laws

43:23

of physics, the fundamental laws of thermodynamics,

43:26

right? And is that entropy, it's almost

43:28

like the chaos in the universe should

43:30

increase over time, whereas black holes that

43:32

they're sort of like the Marie condos

43:34

of the universe. They really organize little

43:36

boxes, right? And the entropy seems to

43:39

go down. And so when he was

43:41

looking at the mass of trying to

43:43

figure this out, he sort of came

43:45

up with this hypothesis that essentially there's

43:47

sort of like an interaction of the

43:50

black hole with sort of what's going

43:52

on in terms of quantum physics, sort

43:54

of in this sort of like vacuum

43:56

energy of space. I won't go into

43:58

the details here because it gives me

44:00

a headache every time I try and

44:03

it takes me a good chapter of

44:05

a book every time I try to

44:07

explain this. But essentially what happens is

44:09

you then get radiation given off at

44:11

the event horizon of a black hole.

44:14

You get like a pair of particles

44:16

created, one of which escapes and one

44:18

of which ends up going back into

44:20

the black hole. As Einstein told us,

44:22

E equals MC Squares, if you've got

44:25

lights, energy, escaping, you've also got mass

44:27

escaping. So Stephen Hawking's theory is that

44:29

you have what's known as Hawking radiation

44:31

that allows the black coal to evaporate

44:33

over time or to shrink, as Abigail

44:35

put it, right? That, however, is still

44:38

just complete hypothesis. Like those papers were

44:40

published in the early 70s. We have

44:42

no observational evidence that this does happen.

44:44

that we've ever detected like this kind

44:46

of radiation that you could get from

44:49

a black hole. It could just be

44:51

that it's so red that this ever

44:53

happens that of course we haven't ever

44:55

detected it yet or there's not a

44:57

black hole close enough for us to

44:59

detect the tiny amount of radiation that

45:02

you would expect. Maybe if there's a

45:04

planet 9, 9, that's a planet of

45:06

the source system that would be an

45:08

ideal place. That would be an ideal

45:10

place to test for this system. That

45:13

would be an ideal place to test

45:15

for this as well. We know what

45:17

about calls expand, whether they can shrink

45:19

or not is another thing entirely. Okay,

45:21

thank you. And a final one for

45:23

both of you from Samdowns on Instagram,

45:26

do you think there are aliens out

45:28

there? Robert? You know, I kind of

45:30

do, but with the caveat that they

45:32

might be really simple aliens, you know,

45:34

really much harder question is whether there's

45:37

any advanced life, even remotely like us,

45:39

which might be extraordinarily rare. I mean,

45:41

I have to say a cause as

45:43

well, we... At this point in time,

45:45

we haven't found any evidence for any

45:47

life. There's no hard evidence anyway. We

45:50

found hints of things, you know, we

45:52

found worlds that could support it, chemical

45:54

processes that allude to it, but no

45:56

more than that. So, you know, we're

45:58

a long way. from this. this.

46:01

But you know, they're not here. The They're

46:03

not here. The Fermi paradox is

46:05

is applying, know, the aliens haven't haven't

46:07

visited the earth, whatever, whatever you might on

46:09

on some channels. And that's not really

46:11

surprising given how big how are. It's

46:13

a really difficult thing to travel between

46:15

the stars. to travel between the

46:17

stars. Becky. Sorry, one second. some

46:19

strange noise a now I'm convinced that the

46:22

cat's in here with me. The cat

46:24

is in there because I saw it

46:26

in here with me. The cat is in there because I saw

46:28

the background. walk open! Oh, didn't even rail phone.

46:30

Yeah, I saw her watching in the background. Yeah,

46:32

your cat saw her cat used to, my

46:34

cat, I can't use to play

46:36

the piano her by walking, that used

46:38

to terrify me Yeah, your cat is in the

46:40

on the far back of the

46:42

sofa? used to play the piano at that was

46:44

That interrupted your previous answer, being

46:46

like, oh, hello. Anyway, pips in the room. Aliens aren't

46:48

in the room with us, but the cat in the

46:50

room. with aren't in the room

46:52

with us, but the cat is. has

46:54

to be I agree with has I

46:56

think... on another has to

46:59

be life that has started on

47:01

another planet in our own in the universe.

