At Home in the Universe FINAL

Why does the length of the day vary throughout the year?

-due to the tilt of Earth's axis of rotation to that of its path around the sun

-Earth's axis is not straight (90º), so the axis is inclined.

What is the month based on?

-moons rotation around earth

What is the year based on?

-duration of Earth's orbit around the sun

What is precession? And how long is it?

Earth's rotational axis

-points at different stars after cycle

-the longer term astronomical cycle ~26,000 years

What is obliquity? And how long is it?

_earths axis tilt

~41,000 years

How do eclipses prove that the Sun and the Moon are different sizes?

-solar eclipse the sun's rays are only partially blocked by the moon

-can only be seen on small areas on earth

Plato

Mathematic reasoning

point of origin and creation

earth static

doesn't care about past

expanding universe

Aristotle

Eternal universe

why and how

no time before time

no origin

no math

no creator

time is unchanging

earth static

steady state

Stoics

cyclic universe

fatal necessity

cosmological gods

cycles

cosmic rhythm

great year

recollapsing universe

Epicureans

Linear universe, progress

No gods

don't belive in evolution but in natural selection

specific time of creation

Direct evidence

Evidence that establishes the existence of a fact that is in question without relying on inference.

Indirect evidence

could lead to a conclusion

Antikythera Mechanism

Greek mechanical calculating devise

Physical evidence of knowledge at that time

Greek computer or calculator

calculated astronomical cycles

How did we date the pyramids

....

Induction

Generalizations based on observations

universal statements

Deduction

applying observations from induction and applying to laws and theories

Eratosthenes

calculated the circumference of the earth

Determined Earth was round

Determined Sun rays are roughly parallel approaching Earth but strike at different angles because of Earth's curvature

Why did Eratosthenes hypothesized that the Earth was a sphere?

Earth's shadow appears round during a lunar eclipse

Aristarchus

Calculated distance of Earth, Moon, Sun

115:1 ratio

Calculated angles

How big is the Earth's diameter relative to the Moon's?

The Earth is about 3.5 times bigger than the Moon's

How did Eratosthenes calculate the circumference of the Earth?

Using geometry and the shadows cast by the sun and top of column at Alexandria is the same as angle at center of earth subtended by Alexandria and Syene.

How did Eratosthenes and Aristarchus findings effect people

People didn't accept it for over a 1000 years

earth was bigger than they thought

originally Based on their views on the geocentric Solar System

Parallax Method

Uses trigonometry to calculate the distance between Earth and relatively close stars

time of year affects what star earth is facing

Cephid variable

Used to calculate distance between Earth and relatively distant stars

Relationship between periodicity of a stars' brightness and its luminosity

Varies in brightness

Compares absolute brightness with apparent brightness

Difference between absolute and apparent brightness

Absolute:brightness we could calculate energy star putting out using math

Apparent:brightness we could determine based on what we see, dimmed

All models of universe

Recollapsing

Critical-expands but stays stagnet

Coasting-continues to expand

Accelerating-rate of expansion increases through time

What is the current "accepted" model of the universe?

Accelerating, started with Big Bang continues o expand

Blueshift

Doppler shift of an object coming towards us. (Shorter wavelengths of visible light are bluer)

Redshift

shift of light to a longer wavelength as it moves away

Doppler effect

Increase/decrease of waves as the source and observer move toward/away from one another

Appeared to be stretched out as if they were moving away from us(greater red-shift)

Frequency change depending on movement

Cosmic Microwave Background

Electromagnetic radiation left over from Big Bang

Strongest redshift

Age and formation of solar system?

4.5 billion years

How do we know how the solar system formed?

Super novas

What is the asteroid belt?

Small planetary bodies that circle the sun in a belt between the orbits of Mars and Jupiter

separates gas planets

How do we use craters to date planets?

Many craters indicate the planet is old and has gone through many asteroid impacts and the surface isn't that active

Can we change an element's half-life?

The half-life never changes

Why is Venus' surface so much hotter than Earth's?

It has more carbon dioxide in the atmosphere which causes a runaway greenhouse effect

Endogenous energy

How has heat energy been transferred from the interior of the planet, where radioisotopic material is concentrated, to the outside, causes mountains

Exogenous energy

How much energy is received by the planet's surface from external sources

the sun

cause sand dunes and movement of water (moon)

What makes a planet habitable?

