Cosmic origins
intro
www.astro.rug.nl/~weygaert/cosmic_origins2017.html
multiple choice ipv written exam
Cosmology – in search of our origins
cosmic microwave background – 1965 – ultimate conformation that the universe began in an instant
hot extremely dense explosion - 13.8 billion years ago - 2.735
kelvin entire universe - we come from tiny variations in
temperature/soundwaves (blue/orange variations)
everything was born in the big bang, time, universe etc didn’t exist
before the big bang
Universe was formed in the hot big bang is expanding + flat
Cosmology
- van dale – astronomical science or theory of the universe as an ordered unity / study of the
structure and evolution of the universe
- broadest sense – human enterprise joining science, philosophy, theology and the arts to seek
to gain understanding of what unifies and is fundamental to our world
- scientific – study of large and small structures of the universe
essential and existential questions occupying humanity since dawn of civilization
- where does the world come from?
- what is the world made of?
- how/when did the world begin?
- did it begin at all?
- how big is the world? (finite/infinite)
- what is the role of humans in the cosmos?
- what is the fate of the universe?
Fundamental questions
2 neutron stars colliding created all the gold, silver metals we find on earth
In an infinite large, old and unchanging Universe, each line of sight would hit a star so the sky should
be as bright as surface of a star/solar surface. yet the night sky is dark, this is because the universe is
not infinitely old, but has a finite age (13.8Gyr) in our universe, there are plenty of spots where a line
of sight do not hit a star – Olbers paradox
Edgar allen poe – if the universe had a beginning, it would become larger and larger causing the
night sky to be dark (1842) ???
cosmic depth = cosmic time because we measure distance in light years, the further
(deeper into the universe/farther away from earth) you go, the larger the region you
can see but also the further you look in time,
1
,every smudge = a galaxy containing 100-200 billion stars (20.000 to 40.000 light
years broad)
reddish galaxies have shifted light light shifted to the red because of the
expanding of the universe
2010 put in a camera that
can see infrared light,
which is important
because the older light
has shifted to red light so
if you want to see further
back in time you need a
camera that can see
infrared light.
cosmic microwave background – 379000 after the big bang – earliest view of our cosmos
there is only one (visible) universe = limitation in studying it because in other sciences you can
compare things to each other to study it but when there’s nothing to compare it to, it’s harder to
study it.
Ancient Skies & heavenly rhythms
cosmology is as old as humankind
Presumably as soon as humans developed language and art, the use of symbolism for expressing
more profound and abstract thoughts, they started to study the world around them.
Very early cosmology was very local, the universe was what you immediately interact with and
involved weather, earthquakes, sudden environmental changes etc. things outside daily experience
were supernatural
The sky was identified with the supernatural, its serenity and regularity with the action of forces –
gods beyond control of the humans.
At the same time it was recognized that the celestial phenomena were influencing our daily life;
- e.g. seasons corresponded to motions of stars on the sky
- that suggested that ultimate forces in our wold were to be seen on the sky
the key to unravelling the mysteries of the sky and the forces that shape and formed our world and
universe were to be found in the regularities in the celestial motions the astronomy of that
formed the basis for many cosmological ideas and thoughts
Astronomy existed far before the dawn of civilization and is the oldest science of humanity, people
became aware of patterns in the night sky and change and regularity of the night sky.
Astronomy was important for civilization
- farming and hunting
o regularity of nature reflected in the sky
o seasons
- religion
o gods identified with stars and celestial bodies
o astrology: human fate connected to heaven
- farming and religion
2
, o calendars and timekeeping
- navigation
- land surveying
Stars are not static but change place daily the night (rise east,
culmination in the south and set west) all the stars rotate
around the polar axis (near the polar star/star polaris)
The sky turns around the north celestial pole, along a circle
parallel to the celestial equator
Lascaux
- first starmap – the Pleiades?
