Making Sense of the Cosmos

as an astronomer

i feel blessed to have seen the skies

from some of the most remote

observatories in the world

in exotic places like the atacama desert

in chile

the island of la palma and the karoo

desert in south africa

the night skies seen from these places

are dazzling

beyond description yet none impressed

and touched me as much

as when observing the heavens from bumba

a village

in the north of senegal there

with a brilliant three-dimensional star

canopy above

the nightly sounds of nature frogs

insects donkeys mingled with the sounds

of village life

the smells of food and a smoldering fire

brought to me by a sudden breeze

a full multi-sensory experience

and it reminded me that our

understanding of the universe

is profoundly grounded in our human

perception

at first sight and that expression

speaks for itself astronomy is a very

visual science

our only window to the universe for many

millennia

has been through visible light light

that we can see with our eyes

but we humans are not purely visual

creatures

as i was sitting under the night sky in

bumba

i could see the stars but i also

wondered

what they would sound like how it would

be to be

near them we should not forget our other

senses

such as hearing smell taste and touch

sometimes we are blinded by our eyesight

too much focus

goes to visual stimuli let’s open our

other windows to the universe

let’s explore with our other senses to

make sense

of the cosmos close your eyes

for a while

think of the voice of someone you love

you can pick up that voice among the

voices of a thousand different people

we can also recognize a person a place

food by using our sense of smell

smell is closely linked to taste

our sense of taste helps us to avoid

dangerous foods

so we can stay healthy as humans

and then touch our skin

is the most forgotten sensory organ but

think of a kiss on your forehead

or a loving embrace or the first sun

rays on your face

after a long winter

we and our senses evolved on our planets

our whole human experience is defined by

them

and our brains and imagination developed

with them

now let’s tune these senses to outside

of our earth’s atmosphere our human

bodies are adapted

to living on our planet and space is a

hostile environment

the emptiness of space makes that our

sense of touch

smell taste and hearing cannot directly

perceive the universe

but nothing can stop our imagination

from exploring and making sense

there is a whole new and unexplored

sensory playground out there

for which light that can reach us from

very far

is the messenger all the light we can

see in the night sky

comes directly or indirectly from stars

it could be reflected sunlight on the

moon or on a planet in our solar system

light emitted by a star a hundred years

ago

or light from an entire galaxy an island

of stars

millions of light years away and all

that starlight

gives us information not only about what

universe looks like but also about what

it

feels smells tastes and sounds like

out there

first of all it is generally cold out

there

very cold but there are zones where it

is scorching hot

the dots of light you see in the night

sky the stars

are very hot typically thousands of

degrees celsius

on their surface and millions of degrees

celsius

in their interior have you ever wondered

what outer space

smells like trying to smell in space

is dangerous space is mostly a vacuum

therefore there aren’t many molecules to

smell

and the various fluids in your body will

quickly balance out with your

surroundings

the air in your lungs will expand

violently

your saliva will evaporate from your

mouth

and then your blood will boil

a spacesuit is no luxury item it allows

you to survive

astronauts after coming back from a

spacewalk and taking off their helmet

have noticed a celestial smell on their

spacesuit

and they have described it as hot metal

and burnt steak

with hints of gunpowder raspberries and

rum

and much further away using light as a

messenger

astronomers were able to identify a

chemical in a big dust cloud

at the center of our galaxy the milky

way

on earth this chemical is responsible

for the flavor of

raspberries so we can presume

that space tastes like raspberries

could be worse and let’s now tune our

ears to the cosmos

our universe is full of sound in the

depths of space

planets of all flavors crackle and roar

stars are ringing like giant bells and

merging black holes

occasionally send a chirp through the

fabric of space-time

i study stars and in my research i try

to understand the inner workings of the

stars

through their vibrations or their sounds

one could say i study stellar music to

find out what the instruments or the

stars

are like stars are born

they live and die just like us but they

are much bigger

they are giant spheres of gas our own

star

the sun has a volume of more than a

million times the earth

but compared to some others it is just

an average star

stars are not only bigger they also live

much

longer a human lifetime of say 90 years

is just a blink for a star stars can

live millions to billions of years

in some phases of their long lives the

stars can get a bit unstable

a similar thing happens to us humans

just think of puberty or a mid-life

crisis

in these phases the stars start

vibrating

they get sound waves traveling through

their interior

these sounds are inaudible to the human

ear

because they are too low in pitch but

they make the stars vibrate like giant

musical instruments

we cannot hear their sounds but these

sounds affect the light that the stars

emit

we can record these brightness

variations of the stars and thus figure

out the sound waves ringing through the

stars

and when we speed up the vibrations they

become audible to the human ear

and we can enjoy the characteristic

sound or the timbre

of each star let’s listen to a few of my

favorite stars some of which you can see

with a naked eye in a bright night sky

polaris the north star or the pole star

is a rather bright star

that lies nearly in a direct line with

the earth’s rotation axis

above the north pole because of that

polaris stands almost motionless in the

sky and all the stars of the northern

sky appear to rotate around it

it makes an excellent fixed point for

navigation

but nothing lasts forever because the

earth’s rotation axis moves