Perfect distance from Sun

Perfect Mass for its atmosphere

Good geological activity

Differences and similarities between Earth, Venus, and Mars

Earth-more geological activity than other planets

Mars-Extremely cold/extremely low pressure/smaller than other two planets/More impact craters than Venus

Venus-Same size/density as Earth/Same amount of carbon dioxide as Mars/Larger mass in atmosphere than Earth/Extremely hot

Principle of Uniformitarianism

The present is the key to the past

Principle of Original Horizontality

Sedimentary and volcanic rocks are deposited in horizontal layers

Principle of Lateral Continuity

Sediment forms into continuous lateral layers

Layering effect continues until the sediment thins to nothing or terminates at the edge of another layer

Principle of Superposition

Sediment is deposited in upward stacking layers with the oldest layer at the bottom and the youngest layer on the top

Principle of Cross-Cutting Relationships

If a rock layer or fault cuts across another rock layer or fault, then the feature that is cut across must be older

Principle of Inclusion

If a rock contains fragments of another rock, then the included fragments are older than the rock that encloses them

2 main ways this occurs:

Pieces of preexisiting rocks get included as sedimentary particles in sedimentary rocks

Pieces of rock get bombarded with hot magma. These rocks do not melt completely, but instead when the magma cools the preserved bits of rock are visible

Uncomformity

A contact between two or more rock units where there is a gap in time

What biolological data do we use to understand the first life forms?

carbon isotopes

What geological data do we use to understand the first life forms?

rock layers, metorrite impacts

What are the Big 5?

End-Ordovician, Late Devonian, End-Permian, End Triassic, End-Cretaceous.

What was the biggest of the Big 5?

End Permian

End Ordovician

3rd largest overall, 2nd largest marine extinction

Late Devonian

359 mya, 75% of all species wiped out

End-Permian Extinction

Largest mass extinction which resulted in the disappearance of 90% of all species

End Triassic Extinction

~199 million years ago to 214 million years ago. massive amounts of lava erupted from the mid atlantic rift. led to the break up of pangea. deadly global warming.

End-Cretaceous extinction

Mass extinction, 65 MYO, of 60-80% of the multicellular species alive, including the dinosaurs (except birds). Hypothesized to have resulted from the impact of an asteriod hitting the earth.

carbon isotopes

Carbon 12 and carbon 13

less neutrons

Chemical indicator of life

used as evidence

solar eclipse

an eclipse in which the sun is obscured by the moon

small shadow on earths surface due to moon being small

lunar eclipse

an eclipse in which the moon appears darkened as it passes into the earth's shadow

how do we measure distances from far away

close, radar

nearby, parallax

milkyway, main sequence fitting

nearby galaxies, cepheids

distant galaxies, distant standards and hubbles law

objects far from earth

dim as seen from earth, old and large

further away more time it took for light to travel

age and distance

directly related, light we see from objects that are further away are older, light emitted long ago

why is the core hot

radioisotopic decay of elements generates heat, this heat has to transferred

How does earth cool itself down

melting old cold material

Why is gravity important

more atmosphere and hold gases to planet

Erosion

The process by which wind, water, ice, or gravity transports soil and sediment from one location to another

material from mountain tops transfered to lower elevation

Why doesn't earth have craters

our atmosphere , resurfacing planet, active surface due to endogenous energy

igneous rock

rock that forms when melted rock cools and hardens

endogenous energy

sedimentary rock

a rock that forms from compressed layers of sediment

movement of material on surface

exogenous

metamorphic rock

rock altered by pressure and heat in the crust

rock comes to surface

endogenous

exoplanets

A planet that orbits another star find them with radial velocity, light spectrum as it orbits star

habitable zone

the region around a star in which planets could potentially have surface temperatures at which liquid water could exist

orgainic molecules

occur naturally from life forms

dead matter

not only on earth

Isotopes

Atoms of the same element that have different numbers of neutrons

divergent plate boundary

Boundary between tectonic plates in which the two plates move away from each other, and new crust is created between them, magma comes up

Geo-centric model

Earth is the center of the Universe

Heliocentric

Based on the belief that the sun is the center of the universe

Why is fossil record sparse insome places and abundant inothers?

how did extinctions kill so many organisms

Volcanism -> raised CO2

methane

High CO2 and methane=greenhouse

Collapse of ecosystems on land= increase in acidic runoff

Warm temps lower O2 saturation in

ocean=anoxia in oceans and acidification

Why are there regular 'cycle'-type things?