ast 301 search for extra terrestrial life

astrobiology

the study of life in the universe

exoplanets

planets that orbit a star other than our sun

hallmarsk of science

explain and test natural phenomena

scientific theory

summarizes a hypothesis supported by repeated testing

mass of the sun

1.989 x 10^30 kg

age of the solar system

4.5 x 10^9 years (4.5 billion years)

how much of the solar system's mass lies with the sun

99.8%

orbital plane

geometric space where a celestial body orbits something else

gas giants' construct

molecular hydrogen and metallic hydrogen

ice giants' construct

hydrogen, helium, methane gas, mantle (water, ammonia, methane ice), core (rock, ice)

habitable zone

the range of orbital distances where water can exist on a planet's surface

planetesimal accretion

the process where solids get stuck together and gain enough gravity to pull in more objects and debris

earth formed by:

planetesimal accretion over 50 million years

earth differentiation

the process where iron was pulled towards earths core and lighter material flows upwards to the surface, forming the planets layers

the earth's layers

solid crust, solid mantle, liquid outer core, solid inner core

cause of earth's tectonic movements

convective motion of the outer core and the release of the planet's inner heat

igneous rock

cooled magma or molten rock

methamorphic rock

rock transformed by either heat or pressure

sedimentery rock

rock built up over time from pieces of other rocks

radiometric dating

the process where you measure the age of a rock by checking the decay of radioactive material and half lives

order of earths timeline

hadean era, achean era, proterozoic era, phanerozoic era

precambian age covers:

hadean, archaen, and protozoric eras

properties of hadean era

earth's formation, moon's formation, meteor bombardment, oldest mineral and grains, ocean's formation, 4.6+ billion years ago

properties of the archaen era

evolution of life, earliest fossils date back to here, 2.5-4 billion years ago

properties of the proterozoic era

first cells with a nucleus and first hard shelled animals, .5 - 2.5 billion years ago

properties of the phanerozoic era

dinosaurs emerge then die then humans are born, .5 billion years ago

who theorized continental drift

alfred wegener

proof of continental drift

fossils for similar animals existed on multiple continents, and some continents appeared to have once fit together

speed of continental drift

2-10cm per year

what causes earth's magnetic field

charged particles in the outer core moving with the conductive metal

what causes earths magnetic poles

rapid rotation of the earth

how is earths magnetic field protecting the planet

charged solar particles are pushed away from the earth or pulled toward the poles by the charged particles of our own atmosphere

origin of the atmosphere

asteroids brought in ice, heated to form water vapor, water vapor grouped together and fell back to earth as condensation forming the ocean, swept carbon dioxide into rocks leaving nitrogen in the atmosphere

gasses that make up earths atmosphere

nitrogen (78%), oxygen (21%)

what is the greenhouse effect

solar particles are sent to the earth and most are blocked by the CO2, half is absorbed by the earths surface and transformed into heat and infrared energy, some of it is reabsorbed and the restpasses back into space

what does the greenhouse effect do for the earth

the greenhouse effect keeps earth from being completely frozen

what is the carbon dioxide cycle

rainfall erodes rocks on land, rivers carry them out to sea, minerals react with dissolved co2 and form carbonate rocks, carbonate subducts and melt releasing co2 back into the atmosphere

what does the carbon dioxide cycle do for earth

it helps regulate the earth and keep it from being too hot or too cold

what happened to end the ice age

higher reflectivity of the ice caused further cooling of earths surface (the infrared was not absorbed), planet freezes and co2 cycle stops and causes a buildup of co2 in the atmosphere, strong greenhouse gasses reheat the earth

what makes something alive

1) growth and development
2) biological organization/order
3) ability to reproduce
4) ability to use energy
5) can respond to enviornment
6) can adapt and evolve

major parts of evolution

genetic mutations - random genetic changes
natural selection - having traits that make one better suited for the enviornment

why is life considered to be carbon based

the atomic structure of carbon allows for long chains of molecules that other elements can attach onto and provide for many chemical properties

why is life considered to be dependent on water

water makes up 70% of all living things and is the medium where biochemical reactions take place

most common elements in the universe, and why

hydrogen (75%), heluim (24%), oxygen and carbon
stars initially only had hydrogen and helium to use, and produced heavier elements in their deaths (rarely heavier than massive star supernovae)

monemer

small molecule consisting of many elements for life, like amino acids

polymer

macromolecule made up of repeating structural units

RNA

macromolecule made of strands of nucleotides containing genetic information

DNA

double helix macromolecule made of strands of nucleotides containing genetic information

what do we think all life shares a common ancestor

all known life uses DNA in their cells and ATP to create energy,

who discovered DNA

Rosalind Franklin

protein

biochemical compound that facilitates biological function

enzyme

proteins that increase the rates of chemical reactions

heterotroph

organism that consumers other substances for carbon and metabolizes energy from it

autotroph

organism that obtains carbon from the enviornment and metabolizes energy from it

gene

basic unit of heredity in a living organism and maintqain cells to pass traits to offspring

Millerr-Urey Expeiment

experiment suggesting uv radiation caused molecules in the primordial enviornemnts of earth to form simble organic compounds