the celestial pole will move away from

polaris after the 21st century

the star’s distance to earth is about

400 light years

which means that we are now observing

the light

that left a star about 400 years ago

we see the star as it was in the past

this holds for all stars we see in the

sky

when we look out we look into the past

in fact polaris is a triple star system

composed of three stars orbiting each

other

the brightest one is a so called

supergiant star

this huge star is indeed almost 40 times

larger than our sun

and more than a thousand times brighter

but its brightness is not constant

it fluctuates every four days

in this process the star shrinks getting

hotter and brighter

and swells up again getting cooler and

dimmer

it is as if it is breathing very slowly

this breathing pattern has been followed

for centuries

and we see small variations in it

so even the most fixed star in the sky

polaris is a variable

not so far from polaris in the northern

sky another bright bluish star may catch

your attention

its name is beta sifii or alphyc

the arabic word for hurt like a herd of

sheep

the name is appropriate because it is in

fact again a triple system

the biggest and hottest star in the

system is again a variable

expanding and contracting every few

hours

the star is much hotter heavier and

brighter than our sun

but since we observe it from a distance

of 700 light years

it looks a bit fainter than polaris

this massive star is in the prime of its

life

fusing hydrogen the simplest element in

the universe

into helium deep in its core

stars are in fact factories for making

chemical elements

the elements that we find everywhere on

our planet

and for alfiek this fusing

will keep it going while it is humming

its star song

for millions of years in the nearer

future

in three thousand years because of the

slow movement

of our earth’s rotation axis alfiek

will become the new star in our

celestial pole

one of my favorite stars a star i have

been studying for almost 20 years

has a similar breathing pattern as

polaris but faster

instead of four days it contracts and

expands

in about half a day for this star

you need binoculars our telescope to see

it

but this is the sound of rr larry

it sounds like music to my ears and just

like the voice of my loved one

i can pick it up among thousands of

stars

it is a very old star we could say it is

a retired star

past the prime of its life yet it is

still doing very important work

it is fusing helium into carbon and

oxygen

these are the two most important

elements making up our human body

and our understanding is that they could

only have been formed in stars

maybe in the distant past say

7 billion years ago this star was

comparable to our sun

but today it is singing a beautiful swan

song

while creating elements essential for

life

at the end of their lives stars return

the elements they have created

in their lifetime back into the universe

for a star like our larry its end will

happen rather peacefully

as the core of the star shrinks into a

white dwarf star

the outer layers are expelled into space

a beautiful colorful nebula

full of elements around what remains of

the star

for a more massive star like alfiek

the end will be more violent in a

supernova

a rare and powerful stellar explosion

in which the star briefly becomes a

million times brighter

and complex elements are propelled far

into empty space

iron is a typical element stemming from

such violent supernova events

the iron in your bloods in my blood in

any human’s blood

regardless of their origin skin tone or

convictions

was likely produced in the same

supernova in the distant cosmic past

we are all truly blood brothers and

sisters

from the remnants of previous

generations of stars the stellar

graveyards

new stars and planets are formed that is

how

our own sun and the planets in the solar

system among which the earth

came into being 4.6 billion years ago

and how we evolved on our planet from

the same basic elements

we are stardust star stuff from the

nitrogen

in our dna the calcium in our teeth

and the iron in our blood most of the

essential elements

of life and the basic elements of all

the things we can

touch smell and taste are truly made in

the stars

now let’s return to our own star

when the sun’s scattered light brightens

up the sky

and you can feel its warmth even at a

distance of 150 million kilometers

you may not suspect that it is also

buzzing with sound waves

millions of vibrations are traveling

through the sun

thanks to these vibrations we can get

some insight

into what is happening inside of the sun

and we can even get a good estimate of

its age

in this way we learn about the past the

present and the future

of our own solar system by studying

other stars we can understand more about

our own star

and get some perspective

just like the much more massive star

alfig

our sun is in the prime of its life

deep in its interior it is fusing

hydrogen into helium

converting mass into energy in the

process

it will continue to do so for the next 5

billion years or so

and then it will retire swell up

and become a red giant star for a while

our son will die a peaceful death as a

white dwarf star

surrounded by a beautiful nebula

when this happens our species will

probably not be around to witness it

but it will be a feast for the senses

as blood brothers and sisters we are

also children of our sun

our senses developed on a planet fueled

by the sun

our eyes are most sensitive to the light

the sun mostly radiates in

our skin is adapted to the balmy

temperatures on planet earth

with its protective atmosphere at the

right distance from the sun

and our ears nose and taste buds are

adjusted to the pressure and composition

of our precious atmosphere and biosphere

now you understand that when i raise my

gaze

on a clear night i experience much more

than the magnificent view of twinkling

mysterious dots in the sky

looking up means turning inside

i recognize my pet stars and i imagine

their immensity their heat the gigantic

forces in their interior

i imagine their sounds that tell me

about their long history

making new elements that form the basis

of life of our human life

and i know that my own human existence

my body and its perceptions are

intimately linked

with the universe we observe today

thank you