Test 2 Flashcards
What is nucleosynthesis?
process that creates new atomic nuclei from pre-existing nucleons, primarily protons and neutrons
Tell me about the Big Bang Nucleosynthesis?
-90% of the universe is composed of H and He
-Almost all H, He were created in the first 3 min after Big Bang
-universe cooled enough for H atoms to form, then fuse to form HE
-H + H =H2
-H2 + H2 = He
-Process ended after ~ 20 minutes (cooled and density decreased as early universe expanded
-Earliest nebulae composed of 3/4 H and 1/4 He (no stars yet)
Review: what’s a Nebulae?
patchy cloud of gases and dust
what was the periodic table right after the Big Bang?
H, He, Li ,Be
Stellar Nucleosynthesis, tell me about it?
-started; 500 may after B.B
-larger atoms made from smaller under high heat and pressure
-nuclear fusion and fission
during stellar nucleosynthesis, atoms gets released from a star, explain it…
-it happens during its lifetime via the stella wind
-as it dies, samll and medium starts become red giants, large stars become supernova explosions
-all elements starting with C produced this way
-stars are element factories
Triple-alpha process is an example of what?
2 Helium atoms forming Be,
Be + He = C
What is cosmochemistry?
study of chemical composition of matter in the universe and the processes that led to those compositions.
Natural samples: meteorties, asteroids, comets, returned samples
Remote spectroscopy: planets, stars, nebulae
Numerical modeling
what is a meteorite?
An extraterrestrial rock that survives an impact on the Earth
what’s the development of cosmochemistry in 20th century? (3)
1- invention of isotope mass spectrometer measure isotope ratios
2-apollo program and state-of-the art analytical facilities to anylyse lunar samples
3-allende carbonaceous chondrite meteorite
what is the Hourglass Nebula?
a young planetary nebula
where do meteorites come from?
material that is as old as S.S and provides scientists with a record from the early solar nebula
what are carbonaceous chondrites?
stony meteorites that have retained many of their chemical properties since their formation 4.56 billion yeas ago
why are carbonaceous chondrites important?
major focus of cosmochemical investigations
what’s a prime example of carbonaceous chondrite?
Allende meteorite
what do the most primitive meteorites contain?
small amount of presolar grains (older than S.S) coming from supernovae
what are the most abundant elements in the earth’s crust?
Si + O
what are 5 silicate mineral examples?
-feldspar
-quartz
-olivine
-Mica
-Pyroxene
who completed the first crewed trip behind the far side of the Moon?
Apollo 8, dec 1968
What were some early ideas about the Moon?
Plutarch:
-Moon had deep recesses; shadows of rivers or deep chasms
-entertained the possibility that the Moon was inhabited
Was the Moon highly reflective which if so, meant what?
according to William Gilbert
yes and it meant covered in oceans
Earlier science ideas:
what was the 3 hypothesis?
1- Fission; early Earth spun so fast it spun off the moon when it was still molten (Darwin)
2-Capture; Moon formed somewhere else in solar system where there was little iron, then captured into orbit around earth by gravity
3-Coaccretion; Moon is a sister world that formed in orbit around Earth at the same time
What was pre-Apollo knowledge?
-Moon density = 3.3 g/cm^3
-Close to Earth’s mantle
-Moon is fluffy, loose dusty
what does Maria mean towards the Moon?
seas in latin.
Smooth, low-lying plains
-few craters (younger)