47:03

the Whether that's in our don't the Milky

47:05

Way, I don't know, or, you know,

47:07

more likely a I think I think just

47:09

because everything we see see it comes

47:11

to life, life, like... Do I? She's scratching it again again.

47:13

Like, tar degrades, like surviving in, you know, the

47:15

vacuum of space on the outside

47:17

of the interstellar space station. Space We

47:19

recently saw that, you know, saw that, you

47:22

a a chunk of asteroid that we

47:24

brought back from the asteroid on the right,

47:26

on the Hayabusa -2 mission, Jax's

47:28

mission went to the asteroid and brought it

47:30

back to brought it back to Earth. Earth life colonised

47:32

the surface of that of that asteroid and

47:34

quickly and very happily. you know, alien

47:36

rock that know, alien rock to, has

47:39

never been exposed to, you

47:41

know, a clean room and been in a

47:43

clean room it's got got slight

47:45

contamination that all of a sudden

47:47

just proliferated. So. So think

47:49

as Ian Malcolm and Jurassic Park so wonderfully

47:51

puts it, life puts it, life way, away.

47:54

And I and I think it would

47:56

be very rare indeed if nothing, if we'd

47:58

be the only one. you know. where those

48:00

conditions are right. I think if you think about

48:02

the numbers of how many stars there are and how

48:04

many galaxies in the universe and how many planets they

48:06

must have, blah blah blah. Yes, I think life must

48:09

exist somewhere, but I do not think that they have

48:11

visited us. at all. Okay, well we'll be getting into

48:13

that topic more in January 2025. I'm so excited.

48:15

So thank you to everyone for your questions. Do keep

48:17

sending them in. And Robert, as always, what can we

48:20

see in the night sky over the holidays? Over the

48:22

holidays, well, the bleak mid-winter, you know, accuse carols or

48:24

something, I'm not going to sing. But it is just

48:26

after the December solstice. So for the Northern Hemisphere, it's

48:28

the longest nights the year, pretty much. the other way

48:31

around if you're in the southern hemisphere, wherever you

48:33

are in the word, Ryan is now really dominant in

48:35

the late evening, so I have the brightest consolation, the

48:37

whole sky, two first magnitude stars, Beekle, Juice, and Rigel,

48:39

the belt term, you know, a wonderful thing to see,

48:42

particularly, it's a signpost of the stars around it, so

48:44

you can, you know, you can follow up and

48:46

down and all that kind of thing. do look at

48:48

the Nepidr under the belt and definitely have a look

48:50

around if you were given a pair of binoculars that

48:52

we recommended for Christmas, you know as a potential gift

48:55

or maybe you got some for yourself or borrow some

48:57

but you know really opens up your enjoyment of it.

48:59

Why are you there if you're in the Northern Hemisphere

49:01

look down from the belt stars down to Sirius

49:03

which is the the brightest star in the whole night

49:06

sky. Now apart from that Jupiter is sitting above Orion

49:08

and Taurus it's completely look at it, look at the

49:10

belt, the weather systems. And you might also, if it's

49:12

half decent, be able to see things like the moons

49:15

passing in front of it and their shadows. And

49:17

I was looking up, there's a predictor on the Sky

49:19

and telescope website, which we should probably link to actually,

49:21

but on Boxing Day, the closest in Moon IO does

49:23

this for people in the UK, starts at 816 in

49:25

the evening and it moves away by 1048. So it's

49:28

really well placed. So if you have a clear sky

49:30

that night. have a look. It's really quite a nice

49:32

thing to see the shadow moving on and off.

49:34

Venus is high in the sky after sunset, looks slightly

49:36

fatter than a half moon through a telescope, obviously dazzlingly

49:39

bright, and it's good for the next couple of months.