- ice age cave paintings
- 16500 years old
- Rappenglueck – cave paintings contain astronomy – starmap, Pleiades, moon cycle
Oldest constellation = Big dipper / grote beer –
same name all around Eurasian continent +
American Indians + can only be seen on northern
hemisphere, older than 10.000 years before
ancestors American Indians crossed the bering
strait.
summer sun orbit in the sky much larger than the
orbit in the winter lower sun in winter
Ecliptic – sun’s yearly path among the stars =
projection earths orbit on the sky
zodiac sign = constellation in which the sun was at
the moment of your birth can not see your zodiac
constellation on your birthday because the sun is in
front of it and produces so much light you can only
see the sun and not the stars further back
Nabta – Egypt
- oldest astronomical megalithic monument
- 6.000-6500 years old
- complex calendar circle
- marks summer solstice and maybe even the orion belt+shoulders
3
, Stonehenge
- marks longest and shortest day of the year
- built in 3 stages
- 3100BC 300BC and 2600-2000BC
- solar observatory
Newgrange – Ireland
- 3300-2900 BC
- chamber at the end of the corridor is lightened
one day pf the year
Goseck
- Germany
- Europe’s oldest observatory
- circular solar observatory
- winter and summer solstice
stars
Circumpolar star – any star closer than your latitude to your visible celestial pole (north
or south, south pole doesn’t have a polar star) will always be above your local horizon,
so it doesn’t set or rise it goes in a circle above your head rotating around the celestial
pole
As the earth moves in its orbit throughout the year, we see the sun move over the sky,
stars located in the part of the sky visible during the day are not visible as the sun is too
bright. Only stars visible on sky after sunset and the ones rising before dawn will be visible in the
given time of year
Sirius
- helical rising of this star announced the annual flooding of the Nile in Egypt. key importance
for retaining the fertility of the soil around the Nile
Palaeolithic lunar calendars
- ishango – 20.000-25.000 yrs old, linear notches in 3 rows
- Blanchard bone – 30.000 yrs old. lunar calendar on bone
Moon
- 29 days
- w-side moon lit in the evening, e-side moon lit in morning
- changes shape and size during a month
o caused by elliptical orbit around the earth
- moon orbit’s plane oscillates
- we can see more than ½ (~55%) of the moons surface due to its
elliptical orbit
- the moon orbit also rotates itself with respect to the ecliptic plane
resulting in a systematic circular shift of the nodes
- time of the moon to rotate is the same as the time of the moon to go
around the earth that’s why we only see one side of the moon
- The regularity in the occurrence of an Eclipse is therefore the result of 3
periods: - synodic month: motion of moon around earth, wrt. Sun) - draconic month: time
between passes of the moon through nodes of its orbit - anomalistic month shift of moon
orbit, ie. of its perigee and apogee
4
intro
www.astro.rug.nl/~weygaert/cosmic_origins2017.html
multiple choice ipv written exam
Cosmology – in search of our origins
cosmic microwave background – 1965 – ultimate conformation that the universe began in an instant
hot extremely dense explosion - 13.8 billion years ago - 2.735
kelvin entire universe - we come from tiny variations in
temperature/soundwaves (blue/orange variations)
everything was born in the big bang, time, universe etc didn’t exist
before the big bang
Universe was formed in the hot big bang is expanding + flat
Cosmology
- van dale – astronomical science or theory of the universe as an ordered unity / study of the
structure and evolution of the universe
- broadest sense – human enterprise joining science, philosophy, theology and the arts to seek
to gain understanding of what unifies and is fundamental to our world
- scientific – study of large and small structures of the universe
essential and existential questions occupying humanity since dawn of civilization
- where does the world come from?
- what is the world made of?
- how/when did the world begin?
- did it begin at all?
- how big is the world? (finite/infinite)
- what is the role of humans in the cosmos?
- what is the fate of the universe?
Fundamental questions
2 neutron stars colliding created all the gold, silver metals we find on earth
In an infinite large, old and unchanging Universe, each line of sight would hit a star so the sky should
be as bright as surface of a star/solar surface. yet the night sky is dark, this is because the universe is
not infinitely old, but has a finite age (13.8Gyr) in our universe, there are plenty of spots where a line
of sight do not hit a star – Olbers paradox
Edgar allen poe – if the universe had a beginning, it would become larger and larger causing the
night sky to be dark (1842) ???
cosmic depth = cosmic time because we measure distance in light years, the further
(deeper into the universe/farther away from earth) you go, the larger the region you
can see but also the further you look in time,
1
,every smudge = a galaxy containing 100-200 billion stars (20.000 to 40.000 light
years broad)
reddish galaxies have shifted light light shifted to the red because of the
expanding of the universe
2010 put in a camera that
can see infrared light,
which is important
because the older light
has shifted to red light so
if you want to see further
back in time you need a
camera that can see
infrared light.
cosmic microwave background – 379000 after the big bang – earliest view of our cosmos
there is only one (visible) universe = limitation in studying it because in other sciences you can
compare things to each other to study it but when there’s nothing to compare it to, it’s harder to
study it.
