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Threshold
a moment when something critical happens or appears in the universe
Goldilocks Conditions
conditions that are just right for making complex things, including the right environments, ingredients, and energy.
What was the first threshold in the creation of Earth?
the Big Bang
What were the Goldilocks Conditions for the first threshold in the creation of Earth?
There’s little evidence, and we can only speculate
What did the Big Bang provide?
the raw materials in everything around us
Energy and matter were the same until…
Energy separated into gravity and electromagnetism, and matter separated into quarks and electrons
What was threshold 2 in the creation of Earth?
The stars light up.
How long after the Big Bang was the second threshold?
380,000 years
What did the universe look like up until threshold two?
it was called a plasma and was made up of charged particles with no structure. The temperature was low enough for the fusion of neutrons and protons to occur.
What were the ingredients for threshold 2?
hydrogen, helium, gravity, and heat
Goldilocks Conditions for threshold 2?
10 million degrees celsius and tiny variations in the density of matter throughout the universe
What happened during threshold two?
dense regions were brought together by gravity, and it got so hot that protons and neutrons separated again. Protons fused, turning into energy, which lit up the stars.
What did the illumination of stars reveal?
clusters and super clusters of galaxies
What was threshold 3?
New chemical elements formed
What allowed for the creation of new elements?
The aging and deaths of stars (supernova)
what were the ingredients for threshold 3?
very high temperatures and aging/dying stars
Goldilocks conditions for threshold 3?
stars running out of hydrogen and giant stars collapsing
What new complexity was born with threshold 3?
Chemistry
What was threshold 4?
the creation of planets
What is accretion?
the process in which matter particles clump together to form larger objects, until planets are produced
What happened during threshold 4?
Clouds of matter spun around newly formed stars, and atoms/molecules clumped together (accretion)
What makes rocky planets rocky?
Solar winds blow away the outer gaseous layers, leaving only heavier elements.
How old is our solar system?
More than 4.5 billion years
Ingredients for threshold 4?
new stars and chemically rich matter
Are astronomical bodies (planets) more or less chemically rich than stars?
Astronomical bodies are MORE chemically rich
Goldilocks conditions for threshold 4?
gravity, accretion, and random collisions
When and how did the Sun form?
5 billion years ago a nebula (made mostly of H and He) floated in on one of the spiral arms of the Milky Way Galaxy. It began to contract and collapsed in on itself, and then fusion started. Energy and heat was created, and the Sun was born.
Planetismal
A body that could or did come together with many others under gravitation to form a planet.
Protoplanets
a large body of matter in orbit around the sun or a star and thought to be developing into a planet.
What are the requirements for a body to be a planet?
must orbit the Sun, must be massive enough to have its own gravity make it spherical, and has to have cleaned its area of smaller objects
How do we know how old the solar system is?
by dating the rocks from the asteroid belt, which formed at the birth of the solar system
What was the asteroid belt formed from?
leftover metallic materials from the formation of the solar system
Earth has a core made of ___, while Mercury and mars are _________ to their cores because _______.
Magma, rigid, they are smaller
Why is Earth associated with Goldilocks?
because it has the perfect conditions to support life
How did the Moon form?
A small contending planet crashed into the Earth about 4.45 billion years ago. Some of the material was absorbed into Earth but some was ricocheted into space. That material settled into an orbit and condensed into the Moon.
What does the Moon do for Earth?
the Moon’s gravity creates the oceans’ tides, reduces Earth’s wobble, stabilizes climate, and slows Earth’s spin (makes days longer).
How was Earth affected when the Moon collided with it?
Earth was tilted on its axis, creating seasonal variations in temperature and sunlight (seasons).
Radioactive elements
Elements with nuclei that are unstable and will spontaneously decay (breakdown), releasing particles and radiation.
Radioactive decay converts the __ element into a smaller, more stable atom, the ____ element.
Parent, daughter
Each radioactive element has a decay rate that is _____
constant
Half life
the amount of time it takes for one-half of the radioactive isotope to decay
if a sample contains 100g of the radioactive element Co-60, how much will be left after one, two, and three half lives?
50g after 1, 25g after 2, 12.5g after 3
The original radioactive isotope has a mass of 10g. After 2 days, 5g is left. What is the half-life of the isotope?
2 days
Relative dating
dating that doesn’t offer specific dates, it simply allows to determine if one artifact, fossil, or rock layer is older than another
Absolute dating
dating that provides more specific origin dates and time and time ranges, such as an age range in years
Scientists use radioactive decay to measure…
time
When an unstable radioactive atom decays, it decays into:
a more stable atom (called the daughter product)
Aluminum-26 has a half-life of 740,000 years. In a rock sample, there is an equal number of Aluminum-26 parent atoms and magneiusm-26 daughter atoms. How old is this rock?
740,000 years
Why can't carbon-14 dating be used on dinosaur remains like the dinosaur skull?
Carbon dating is only accurate to 50,000 years ago and dinosaurs are older than that
As the depth an object is located underground increases, the age of that object __________.
Increases
As the amount of parent isotope decreases in an object, the age of that object _______________.
Increases
Which radioactive element is better for dating materials that inform the age of the solar system and planet?
uranium-235
Note
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