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