Ancient Skies & heavenly rhythms
cosmology is as old as humankind
Presumably as soon as humans developed language and art, the use of symbolism for expressing
more profound and abstract thoughts, they started to study the world around them.
Very early cosmology was very local, the universe was what you immediately interact with and
involved weather, earthquakes, sudden environmental changes etc. things outside daily experience
were supernatural
The sky was identified with the supernatural, its serenity and regularity with the action of forces –
gods beyond control of the humans.
At the same time it was recognized that the celestial phenomena were influencing our daily life;
- e.g. seasons corresponded to motions of stars on the sky
- that suggested that ultimate forces in our wold were to be seen on the sky
the key to unravelling the mysteries of the sky and the forces that shape and formed our world and
universe were to be found in the regularities in the celestial motions the astronomy of that
formed the basis for many cosmological ideas and thoughts
Astronomy existed far before the dawn of civilization and is the oldest science of humanity, people
became aware of patterns in the night sky and change and regularity of the night sky.
Astronomy was important for civilization
- farming and hunting
o regularity of nature reflected in the sky
o seasons
- religion
o gods identified with stars and celestial bodies
o astrology: human fate connected to heaven
- farming and religion
2
, o calendars and timekeeping
- navigation
- land surveying
Stars are not static but change place daily the night (rise east,
culmination in the south and set west) all the stars rotate
around the polar axis (near the polar star/star polaris)
The sky turns around the north celestial pole, along a circle
parallel to the celestial equator
Lascaux
- first starmap – the Pleiades?
- ice age cave paintings
- 16500 years old
- Rappenglueck – cave paintings contain astronomy – starmap, Pleiades, moon cycle
Oldest constellation = Big dipper / grote beer –
same name all around Eurasian continent +
American Indians + can only be seen on northern
hemisphere, older than 10.000 years before
ancestors American Indians crossed the bering
strait.
summer sun orbit in the sky much larger than the
orbit in the winter lower sun in winter
Ecliptic – sun’s yearly path among the stars =
projection earths orbit on the sky
zodiac sign = constellation in which the sun was at
the moment of your birth can not see your zodiac
constellation on your birthday because the sun is in
front of it and produces so much light you can only
see the sun and not the stars further back
Nabta – Egypt
- oldest astronomical megalithic monument
- 6.000-6500 years old
- complex calendar circle
- marks summer solstice and maybe even the orion belt+shoulders
3
, Stonehenge
- marks longest and shortest day of the year
- built in 3 stages
- 3100BC 300BC and 2600-2000BC
- solar observatory
Newgrange – Ireland
- 3300-2900 BC
- chamber at the end of the corridor is lightened
one day pf the year
Goseck
- Germany
- Europe’s oldest observatory
- circular solar observatory
- winter and summer solstice
stars
Circumpolar star – any star closer than your latitude to your visible celestial pole (north
or south, south pole doesn’t have a polar star) will always be above your local horizon,
so it doesn’t set or rise it goes in a circle above your head rotating around the celestial
pole
As the earth moves in its orbit throughout the year, we see the sun move over the sky,
stars located in the part of the sky visible during the day are not visible as the sun is too
bright. Only stars visible on sky after sunset and the ones rising before dawn will be visible in the
given time of year
Sirius
- helical rising of this star announced the annual flooding of the Nile in Egypt. key importance
for retaining the fertility of the soil around the Nile
Palaeolithic lunar calendars
- ishango – 20.000-25.000 yrs old, linear notches in 3 rows
- Blanchard bone – 30.000 yrs old. lunar calendar on bone
Moon
- 29 days
- w-side moon lit in the evening, e-side moon lit in morning
- changes shape and size during a month
o caused by elliptical orbit around the earth
- moon orbit’s plane oscillates
- we can see more than ½ (~55%) of the moons surface due to its
elliptical orbit
- the moon orbit also rotates itself with respect to the ecliptic plane
resulting in a systematic circular shift of the nodes
- time of the moon to rotate is the same as the time of the moon to go
around the earth that’s why we only see one side of the moon
- The regularity in the occurrence of an Eclipse is therefore the result of 3
periods: - synodic month: motion of moon around earth, wrt. Sun) - draconic month: time
between passes of the moon through nodes of its orbit - anomalistic month shift of moon
orbit, ie. of its perigee and apogee
4