49:41

And if you're up before dawn, and you've got a

49:43

good for the next couple of months, and you've got

49:45

a good for the next couple of months, and

49:47

you've got a good for the next couple of months,

49:49

and if you're up before dawn, and you've got a

49:52

good for the next couple of your up before dawn,

49:54

dawn, dawn, you've got a good for the next couple

49:56

of the next couple of a good for the next

49:58

couple of months, dawn, dawn, dawn, and if you've

50:00

got a good for the next couple of a good

50:03

for the next couple of a good for the next

50:05

couple of a dawn, dawn, dawn, dawn, dawn, dawn, dawn,

50:07

dawn, dawn, dawn, and if you've got a good for

50:09

the next couple of a good for the And finally,

50:11

do look out for the quadrantids meteor shower that's peaking

50:14

on the night, the second to the third of January,

50:16

more or less, it depends on where you are

50:18

in the world. It's very, very sharp in its peak

50:20

and that's actually best for the Pacific this year. But

50:22

even if you're in the UK, you might see say

50:25

25 meteors an hour and helpfully the moon is a

50:27

thin crescent, a waning thin crescent, so it won't interfere

50:29

too much. Now I have to say I've always

50:31

really struggled struggled to see it. Not always what it

50:33

could be. What are you talking about? I'm going to

50:36

try again. I'm going to try, I'm determined to try

50:38

again and I encourage you to do the same. Do

50:40

go and have a look, you know, wouldn't it be

50:42

great if we actually got that? It's really quite a

50:44

strong shower. It's just, I've never managed to see it

50:47

in 50 years, well maybe not 50 years, 40

50:49

years of trying. I have something to add to this

50:51

as well for the Christmas star gazing period. I want

50:53

to give a warning. to all the parents of children

50:55

out there that the International Space Station can look very

50:58

convincingly like Father Christmas's sleigh. And I wouldn't want anybody

51:00

to confuse the two because it was very fast,

51:02

it's very bright. So there is actually an International Space

51:04

Station Passover of the UK at 6am on Christmas morning.

51:06

So if you have been... gotten up that early because

51:08

you have children maybe a little look out of the

51:11

window to see it passing directly overhead just past six

51:13

o'clock and you know just be very careful that

51:15

your children don't confuse it for Santa Claus because I

51:17

obviously wouldn't wouldn't want that. to to happen.

51:19

a good public health a good a

51:22

health warning. They're public safety if

51:24

you'd like if you'd like to

51:26

know own own that no that

51:28

no confusion happens, spot station from NASA is

51:30

the the website that you

51:33

should Google, or you can put

51:35

in your area and see

51:37

where to look and when

51:39

to look as well. as well. Yeah.

51:41

it's brilliant. Well I think that's I

51:44

think that's it for

51:46

this episode and for this

51:48

year. be back in be back in

51:50

a month's time with the with

51:52

the search for life. will come

51:55

back with that. It is

51:57

gonna happen. We've said it

51:59

so much that it's We've have

52:01

to go and find

52:03

people to talk to. I have to

52:05

people to talk to, the

52:08

people to talk to are

52:10

like, sorry, we're busy with

52:12

searching for the alien life.

52:14

the people to talk to say. like

52:16

sorry will get that to

52:19

you. But thank you to

52:21

everybody who sent in questions

52:23

for this episode. I really

52:25

enjoyed this episode. Thank you

52:27

so much. We do have

52:30

a growing pile of questions we

52:32

we will keep adding

52:34

to it as well. So

52:36

please do because we have

52:38

these bonus episodes, right, where

52:41

we always do the Q &A

52:43

as well. the So if

52:45

you have a burning question

52:47

for the team, email it

52:49

to team, email it to .at at r-a-s.ac.ac.uk or

52:52

you you can find us

52:54

on on Instagram at Super Massive Pod and we'll of

52:56

course try and cover your

52:58

questions in a future episode.

53:00

episode. if I can be

53:02

really cheeky and ask for a

53:05

a Christmas present for us, us,

53:07

if if anyone wouldn't mind

53:09

rating and reviewing the podcast

53:11

and it really helps really we

53:14

love seeing all of your

53:16

your So thank you So

53:18

already done that. That's already done that.

53:20

we will be back with

53:22

more episodes for you in for

53:24

you as well. but then, everybody,

53:27

happy holidays and most importantly,

53:29

importantly, happy start gazing.